Wyoming State Water Plan, Wyoming Water Development Office
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Powder/Tongue River Basin Water Plan
Final Report

III      Available Surface Water and Ground Water Determination

This chapter presents estimates of the availability of surface water to meet future water uses and also characterizes the potential for ground water development.

As with all chapters in this final plan report, explicit lists of references are not provided. Instead, all references to reports, maps, and personal communications are provided in the various Technical Memoranda prepared during the planning process. The reader is referred to the following technical memoranda for a more detailed description of each topic as well as the list of references:

A.     Surface Water
The determination of available surface water is broken down into seven components discussed in the following sections:
  1. Compilation of Historic Streamflow Records
  2. Study Period Selection
  3. Data Extension
  4. Estimating Natural Flow at Ungaged Model Nodes
  5. Determining Streamflows during Wet, Normal, and Dry years
  6. Spreadsheet Model Development and Calibration
  7. Determination of Available Surface Water
It should be noted that the results described herein pertain to physical availability over and above existing uses, which is to be distinguished from legal or permitted availability. Physical availability is the important first step in assessing the viability of any future project. Lack of physical availability of water for a project is an obvious fatal flaw for any water development.

Historic Streamflow Records

Available records of streamflow in the Powder/Tongue River Basin planning area have been compiled for this study.

The location of the various streamflow gaging stations are plotted in relation to the significant storage reservoirs and the irrigated lands mapped for the Basin Plan (Figures III-1 through III-4). The streamflow gages that are relatively free from the influence of depletions or storage regulations are characterized as natural flow stations. Where reasonably possible, those gages that are impacted by upstream irrigation depletions were adjusted to remove these effects. The list of streamflow gages inventoried for this study is provided in Table III-1.


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Records from an additional 40 to 50 streamflow gaging stations are available beginning in the 1970s and 1980s in comparison to those gages with earlier records.

Study Period

It is important in any water availability evaluation to select a study period that is long enough to include a variety of hydrologic conditions including an extended period of dry years as well as wet years and normal years. At the same time, it is also important not to select a study period so long that many streamflows must be synthesized to fill-in missing data.

The USGS has maintained a streamflow station on the Tongue River near Dayton (#06298000) since 1919 and continuous records are available from 1941 to present (Table III-1). This station is impacted by diversions to the Highline Ditch just upstream of the gage. Natural flow at this station is therefore determined by adding these recorded diversions to the recorded streamflow. The 59- year period of continuous record for this station (1941 through 1999) is selected as the best single representation of long term natural hydrologic conditions in the basin. Figure III-5 is a Cumulative Surplus/Deficit plot for the Tongue River near Dayton and represents a running total of the annual deviations from the long-term mean annual streamflow. Downward sloping lines (left to right) represent periods of time during which annual streamflow is less than the long-term mean. Conversely, upward sloping lines represent years which are wetter than average. As shown on Figure III-5, the periods from 1941 through 1947 and from 1962 through 1978 can be generally characterized as wet periods, whereas the periods from 1948 through 1961 and from 1979 through 1989 can be generally characterized as dry periods. The period from 1990 through 1999 can generally be characterized as near average. Exceptions to each of these generalities exist within each period. By way of example, 1966 is a dry year within a generally wet period of years and 1984 is a wet year within a generally dry period. Based on an evaluation of the long-term hydrologic conditions on the Tongue River, together with the an understanding of the availability of historic streamflow records, the 30-year period 1970 through 1999 was selected as a candidate study period. Selection of this potential study period is also influenced by the fact that ditch diversion records are available predominantly for the period after 1970. Both streamflow records and ditch diversions records are needed to develop water availability models that accurately simulate existing water use in the basin. As shown on Figure III-5, the average annual flow of the Tongue River near Dayton, for the period 1970 . 1999, is essentially equal to the long-term (1941 . 1999) average annual flow (133,175 AF vs. 133,210 AF).

The representativeness of the 1970 to 1999 study period was further evaluated by reviewing long- term natural flow gages that more completely represent the entire Powder/Tongue River Basin, including the Little Bighorn River, the Tongue River, and the Powder River. Three gages with relatively long periods of record are selected for this purpose: 1) Little Bighorn River at State Line (#06289000); 2) Tongue River near Dayton (#06298000); and North Fork Powder River near Hazelton (#06311000). The average annual flow for the period 1970 to 1999 is relatively close to

Table III-1
Streamflow Stations in the Powder/Tongue River Basins
Basin Station
Number
Station Name Natural Flow Period of Record in Water Years
**
Note
Little Bighorn
06288600 Little Bighorn River Below Dayton Gulch Near Burgess Junction, WY YES 1983-1987
06288700 Dry Fork Little Bighorn Below Lick Creek Near Burgess Junction, WY YES 1983-1987, 1993-1995
06288960 Little Bighorn River Near Parkman, WY YES 1970-1972
06288975 Elkhorn Creek Above Fuller Ranch Ditch Near Parkman, WY YES 1983-1987 No winter records in 1985
06288990 West Fork Little Bighorn River Near Parkman, WY YES 1970-72, 1983-1987 No winter records in 1987
06289000 Little Bighorn River at State Line Near Wyola, MT YES 1939-current
06289100Red Canyon Creek Near Parkman, WY YES 1982-1990 No winter records in 1985, 1987
06289500 Little Bighorn River Near Wyola, MT NO 1912-1924 No winter records; Abt. 7 mi. into MT
06289600 West Pass Creek Near Parkman, WY NO 1983-current No winter records 1985-1987
06289800 East Pass Creek Near Parkman, WY YES 1975-1976
06289820 East Pass Creek Near Dayton, WY NO 1983-current
06289870 Twin Creek Near Parkman, WY NO 1983-1990 No winter records 1985-1987
06290000 Pass Creek Near Wyola, MT NO 1939-1975 Winter records incomplete before 1939; Abt. 4 mi. into MT
06290500 Little Bighorn River Below Pass Creek Near Wyola, MT NO 1939-1975 Abt. 13 mi. into MT
06291200 Lodge Grass Creek at State Line Near Wyola, MT YES 1982-1989 No winter records 1986
Tongue 06296500 North Fork Tongue River Near Dayton, WY YES 1945-1958 No winter records before 1950
06297000 South Fork Tongue River Near Dayton, WY YES 1945-1972
06297480 Tongue River at Tongue Canyon Campground Near Dayton, WY YES 1975-1979
06298000 Tongue River Near Dayton, WY YES 1919-1929, 1941-current Adjusted using Highline Ditch Near Dayton, WY (06297500) as published
06298480 Little Tongue River at Steamboat Point Near Dayton, WY YES 1975-1976
06298490 Little Tongue River Above South Fork Little Tongue River Near Dayton, WY YES 1975-1976
06298500 Little Tongue River Near Dayton, WY YES 1951-1974
06299000 Tongue River at Dayton, WY NO 1903-1904 Seasonal (May 1903 to Oct. 1904)
06299480 Wolf Creek Below Alden Creek Near Wolf, WY YES 1975-1976
06299490 Wolf Creek Above Red Canyon Creek at Wolf, WY YES 1975-1976
06299500 Wolf Creek at Wolf, WY YES 1945-current No winter records after 1971
06300000 Tongue River at Carneyville, WY NO 1911-1917 Seasonal only
06300500 East Fork Big Goose Creek Near Big Horn, WY YES 1954-current No winter records after 1973
06300900 Cross Creek Above Big Horn Reservoir Near Big Horn, WY NO 1961-1971
06301000 Cross Creek Near Big Horn, WY NO 1954-1960
06301480 Coney Creek Above Twin Lakes Near Big Horn, WY YES 1991-current No winter records 1993, 1996, 1998, 1999
06301485 Lost Lake Creek Near Big Horn, WY YES 1991-1993
06301490 Snail Creek Near Big Horn, WY YES 1991-1993
06301495 Coney Creek Below Twin Lakes Near Big Horn, WY NO 1991-1994, 1996-current No winter records some years
06301500 West Fork Big Goose Creek Near Big Horn, WY NO 1954-current No winter records after 1971
06302000 Big Goose Creek Near Sheridan, WY NO 1929-current No winter records after 1971; Adjusted for diversions using PK Ditch &
Sheridan City Intake Ditch
06302200 Big Goose Creek Above Park Creek Near Sheridan, WY NO 1999-current Jul. - Sep. 1999
06302500 Goose Creek at Sheridan, WY NO 1909-1916 No winter records
06303000 Willow Creek Near Big Horn, WY NO 1954-1955
06303500 Little Goose Creek in Canyon Near Big Horn, WY NO 1941-current No winter records after 1971
06303700 Little Goose Creek Above Davis Creek Near Big Horn, WY NO 1999-current Jul. - Sep. 1999
06304000 Little Goose Creek Near Big Horn, WY NO 1919-1922 No winter records 1919
06304500 Little Goose Creek at Sheridan, WY NO 1896-1897, 1911-1913 No winter records
06305000 Goose Creek Below Little Goose Creek at Sheridan, WY NO 1896-1897 No winter records
06305500 Goose Creek Below Sheridan, WY NO 1942-1984
06305700 Goose Creek Near Acme, WY NO 1984-current
06306000 Tongue River Near Acme, WY NO 1939-1957
06306100 Squirrel Creek Near Decker, MT NO 1975-1986 Abt. 3.5 mi. into MT
06306250 Prairie Dog Creek Near Acme, WY NO WRDS: 1965-1970; USGS: 1971-
1980; SEO: 1981-1999
State data seasonal only
06306300 Tongue River at State Line Near Decker, MT NO 1960-current
Powder 06309200 Middle Fork Powder River Near Barnum, WY YES 1961-current
06309260 Buffalo Creek Above North Fork Buffalo Creek Near Arminto, WY YES 1975-1979
06309270 North Fork Buffalo Creek Near Arminto, WY YES 1975-1979
06309280 Buffalo Creek Below North Fork Buffalo Creek Near Arminto, WY YES 1975-1979
06309450 Beaver Creek Below Bayer Creek Near Barnum, WY YES 1975-1989
06309460 Beaver Creek Above White Panther Ditch Near Barnum, WY YES 1975-1989
06309500 Middle Fork Powder River Above Kaycee, WY NO 1949-1970, 1984-1992
06310000 Red Fork Powder River Near Barnum, WY NO 1929-1932, 1950-1954
06310500 Middle Fork Powder River at Kaycee, WY NO 1911-1913, 1929-1932
06311000 North Fork Powder River Near Hazelton, WY YES 1946-current
06311060 North Fork Powder River Below Bull Creek Near Hazelton, WY YES 1975-1992
06311400 North Fork Powder River Below Pass Creek Near Mayoworth, WY NO 1974-current
06311500 North Fork Powder River Near Mayoworth, WY NO 1941-1973
06312000 North Fork Powder River Near Kaycee, WY NO 1911-1912, 1929-1932
06312500 Powder River Near Kaycee, WY NO 1934-1935, 1938-1971, 1979-1980
06313000 South Fork Powder River Near Kaycee, WY NO 1911-1912, 1938-1940, 1950-
1969, 1979-1980, 1983-1984

06313180 Dugout Creek Tributary Near Midwest, WY YES 1975-1983
06313400 Salt Creek Near Sussex, WY NO 1976-1981, 1983-1993
06313500 Powder River at Sussex, WY NO 1938-1940, 1950-1957, 1978-1999
06313700 Dead Horse Creek Near Buffalo, WY NO 1972-1990
06313950 North Fork Crazy Woman Creek Below Pole Creek Near Buffalo, WY YES 1974-1984
06314000 North Fork Crazy Woman Creek Near Buffalo, WY YES 1942-1949, 1974-1984
06314500 North Fork Crazy Woman Creek Below Spring Draw Near Buffalo, WY YES 1949-1972
06315000 North Fork Crazy Woman Near Greub, WY NO 1950-1968
06315480 Poison Creek Below Tetley Spring Near Mayoworth, WY YES 1975-1976
06315490 Poison Creek Near Mayoworth, WY YES 1975-1976
06315500 Middle Fork Crazy Woman Creek Near Greub, WY YES 1942-1972 No winter records 1972
06316000 Crazy Woman Creek Near Buffalo, WY NO 1929-1932 No winter records some years
SEO Gage Crazy Woman Creek at Trabing Bridge Near Buffalo, WY NO SEO: 1982-current Seasonal data only
06316400 Crazy Woman Creek at Upper Station Near Arvada, WY NO 1963-1970, 1978-1981
06316500 Crazy Woman Creek Near Arvada, WY NO 1940-1944, 1950-1964
06317000 Powder River at Arvada, WY NO 1919-current No winter records 1919-1930, 1934
06317100 Powder River Near Arvada, WY NO 1915-1919 No winter records
06317300 Sourdough Creek Near Buffalo, WY YES 1985-1990
06317340 Little Sourdough Creek Near Buffalo, WY YES 1985-1988
06317500 North Fork Clear Creek Near Buffalo, WY NO 1950-1968
06318500 Clear Creek Near Buffalo, WY NO 1894, 1896, 1897-1900,
1917-1928, 1938-1992
Records after Oct. 1987 not equivalent due to diversion by City of Buffalo; Adjusted for diversions using 100 acres of irrigated lands upstream and 6 cfs diversion by Buffalo
SEO Gage Clear Creek in Buffalo City Park Buffalo, WY NO WRDS: 1971-1978;
SEO: 1987-1999
Seasonal data only
06319000 Clear Creek at Buffalo, WY NO 1903-1905, 1911-1912 No winter records
06319470 South Rock Creek at Forest Boundary Near Buffalo, WY YES 1975-1976
06319480 South Rock Creek Above Red Canyon Near Buffalo, WY YES 1975-1976
06319500 South Fork Rock Creek Near Buffalo, WY NO 1941-1943, 1950-1954 No winter records 1941-1943
06320000 Rock Creek Near Buffalo, WY NO 1941-current No winter records after 1971; Adjusted for irrigation using Mowry Basin Ditch
SEO Gage Rock Creek at Mouth Near Buffalo, WY NO WRDS: 1971-1975, 1977-1978; SEO:
1980-1981, 1983, 1985-1988, 1990-1999
Seasonal data only
06320200 Clear Creek Below Rock Creek Near Buffalo, WY NO USGS: 1976-1981; SEO:
1982-1985, 1987-1999
State data mostly seasonal
06320400 Clear Creek at Ucross, WY NO 1976-1981
SEO Gage Clear Creek Below Healy Reservoir Near Buffalo, WY NO 1977-1999 State data mostly seasonal
06320500 South Piney Creek at Willow Park Reservoir, WY NO 1945-1957, 1960-current No winter records before 1948 and after 1971
06321000 South Piney Creek Near Story, WY NO 1951-1980 No winter records 1972-1974
06321100 South Piney Creek Below Mead-Coffeen Ditch Near Story, WY NO 1975-1979
06321500 North Piney Creek Near Story, WY YES 1951-1982
06321800 Spring Creek Near Story, WY NO 1975-1979
06323000 Piney Creek at Kearney, WY NO 1902-1906, 1910-1917,
1919-1923, 1941-current
No winter records some years
SEO Gage Little Piney Creek, WY NO SEO: 1981, 1983, 1985-
1986, 1988, 1991-1999
Seasonal data only; from spot measurements
SEO Gage Piney Creek Below Lake DeSmet Tunnel Intake Near Story, WY NO WRDS: 1971-1973, 1977, 1979;
SEO: 1980-1984, 1986-1996
Mostly seasonal data
06323500 Piney Creek at Ucross, WY NO USGS: 1917-1923, 1980-1982;
SEO: 1983-1987, 1989-1998
No winter records 1917-1923; State data seasonal only
SEO Gage Clear Creek at Double Crossing Near Clearmont, WY NO WRDS: 1973-1978; SEO:
1980-1996, 1998-1999
Seasonal data only
SEO Gage Clear Creek Below P&F#3 Ditch Near Clearmont, WY NO WRDS: 1978; SEO: 1980-1999 Seasonal data only
06324000 Clear Creek Near Arvada, WY NO 1915-1919, 1928-1929, 1940-1982 No winter records before 1929
06324500 Powder River at Moorhead, MT NO 1929-1972, 1975-current Abt. 4 mi. into MT
Little Powder 06324890 Little Powder River Below Corral Creek Near Weston, WY NO 1978-1981
06324925 Little Powder River Near Weston, WY NO 1977-1981
06324970 Little Powder River Above Dry Creek Near Weston, WY NO 1973-current
Belle
Fourche
06426500 Belle Fourche River Below Moorcroft, WY NO 1943-1970, 1976-1983,
1986-1987, 1991-current

**Unless otherwise noted, records were obtained from the USGS.

Figure III-5
Cumulative Surplus/Deficit of Annual Historic Flows -
Tongue River Near Dayton, WY (Station 06298000) - 1941 to 1999

the 1947 to 1999 average annual flow for the three stations (1% to 4% wetter). This period also includes a variety of wet, normal, and dry years at all three locations.

In summary, the period 1970 through 1999 contains extended periods of dry years including some of the driest years of record as well as periods of normal and wet hydrologic conditions throughout the planning area. This period also has the greatest abundance of recorded streamflow data and ditch diversion data and therefore requires less data synthesis. A study period of 1970 through 1999 was therefore selected as appropriate for purposes of water availability modeling for the Powder/Tongue River Basin Plan.

A more detailed discussion and supporting documentation for the selection of the study period are provided in the .Surface Water Hydrology. technical memorandum.

Data Extension

The spreadsheet modeling approach used for the Basin Plan relies on both records of natural flow as well as records from stations impacted by upstream diversions or regulation. Natural flow is supplied to the model, where available, at the headwater nodes and non-natural flow records at downstream gaging stations are used to calibrate the model to historic conditions. Monthly streamflows must therefore be estimated for both categories of gaging stations for those months, during the study period, with no recorded streamflow data.

The monthly record extension approach used in this study follows the procedure used by the USGS in recent studies. This mixed-station procedure uses the best base station from among all available base stations to fill in each month of missing data for a given gage. The base station producing the smallest standard error of prediction is used for each particular month. The technique used to estimate missing values was developed by Hirsch and is referred to as MOVE.1 (Maintenance of Variance Extension, Type 1). This technique offers the advantage over ordinary least-squares regression of preserving the variance of the unextended records. This procedure was carried out using a computer program developed by the USGS.

The USGS and SEO streamflow stations are first divided into natural flow stations and non- natural flow stations. The stations are then further divided into hydrologically similar groups with each group having at least one gage with sufficient data to develop relationships based on concurrent streamflow for the entire study period. The monthly flow extension procedure is performed for each of these groupings of monthly streamflow data. There is a certain amount of overlap in hydrologic similarity among the various groupings. Some streamflow stations are therefore included in multiple groups. Records from the long-term natural flow stations are also included with some of the non-natural flow groupings where appropriate to provide adequate data for extending the records through the entire study period.

Regression of hydrologic data resulting in a coefficient of determination (R2) greater than 0.7 is typically considered strong enough for data estimating. This criterion was used in evaluating the results of the regression analyses performed for this study. The coefficient of determination is defined as the proportion of variation in the independent variable that can be explained by variation in the dependent variable. The higher the value of R2, the stronger the relationship between the two variables. A perfect relationship would have an R2 equal to 1.0. In some instances no significant correlation (R2 less than 0.7) could be found using concurrent monthly streamflows between any base station and the short record station. Annual flow regression rather than monthly flow regression was performed in these instances to fill-in the missing streamflow data. In a few cases, no significant correlation (R2 less than 0.7) could be found using the annual flow regression either. These stations were dropped from the study. The monthly streamflows for the years of missing data were estimated by applying the average monthly distribution for the period of recorded streamflow to the estimated total annual flow.

The average monthly and annual streamflows for the 1970 to 1999 study period, for the natural flow streamflow stations and the non-natural flow streamflow stations are summarized in Table III-2 and Table III-3 respectively.

Table III-2
Summary of Average Monthly and Annual Flows (1970 to 1999) - Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06288600 Little Bighorn River Below Dayton Gulch Near Burgess Junction, WY 414 301 268 238 195 215 358 3,600 6,008 1,685 779 463 14,524
06288700 Dry Fork Little Bighorn Below Lick Creek Near Burgess Junction, WY 1,855 1,599 1,498 1,383 1,223 1,326 1,709 6,248 9,433 4,505 2,644 2,029 35,452
06288960 Little Bighorn River Near Parkman, WY 4,011 3,353 3,098 2,864 2,479 2,777 3,771 17,119 27,107 11,347 6,045 4,433 88,404
06288975 Elkhorn Creek Above Fuller Ranch Ditch Near Parkman, WY 114 100 92 86 75 88 141 486 618 202 135 124 2,261
06288990 West Fork Little Bighorn River Near Parkman, WY 939 794 734 672 593 671 896 3,868 5,800 2,421 1,355 1,040 19,783
06289000 Little Bighorn River at State Line Near Wyola, MT 5,420 4,574 4,258 3,958 3,479 3,880 5,154 21,093 32,321 14,270 7,920 5,957 112,266
06289100 Red Canyon Creek Near Parkman, WY 35 32 26 28 23 42 216 561 242 65 32 28 1,330
06289800 East Pass Creek Near Parkman, WY 469 389 366 338 303 328 547 1,899 2,298 1,062 638 508 9,145
06291200 Lodge Grass Creek at State Line Near Wyola, MT 464 352 316 288 242 271 558 3,619 5,268 1,760 780 531 14,449
Tongue
06297000 South Fork Tongue River Near Dayton, WY 1,424 1,033 942 803 652 741 1,839 14,823 22,367 6,444 2,527 1,656 55,251
06297480 Tongue River at Tongue Canyon Campground Near Dayton, WY 5,064 3,935 3,623 3,295 2,824 3,107 6,129 31,109 42,528 15,621 7,855 5,653 130,743
06298000 Tongue River Near Dayton, WY 5,130 3,954 3,642 3,315 2,825 3,117 6,186 31,983 43,180 16,162 7,951 5,730 133,175
06298480 Little Tongue River at Steamboat Point Near Dayton, WY 134 94 83 72 58 69 249 2,165 3,088 726 274 167 7,179
06298490 Little Tongue River Above South Fork Little Tongue River Near Dayton, WY 98 67 58 50 40 46 139 1,641 2,643 591 200 118 5,691
06298500 Little Tongue River Near Dayton, WY 225 158 139 124 105 118 402 3,299 4,503 1,144 427 268 10,912
06299480 Wolf Creek Below Alden Creek Near Wolf, WY 471 341 304 267 219 255 784 6,063 8,521 2,214 855 537 20,831
06299490 Wolf Creek Above Red Canyon Creek at Wolf, WY 536 404 364 329 276 308 784 5,804 8,126 2,169 849 540 20,489
06299500 Wolf Creek at Wolf, WY 539 399 356 317 271 298 854 5,767 7,980 2,237 926 603 20,547
06300500 East Fork Big Goose Creek Near Big Horn, WY 426 284 220 204 154 171 557 5,296 10,978 3,740 1,096 698 23,824
06301480 Coney Creek Above Twin Lakes Near Big Horn, WY 30 18 14 10 8 9 49 1,091 1,781 534 83 48 3,675
Powder 06309200 Middle Fork Powder River Near Barnum, WY 457 416 370 331 295 424 2,125 9,807 5,212 1,061 527 433 21,457
06309260 Buffalo Creek Above North Fork Buffalo Creek Near Arminto, WY 31 28 23 20 17 28 218 1,350 649 101 38 28 2,531
06309270 North Fork Buffalo Creek Near Arminto, WY 86 79 70 62 55 79 370 1,639 915 200 103 84 3,742
06309280 Buffalo Creek Below North Fork Buffalo Creek Near Arminto, WY 0 0 0 0 0 0 34 1,918 950 51 2 1 2,956
06309450 Beaver Creek Below Bayer Creek Near Barnum, WY 185 166 143 126 111 156 519 1,787 1,141 429 247 192 5,202
06309460 Beaver Creek Above White Panther Ditch Near Barnum, WY 612 568 546 518 476 561 997 2,211 1,674 911 695 610 10,379
06311000 North Fork Powder River Near Hazelton, WY 294 220 180 144 120 142 603 3,864 4,037 1,111 471 325 11,511
06313950 North Fork Crazy Woman Creek Below Pole Creek Near Buffalo, WY 629 474 387 307 257 301 1,142 5,582 5,774 1,983 918 645 18,399
06314000 North Fork Crazy Woman Creek Near Buffalo, WY 640 481 395 316 265 307 1,152 5,490 5,637 1,987 924 655 18,249
06314500 North Fork Crazy Woman Creek Below Spring Draw Near Buffalo, WY 558 412 337 264 217 269 1,184 7,726 8,139 2,222 917 624 22,869
06315480 Poison Creek Below Tetley Spring Near Mayoworth, WY 214 175 150 127 112 126 346 1,172 1,155 490 279 218 4,564
06315490 Poison Creek Near Mayoworth, WY 246 202 176 150 132 151 387 1,232 1,220 542 320 251 5,009
06315500 Middle Fork Crazy Woman Creek Near Greub, WY 707 551 470 391 334 411 1,290 5,891 6,016 2,072 1,031 759 19,923
06317300 Sourdough Creek Near Buffalo, WY 70 52 44 34 28 34 107 775 905 265 112 78 2,504
06317340 Little Sourdough Creek Near Buffalo, WY 37 22 7 3 2 5 206 214 139 36 16 25 712
06319470 South Rock Creek at Forest Boundary Near Buffalo, WY 447 341 280 227 187 217 900 5,431 5,744 1,722 714 491 16,701
06319480 South Rock Creek Above Red Canyon Near Buffalo, WY 426 325 264 213 177 205 870 5,367 5,703 1,675 689 471 16,385
06319500 South Fork Rock Creek Near Buffalo, WY 800 626 511 423 354 439 1,817 10,506 10,318 2,733 1,139 842 30,508

Table III-3
Summary of Average Monthly and Annual Flows (1970 to 1999) - Non-Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06289600 West Pass Creek Near Parkman, WY 522 476 441 419 407 497 770 2,023 2,007 810 488 495 9,355
06289820 East Pass Creek Near Dayton, WY 621 575 543 531 519 629 958 2,666 2,800 905 469 530 11,746
06289870 Twin Creek Near Parkman, WY 108 92 119 328 236 741 847 1,656 349 154 115 87 4,833
Tongue
06302000 Big Goose Creek Near Sheridan, WY 2,307 1,727 1,576 1,427 1,199 1,336 2,247 13,175 27,034 8,560 4,642 3,625 68,855
06303500 Little Goose Creek in Canyon Near Big Horn, WY 1,855 1,369 1,274 1,147 968 1,076 2,082 10,835 14,826 6,582 5,236 3,425 50,702
06305500 Goose Creek Below Sheridan, WY 6,692 5,855 5,109 4,570 4,971 6,223 8,284 26,807 40,099 10,115 4,047 5,595 128,367
06305700 Goose Creek Near Acme, WY 6,848 5,984 5,215 4,660 5,076 6,364 8,494 27,713 41,776 10,431 4,120 5,725 132,406
06306250 Prairie Dog Creek Near Acme, WY 2,785 2,192 1,835 1,286 2,567 5,705 2,784 3,701 2,327 1,416 1,730 2,350 30,678
06306300 Tongue River at State Line Near Decker, MT 16,187 13,719 11,317 11,134 13,110 19,427 21,867 73,969 98,409 29,613 11,756 13,340 333,850
Powder
06309500 Middle Fork Powder River Above Kaycee, WY 2,812 2,642 2,490 2,387 2,235 2,693 5,676 14,882 9,586 3,978 2,759 2,581 54,721
06311060 North Fork Powder River Below Bull Creek Near Hazelton, WY 240 169 159 129 119 143 367 3,188 4,121 2,014 1,524 1,028 13,202
06311400 North Fork Powder River Below Pass Creek Near Mayoworth, WY 1,326 1,138 1,139 1,110 994 1,089 1,613 4,891 5,510 2,835 2,410 1,917 25,972
06312500 Powder River Near Kaycee, WY 5,062 6,385 6,481 5,606 6,441 8,416 8,944 27,066 15,875 1,006 888 1,783 93,950
06313000 South Fork Powder River Near Kaycee, WY 172 237 163 190 1,350 7,672 5,987 9,131 2,072 602 1,729 11 29,316
06313400 Salt Creek Near Sussex, WY 2,257 1,820 1,706 1,849 2,577 4,243 3,003 5,395 4,120 3,062 1,940 1,853 33,825
06313500 Powder River at Sussex, WY 10,088 8,646 7,430 7,200 10,592 17,746 17,475 38,478 26,121 9,211 4,476 4,899 162,362
SEO Gage Crazy Woman Creek at Trabing Bridge Near Buffalo, WY 329 223 218 196 150 189 1,697 8,924 13,287 3,211 1,242 978 30,644
06316400 Crazy Woman Creek at Upper Station Near Arvada, WY 1,688 1,356 1,036 885 1,627 2,517 3,386 9,747 8,975 2,196 1,151 769 35,333
06317000 Powder River at Arvada, WY 11,144 9,646 7,235 6,773 11,517 23,619 21,176 52,067 42,800 14,235 6,162 5,400 211,773
06318500 Clear Creek Near Buffalo, WY 2,253 1,583 1,220 909 759 1,009 2,710 12,305 17,834 8,639 3,929 2,749 55,899
SEO Gage Clear Creek in Buffalo City Park Buffalo, WY 1,886 1,397 1,138 947 1,277 1,972 2,407 9,746 14,070 4,659 1,414 1,254 42,167
06320000 Rock Creek Near Buffalo, WY 894 653 587 525 437 490 993 7,108 9,142 3,800 2,729 1,558 28,916
SEO Gage Rock Creek at Mouth Near Buffalo, WY 1,572 1,322 1,026 927 1,272 2,245 1,360 5,460 7,121 1,755 929 918 25,907
06320200 Clear Creek Below Rock Creek Near Buffalo, WY 3,672 3,132 2,571 2,386 2,774 4,084 5,349 17,212 23,059 7,586 3,034 3,074 77,933
SEO Gage Clear Creek Below Healy Reservoir Near Buffalo, WY 2,601 1,730 1,299 1,079 1,454 2,483 3,739 14,926 20,747 7,964 3,380 2,772 64,174
06321000 South Piney Creek Near Story, WY 2,068 1,539 1,514 1,257 961 1,032 1,555 5,964 20,205 12,621 9,042 5,535 63,293
06323000 Piney Creek at Kearney, WY 1,886 2,307 2,059 1,875 1,607 2,038 4,072 15,796 23,765 6,122 2,061 1,265 64,853
SEO Gage Little Piney Creek, WY 784 751 591 583 709 964 945 1,620 1,489 881 602 689 10,608
SEO Gage Piney Creek Below Lake DeSmet Tunnel Intake Near Story, WY 1,524 1,056 741 664 613 864 1,953 10,657 20,258 5,591 2,118 1,431 47,470
06323500 Piney Creek at Ucross, WY 3,450 3,413 2,641 2,362 1,632 2,969 3,928 12,580 20,834 7,887 5,206 3,718 70,620
SEO Gage Clear Creek at Double Crossing Near Clearmont, WY 8,484 7,580 6,042 5,208 5,866 9,456 9,217 27,303 42,211 14,623 7,589 6,807 150,386
SEO Gage Clear Creek Below P&F#3 Ditch Near Clearmont, WY 6,464 5,750 3,619 3,474 5,276 9,697 8,968 24,292 38,482 10,460 4,558 4,444 125,484
06324000 Clear Creek Near Arvada, WY 7,050 6,494 4,356 4,151 5,773 9,919 10,332 25,700 38,174 11,742 5,498 5,462 134,651
06324500 Powder River at Moorhead, MT 18,021 16,072 10,330 10,928 18,963 36,118 29,810 73,536 79,314 27,131 11,758 10,494 342,475
Little Powder 06324890 Little Powder River Below Corral Creek Near Weston, WY 8 16 23 57 182 1,022 138 1,239 103 267 38 0 3,093
06324925 Little Powder River Near Weston, WY 637 128 74 360 2,640 4,275 1,982 3,093 1,600 463 275 161 15,688
06324970 Little Powder River Above Dry Creek Near Weston, WY 823 260 174 580 2,501 4,299 1,602 4,205 1,992 748 404 284 17,873
Belle
Fourche
06426500 Belle Fourche River Below Moorcroft, WY 682 203 149 420 1,761 4,664 2,268 5,169 2,134 997 515 281 19,243

Supporting data and computation results for the data extension process is provided in the .Surface Water Hydrology. technical memorandum.

Natural Flow at Ungaged Model Nodes

The water availability models for this Plan have been developed identifying appropriate locations of model nodes in relation to the various surface water diversion points, return flow locations, and storage reservoirs. Model nodes are located, in large part, at historic streamflow gaging stations in order to take advantage of the historic records of streamflow at these locations. Additionally, it is necessary to locate model nodes at locations with no record of streamflow, to appropriately simulate water use in the various drainages. The locations of the ungaged model nodes are shown on Figure III-6.

The following two methods were used to estimate natural flow at these locations:

  1. Use the recorded streamflow at a downstream streamflow station, adjusting for depletions and storage regulation as well as for the smaller drainage area to estimate natural flow at an upstream location.

  2. Use the regression equations developed by the USGS in WRIR 88-4045, relating drainage area and either average annual precipitation or mean basin elevation to natural flow.
The first method was used for Prairie Dog Creek in the Tongue River basin and Little Piney Creek in the Powder River basin. This method yielded the most reasonable estimates of natural flow for these two locations as evaluated during the calibration of the water availability models. Natural flow at the upstream location is estimated as natural flow at the downstream location multiplied by the proportion of the upstream drainage area to the downstream drainage area. The depletions (diversions minus return flows) used to make the adjustments to the downstream gage records are based on three representative hydrologic conditions (wet, normal, and dry years) and are taken from the water availability modeling work.


click to enlarge

The 1988 USGS report .Streamflows in Wyoming. presents regression equations, which rely on drainage area and average annual precipitation or mean basin elevation to estimate mean annual flow. The equation for the mountainous region is applicable for drainages with mean basin elevations from 5,000 to 10,800 feet. Only one ungaged model node has a mean basin elevation less than 5,000 feet (Prairie Dog Creek with a MBE of 4550). The USGS regression equation for the mountainous region was selected as the most appropriate alternative for estimating natural flow at most of the ungaged model nodes. The regression equation is as follows:

Qa = 0.0015 A1.01 (ELEV/1,000)2.88

Where:Qa is mean annual flow in cubic feet per second,
A is contributing drainage area in square miles, and
ELEV is mean basin elevation in feet.

The reasonableness of the estimates of average annual flow were evaluated by comparing the estimated unit runoff (acre-feet per square mile) to the recorded unit runoff at the nearest natural flow station during the 1970 to 1999 study period. The average annual natural flow was, in some instances, adjusted based on this comparison.

In addition to average annual natural flow at the ungaged model nodes, it is necessary to generate sequential monthly flows at these sites for all years of the study period. This was accomplished by selecting a natural flow gaging station having similar hydrologic characteristics and multiplying the sequential monthly flows at the gaged location by the ratio of the ungaged average annual natural flow to the gaged average annual natural flow. The time distribution of monthly flows at the ungaged sites is, therefore, represented by the streamflow at similar gaged sites. The average monthly and annual streamflows for the 1970 to 1999 study period, for the ungaged model nodes are summarized in Table III-4. The estimated monthly natural flows for each year of the 1970 to 1999 study period are provided in the .Surface Water Hydrology. technical memorandum.

Table III-4
Summary of Average Monthly and Annual Flows (1970 to 1999) -
Ungaged Natural Flow Nodes
Basin Station Name Estimated Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Tongue Rapid Creek Just Below Little Rapid Creek in Section 32, T55N, R85W 98 73 65 58 49 54 156 1,050 1,453 407 169 110 3,742
Beaver Creek at Bottom of Section 26, T55N, R85W 27 20 18 16 14 15 43 290 402 113 47 30 1,034
Soldier Creek at Right Edge of Section 28, T56N, R85W 60 44 39 35 30 33 95 640 886 248 103 67 2,281
Prairie Dog Creek Just Above Dutch Creek in Section 34, T57N, R83W 487 1,314 3,453 2,229 3,493 2,296 1,963 1,560 1,253 886 725 673 20,3321
Powder Red Fork Powder River Just Below North & South Forks Red Fork Powder River in Section 29, T44N, R84W 2,706 2,511 2,415 2,290 2,104 2,477 4,405 9,771 7,396 4,024 3,071 2,695 45,866
Kelly Creek at Top of Section 21, T49N, R82W 73 55 45 36 30 35 132 629 646 228 106 75 2,092
Little North Fork Crazy Woman Creek Just Below Grossett Canyon in Section 14, T49N, R83W 166 125 103 82 69 80 299 1,425 1,463 516 240 170 4,737
Muddy Creek at Diversion Near East Side of Section 35, T49N, R83W 153 115 94 75 63 73 275 1,309 1,344 474 220 156 4,351
Billy Creek at Diversion to O.Malley Draw in Section 13, T48N, R83W 96 79 69 59 52 59 151 481 477 212 125 98 1,957
Little Piney Creek Just Below Bear Gulch in Section 28, T53N, R83W 324 421 625 676 1,295 1,250 811 544 470 309 338 273 7,3361
North & South Forks Shell Creek (Combined), at Confluence of Little North Fork Shell Creek and North Fork Shell Creek in Section 11, and Confluence of Unnamed Tributary & South Fork Shell Creek in Section 14; all in T52N, R83W 56 42 35 28 23 27 114 701 745 219 90 62 2,141
Johnson Creek at Top of Section 22, T51N, R83W 53 41 33 27 22 26 109 672 714 210 86 59 2,052
French Creek at Penrose Ditch Diversion in Section 27, T51N, R83W 128 98 80 64 53 62 262 1,614 1,715 504 207 142 4,928

Note: 1. The monthly and annual flows for Prairie Dog Creek and Little Piney Creek are the average of the dry, normal, and wet year monthly and annual flows.

Streamflows During Wet, Dry, and Normal Years

The water availability models represent dry year, normal year, and wet year hydrologic conditions throughout the Powder/Tongue River Basin. To this end, the annual streamflows for the 1970 to 1999 study period developed through the surface water hydrology work are ranked and divided into these three hydrologic categories. Indicator gages are selected for this purpose, to represent hydrologic conditions for the entire geographic area of the Powder/Tongue River Basin. To the extent possible, natural flow stations, free from transbasin diversion, irrigation depletions, or storage regulation are selected. One exception, Little Powder River above Dry Creek (#06324970) which is impacted by irrigation depletions was selected to represent hydrologic conditions in the Little Powder drainage. The nine indicator gages are shown on Figure III-7.


click to enlarge

Water use in the Tongue River and Powder River are interrelated through transbasin diversions including the Mead Coffeen Ditch, Piney Cruse Ditch, and the Prairie Dog Ditch. Because of this interrelationship, the years selected to represent the various hydrologic conditions must be consistent for all locations within each of these two river basins. Water use in the Little Bighorn River is essentially independent of water use in the other river basins. Similarly, water use in the Little Powder River drainage is also independent of water use in the other drainages. The years with non-exceedance probabilities of 20 percent or less (the driest 20 percent) and the years with exceedance probabilities of 20 percent or less (the wettest 20 percent) at each of the indicator gages are shown in Figure III-8. The remaining 60 percent of the years represent normal years. The years selected to represent dry years, wet years, and normal years for the Little Bighorn River basin, the Tongue and Powder River basins, and the Little Powder River basin are also summarized in Figure III-8.

Figure III-8
Selection of Wet, Dry, and Normal Years for Modeling -
Indicator Stations for the Powder/Tongue River Basins



The average monthly and annual streamflow for the natural flow stations for dry years, normal years, and wet years are provided in Tables III-5, III-6, and III-7 respectively. The average monthly and annual streamflow for the non-natural flow stations for dry years, normal years, and wet years are provided in Tables III-8, III-9, and III-10 respectively. Finally, the average monthly and annual streamflow for the ungaged model nodes for dry years, normal years, and wet years are provided in Tables III-11, III-12, and III-13 respectively.

Table III-5
Summary Of Dry Year Monthly And Annual Flows (1970 To 1999) -
Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06288600 Little Bighorn River Below Dayton Gulch Near Burgess Junction, WY 383 293 270 230 186 199 396 2,737 2,400 1,220 631 406 9,348
06288700 Dry Fork Little Bighorn Below Lick Creek Near Burgess Junction, WY 1,781 1,540 1,467 1,330 1,157 1,254 1,685 4,567 4,393 2,990 2,106 1,666 25,935
06288960 Little Bighorn River Near Parkman, WY 3,804 3,159 2,990 2,746 2,375 2,648 3,934 12,923 11,513 6,948 4,513 3,536 61,087
06288975 Elkhorn Creek Above Fuller Ranch Ditch Near Parkman, WY 104 97 90 81 70 83 145 327 258 145 119 101 1,621
06288990 West Fork Little Bighorn River Near Parkman, WY 911 765 710 645 563 627 872 2,647 2,377 1,526 1,041 824 13,505
06289000 Little Bighorn River at State Line Near Wyola, MT 5,168 4,347 4,130 3,815 3,330 3,687 5,332 16,225 14,538 9,057 6,063 4,832 80,523
06289100 Red Canyon Creek Near Parkman, WY 23 24 19 21 16 23 126 260 103 34 20 21 689
06289800 East Pass Creek Near Parkman, WY 450 377 359 329 293 315 616 1,506 1,362 863 587 468 7,524
06291200 Lodge Grass Creek at State Line Near Wyola, MT 445 356 322 284 238 262 607 2,835 2,606 1,242 690 464 10,349
Tongue
06297000 South Fork Tongue River Near Dayton, WY 1,253 926 859 714 604 671 2,638 15,853 9,285 2,993 1,616 1,228 38,639
06297480 Tongue River at Tongue Canyon Campground Near Dayton, WY 4,618 3,659 3,455 2,989 2,624 2,850 8,122 32,437 20,874 8,460 5,619 4,552 100,258
06298000 Tongue River Near Dayton, WY 4,654 3,681 3,473 3,002 2,633 2,862 8,224 33,196 21,910 9,160 5,672 4,587 103,051
06298480 Little Tongue River at Steamboat Point Near Dayton, WY 119 85 79 65 54 60 335 2,105 1,413 441 190 128 5,073
06298490 Little Tongue River Above South Fork Little Tongue River Near Dayton, WY 85 59 54 44 36 41 209 1,748 926 239 115 83 3,639
06298500 Little Tongue River Near Dayton, WY 200 143 132 108 90 101 528 3,159 2,144 692 306 208 7,811
06299480 Wolf Creek Below Alden Creek Near Wolf, WY 423 313 291 241 205 227 1,036 5,941 4,067 1,352 610 419 15,122
06299490 Wolf Creek Above Red Canyon Creek at Wolf, WY 499 380 355 300 258 284 1,025 5,696 3,926 1,334 610 423 15,089
06299500 Wolf Creek at Wolf, WY 496 370 344 287 244 270 1,106 5,662 3,972 1,426 678 478 15,331
06300500 East Fork Big Goose Creek Near Big Horn, WY 355 243 221 176 143 163 918 6,291 6,407 1,855 700 573 18,042
06301480 Coney Creek Above Twin Lakes Near Big Horn, WY 25 15 13 10 8 9 88 1,282 1,059 153 46 38 2,746
Powder 06309200 Middle Fork Powder River Near Barnum, WY 366 344 335 299 259 320 2,163 5,973 1,485 523 351 336 12,754
06309260 Buffalo Creek Above North Fork Buffalo Creek Near Arminto, WY 23 22 21 18 15 20 211 755 132 36 22 21 1,294
06309270 North Fork Buffalo Creek Near Arminto, WY 70 65 64 57 50 61 387 1,033 269 98 67 64 2,284
06309280 Buffalo Creek Below North Fork Buffalo Creek Near Arminto, WY 0 0 0 0 0 0 10 932 123 3 0 0 1,067
06309450 Beaver Creek Below Bayer Creek Near Barnum, WY 167 145 128 110 89 119 461 804 454 252 180 153 3,060
06309460 Beaver Creek Above White Panther Ditch Near Barnum, WY 600 544 538 521 456 513 889 1,247 860 647 558 508 7,882
06311000 North Fork Powder River Near Hazelton, WY 271 200 155 121 97 116 961 2,983 1,847 587 305 226 7,867
06313950 North Fork Crazy Woman Creek Below Pole Creek Near Buffalo, WY 596 463 368 276 227 260 1,652 4,799 3,037 1,122 596 451 13,847
06314000 North Fork Crazy Woman Creek Near Buffalo, WY 599 475 373 285 232 264 1,648 4,661 3,031 1,127 598 451 13,744
06314500 North Fork Crazy Woman Creek Below Spring Draw Near Buffalo, WY 510 374 287 222 177 212 1,878 6,015 3,677 1,130 577 423 15,483
06315480 Poison Creek Below Tetley Spring Near Mayoworth, WY 209 173 145 117 100 111 453 1,024 717 339 209 169 3,766
06315490 Poison Creek Near Mayoworth, WY 241 202 171 139 120 133 502 1,091 777 382 242 197 4,195
06315500 Middle Fork Crazy Woman Creek Near Greub, WY 659 513 416 339 282 327 1,881 4,814 3,223 1,256 730 569 15,009
06317300 Sourdough Creek Near Buffalo, WY 64 45 36 25 22 28 153 457 433 152 75 56 1,545
06317340 Little Sourdough Creek Near Buffalo, WY 16 11 3 1 1 2 106 95 55 12 5 8 314
06319470 South Rock Creek at Forest Boundary Near Buffalo, WY 414 308 240 189 152 181 1,425 4,299 2,691 882 466 347 11,594
06319480 South Rock Creek Above Red Canyon Near Buffalo, WY 395 293 227 178 143 170 1,383 4,239 2,637 850 445 330 11,228
06319500 South Fork Rock Creek Near Buffalo, WY 751 587 459 371 295 342 2,571 8,859 4,307 1,475 776 606 21,400

Table III-6
Summary Of Normal Year Monthly And Annual Flows (1970 To 1999) -
Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06288600 Little Bighorn River Below Dayton Gulch Near Burgess Junction, WY 422 303 267 237 196 220 361 3,862 6,199 1,629 778 463 14,937
06288700 Dry Fork Little Bighorn Below Lick Creek Near Burgess Junction, WY 1,854 1,591 1,477 1,379 1,227 1,329 1,722 6,442 9,677 4,367 2,630 2,024 35,720
06288960 Little Bighorn River Near Parkman, WY 4,002 3,337 3,079 2,837 2,458 2,766 3,732 17,480 27,873 10,893 6,005 4,414 88,877
06288975 Elkhorn Creek Above Fuller Ranch Ditch Near Parkman, WY 116 101 92 86 75 88 139 470 602 186 136 123 2,213
06288990 West Fork Little Bighorn River Near Parkman, WY 932 790 731 671 589 675 901 3,871 5,812 2,315 1,355 1,037 19,677
06289000 Little Bighorn River at State Line Near Wyola, MT 5,412 4,543 4,226 3,927 3,465 3,879 5,112 21,438 33,132 13,750 7,872 5,948 112,704
06289100 Red Canyon Creek Near Parkman, WY 35 31 25 27 23 42 214 545 241 64 31 27 1,304
06289800 East Pass Creek Near Parkman, WY 474 391 365 339 303 331 552 1,928 2,318 1,057 644 510 9,211
06291200 Lodge Grass Creek at State Line Near Wyola, MT 466 351 310 282 238 273 581 3,838 5,310 1,658 784 529 14,620
Tongue
06297000 South Fork Tongue River Near Dayton, WY 1,462 1,069 976 816 655 749 1,756 14,632 20,914 5,932 2,554 1,700 53,216
06297480 Tongue River at Tongue Canyon Campground Near Dayton, WY 5,140 3,987 3,650 3,349 2,827 3,124 5,922 31,052 40,989 14,721 7,889 5,768 128,419
06298000 Tongue River Near Dayton, WY 5,232 4,031 3,687 3,369 2,853 3,163 6,003 31,944 41,798 15,382 8,019 5,825 131,306
06298480 Little Tongue River at Steamboat Point Near Dayton, WY 137 96 85 74 59 71 239 2,024 2,889 689 280 176 6,819
06298490 Little Tongue River Above South Fork Little Tongue River Near Dayton, WY 102 70 60 52 40 47 133 1,615 2,453 532 202 121 5,427
06298500 Little Tongue River Near Dayton, WY 228 162 140 127 111 124 392 3,153 4,156 1,074 427 278 10,372
06299480 Wolf Creek Below Alden Creek Near Wolf, WY 481 347 306 269 221 261 757 5,691 8,097 2,060 859 561 19,909
06299490 Wolf Creek Above Red Canyon Creek at Wolf, WY 537 404 362 330 272 308 753 5,442 7,717 2,019 857 564 19,565
06299500 Wolf Creek at Wolf, WY 543 405 355 321 281 301 827 5,443 7,591 2,118 934 627 19,746
06300500 East Fork Big Goose Creek Near Big Horn, WY 434 279 208 210 153 169 516 4,890 10,683 3,453 1,208 777 22,980
06301480 Coney Creek Above Twin Lakes Near Big Horn, WY 31 19 13 10 7 9 46 1,069 1,782 423 84 55 3,548
Powder 06309200 Middle Fork Powder River Near Barnum, WY 458 392 362 328 296 434 2,192 9,883 4,450 1,052 528 430 20,805
06309260 Buffalo Creek Above North Fork Buffalo Creek Near Arminto, WY 31 26 23 20 18 29 229 1,337 562 91 37 28 2,429
06309270 North Fork Buffalo Creek Near Arminto, WY 87 74 68 61 55 81 383 1,674 775 195 102 83 3,639
06309280 Buffalo Creek Below North Fork Buffalo Creek Near Arminto, WY 0 0 0 0 0 0 51 1,904 700 41 3 1 2,700
06309450 Beaver Creek Below Bayer Creek Near Barnum, WY 183 160 144 127 117 163 545 1,824 1,026 395 238 186 5,106
06309460 Beaver Creek Above White Panther Ditch Near Barnum, WY 603 555 539 513 479 566 1,040 2,191 1,524 876 673 595 10,154
06311000 North Fork Powder River Near Hazelton, WY 305 230 190 148 127 143 546 3,946 3,634 1,076 481 347 11,173
06313950 North Fork Crazy Woman Creek Below Pole Creek Near Buffalo, WY 670 487 403 316 261 305 1,062 5,365 5,452 1,909 946 698 17,873
06314000 North Fork Crazy Woman Creek Near Buffalo, WY 681 494 412 327 273 313 1,079 5,238 5,249 1,878 934 700 17,577
06314500 North Fork Crazy Woman Creek Below Spring Draw Near Buffalo, WY 581 430 358 268 229 273 1,081 7,809 7,212 2,176 946 671 22,032
06315480 Poison Creek Below Tetley Spring Near Mayoworth, WY 224 179 155 129 114 128 321 1,133 1,112 490 290 233 4,508
06315490 Poison Creek Near Mayoworth, WY 256 207 181 153 134 152 362 1,195 1,174 541 331 268 4,954
06315500 Middle Fork Crazy Woman Creek Near Greub, WY 728 568 492 398 350 426 1,222 5,982 5,545 2,015 1,045 796 19,565
06317300 Sourdough Creek Near Buffalo, WY 73 56 47 36 30 33 96 822 847 265 115 84 2,504
06317340 Little Sourdough Creek Near Buffalo, WY 34 20 7 3 2 5 188 201 133 35 16 25 668
06319470 South Rock Creek at Forest Boundary Near Buffalo, WY 461 353 296 234 199 220 818 5,550 5,256 1,631 730 520 16,268
06319480 South Rock Creek Above Red Canyon Near Buffalo, WY 439 336 278 216 186 208 790 5,473 5,219 1,595 706 502 15,949
06319500 South Fork Rock Creek Near Buffalo, WY 829 650 535 441 374 472 1,688 10,668 9,908 2,619 1,137 897 30,217

Table III-7
Summary Of Wet Year Monthly And Annual Flows (1970 To 1999) -
Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06288600 Little Bighorn River Below Dayton Gulch Near Burgess Junction, WY 404 293 265 246 199 212 299 3,733 10,128 2,551 981 538 19,851
06288700 Dry Fork Little Bighorn Below Lick Creek Near Burgess Junction, WY 1,921 1,678 1,583 1,455 1,301 1,407 1,696 7,747 15,057 7,010 3,406 2,525 46,785
06288960 Little Bighorn River Near Parkman, WY 4,222 3,588 3,245 3,076 2,707 2,977 3,723 21,474 45,028 18,889 8,210 5,703 122,841
06288975 Elkhorn Creek Above Fuller Ranch Ditch Near Parkman, WY 118 102 95 89 81 92 136 715 1,125 327 159 157 3,196
06288990 West Fork Little Bighorn River Near Parkman, WY 984 836 764 707 647 710 901 5,327 10,134 4,021 1,785 1,335 28,152
06289000 Little Bighorn River at State Line Near Wyola, MT 5,667 4,890 4,467 4,217 3,748 4,120 5,097 26,348 54,728 23,118 10,465 7,502 152,367
06289100 Red Canyon Creek Near Parkman, WY 55 48 40 44 36 66 346 1,002 424 109 51 42 2,263
06289800 East Pass Creek Near Parkman, WY 464 387 372 344 313 330 455 2,223 3,454 1,392 706 557 10,995
06291200 Lodge Grass Creek at State Line Near Wyola, MT 466 344 322 308 257 270 427 3,807 8,850 2,869 913 624 19,456
Tongue
06297000 South Fork Tongue River Near Dayton, WY 1,479 1,030 923 856 690 786 1,288 14,366 39,809 11,430 3,358 1,954 77,970
06297480 Tongue River at Tongue Canyon Campground Near Dayton, WY 5,280 4,056 3,710 3,440 3,012 3,311 4,758 29,952 68,799 25,483 9,988 6,407 168,195
06298000 Tongue River Near Dayton, WY 5,301 3,998 3,673 3,465 2,930 3,237 4,697 30,887 68,594 25,504 10,027 6,591 168,904
06298480 Little Tongue River at Steamboat Point Near Dayton, WY 139 97 84 74 62 72 194 2,648 5,358 1,124 339 177 10,367
06298490 Little Tongue River Above South Fork Little Tongue River Near Dayton, WY 98 65 56 52 41 49 90 1,614 4,929 1,122 280 141 8,538
06298500 Little Tongue River Near Dayton, WY 240 161 143 132 104 120 303 3,874 7,901 1,805 548 296 15,626
06299480 Wolf Creek Below Alden Creek Near Wolf, WY 488 351 314 284 228 267 617 7,299 14,248 3,542 1,089 585 29,311
06299490 Wolf Creek Above Red Canyon Creek at Wolf, WY 568 429 380 357 304 332 636 6,999 13,552 3,453 1,068 586 28,664
06299500 Wolf Creek at Wolf, WY 568 412 369 336 272 317 683 6,843 13,155 3,405 1,153 657 28,171
06300500 East Fork Big Goose Creek Near Big Horn, WY 471 342 254 217 169 187 320 5,517 16,433 6,483 1,155 587 32,133
06301480 Coney Creek Above Twin Lakes Near Big Horn, WY 33 19 15 12 9 11 21 965 2,498 1,252 116 37 4,987
Powder 06309200 Middle Fork Powder River Near Barnum, WY 543 561 427 373 329 497 1,886 13,410 11,223 1,624 703 542 32,117
06309260 Buffalo Creek Above North Fork Buffalo Creek Near Arminto, WY 38 40 27 22 19 33 194 1,984 1,426 194 58 36 4,070
06309270 North Fork Buffalo Creek Near Arminto, WY 102 109 81 70 60 91 313 2,141 1,981 317 143 111 5,518
06309280 Buffalo Creek Below North Fork Buffalo Creek Near Arminto, WY 0 0 0 0 0 0 7 2,947 2,525 133 1 0 5,612
06309450 Beaver Creek Below Bayer Creek Near Barnum, WY 209 204 155 138 118 174 499 2,662 2,173 708 343 251 7,634
06309460 Beaver Creek Above White Panther Ditch Near Barnum, WY 652 633 577 531 487 593 975 3,236 2,937 1,278 898 756 13,553
06311000 North Fork Powder River Near Hazelton, WY 286 213 174 157 120 169 415 4,497 7,433 1,738 607 360 16,167
06313950 North Fork Crazy Woman Creek Below Pole Creek Near Buffalo, WY 542 449 359 315 272 329 874 7,018 9,478 3,068 1,159 683 24,544
06314000 North Fork Crazy Woman Creek Near Buffalo, WY 557 448 366 314 275 331 875 7,077 9,409 3,174 1,220 724 24,767
06314500 North Fork Crazy Woman Creek Below Spring Draw Near Buffalo, WY 539 398 324 291 221 314 798 9,188 15,384 3,455 1,171 684 32,766
06315480 Poison Creek Below Tetley Spring Near Mayoworth, WY 192 165 140 130 116 136 314 1,436 1,721 642 318 222 5,530
06315490 Poison Creek Near Mayoworth, WY 222 191 167 153 139 165 350 1,485 1,805 704 365 253 5,997
06315500 Middle Fork Crazy Woman Creek Near Greub, WY 692 540 460 422 338 447 903 6,697 10,221 3,060 1,289 838 25,906
06317300 Sourdough Creek Near Buffalo, WY 66 50 41 37 29 40 94 953 1,555 379 137 83 3,462
06317340 Little Sourdough Creek Near Buffalo, WY 65 39 13 5 3 9 359 373 242 62 28 43 1,242
06319470 South Rock Creek at Forest Boundary Near Buffalo, WY 437 337 274 244 187 244 621 6,203 10,264 2,837 914 545 23,106
06319480 South Rock Creek Above Red Canyon Near Buffalo, WY 417 325 262 238 180 232 599 6,175 10,222 2,742 882 516 22,788
06319500 South Fork Rock Creek Near Buffalo, WY 763 595 490 422 353 437 1,450 11,665 17,560 4,334 1,506 916 40,490

Table III-8
Summary of Dry Year Monthly and Annual Flows (1970 To 1999) -
Non-Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06289600 West Pass Creek Near Parkman, WY 522 485 460 421 377 469 647 1,126 1,038 584 406 415 6,949
06289820 East Pass Creek Near Dayton, WY 620 578 551 506 458 592 790 1,407 1,317 673 398 475 8,364
06289870 Twin Creek Near Parkman, WY 71 64 81 213 155 472 573 664 160 93 70 59 2,676
Tongue
06302000 Big Goose Creek Near Sheridan, WY 2,116 1,637 1,536 1,310 1,136 1,244 2,545 14,220 14,547 5,167 3,833 2,937 52,227
06303500 Little Goose Creek in Canyon Near Big Horn, WY 1,738 1,352 1,271 1,087 945 1,033 2,160 9,517 7,440 5,127 3,802 2,395 37,866
06305500 Goose Creek Below Sheridan, WY 6,048 5,421 4,763 4,009 3,664 6,136 6,965 20,947 16,605 3,094 2,118 2,882 82,651
06305700 Goose Creek Near Acme, WY 6,185 5,536 4,858 4,084 3,730 6,277 7,133 21,677 17,157 3,147 2,146 2,927 84,857
06306250 Prairie Dog Creek Near Acme, WY 2,437 1,924 1,611 1,129 2,253 5,008 2,043 1,678 1,279 878 1,552 1,928 23,719
06306300 Tongue River at State Line Near Decker, MT 14,045 12,138 8,888 8,018 8,497 16,247 19,902 61,280 43,982 10,638 6,433 7,775 217,843
Powder
06309500 Middle Fork Powder River Above Kaycee, WY 2,616 2,537 2,419 2,362 2,125 2,471 5,738 10,427 4,480 2,483 2,065 2,177 41,898
06311060 North Fork Powder River Below Bull Creek Near Hazelton, WY 238 137 131 117 104 134 415 2,289 2,342 2,011 1,313 719 9,949
06311400 North Fork Powder River Below Pass Creek Near Mayoworth, WY 1,348 1,128 1,160 1,145 1,008 1,105 1,672 3,450 2,843 2,598 2,122 1,548 21,128
06312500 Powder River Near Kaycee, WY 3,984 5,116 5,210 4,358 5,231 6,568 7,052 18,405 10,431 643 850 1,268 69,116
06313000 South Fork Powder River Near Kaycee, WY 86 118 116 102 1,136 3,680 2,856 5,383 1,170 269 1,000 6 15,923
06313400 Salt Creek Near Sussex, WY 1,962 1,848 1,795 1,885 2,721 2,888 2,282 2,930 2,355 2,618 1,773 1,885 26,941
06313500 Powder River at Sussex, WY 6,572 7,446 7,294 6,924 9,824 12,733 11,749 17,875 6,632 5,191 3,572 2,639 98,450
SEO Gage Crazy Woman Creek at Trabing Bridge Near Buffalo, WY 330 204 221 210 153 193 1,013 1,442 1,788 852 607 293 7,307
06316400 Crazy Woman Creek at Upper Station Near Arvada, WY 1,073 1,174 1,125 1,024 1,198 1,904 2,181 3,773 2,521 792 423 278 17,466
06317000 Powder River at Arvada, WY 7,643 8,622 7,085 7,065 10,102 18,663 13,967 21,182 9,420 5,767 2,810 2,314 114,639
06318500 Clear Creek Near Buffalo, WY 1,806 1,397 1,062 778 621 912 2,633 9,770 11,330 5,321 2,680 1,977 40,287
SEO Gage Clear Creek in Buffalo City Park Buffalo, WY 1,168 1,174 1,195 949 1,419 1,700 2,507 6,059 5,297 1,360 525 600 23,951
06320000 Rock Creek Near Buffalo, WY 826 623 581 489 419 461 1,248 5,991 4,429 2,886 2,113 990 21,055
SEO Gage Rock Creek at Mouth Near Buffalo, WY 1,054 1,042 961 822 1,067 1,851 1,141 3,790 1,495 616 506 708 15,052
06320200 Clear Creek Below Rock Creek Near Buffalo, WY 3,157 2,766 2,312 1,853 2,020 3,282 4,667 9,945 7,571 2,407 1,211 1,518 42,708
SEO Gage Clear Creek Below Healy Reservoir Near Buffalo, WY 1,647 1,448 1,248 1,052 1,480 2,101 3,662 8,955 6,790 3,071 1,722 1,527 34,703
06321000 South Piney Creek Near Story, WY 1,735 1,225 1,214 1,033 803 895 1,370 4,880 16,184 9,925 7,096 4,360 50,719
06323000 Piney Creek at Kearney, WY 1,401 1,985 1,785 1,713 1,514 1,740 4,029 12,630 8,558 2,033 784 497 38,670
SEO Gage Little Piney Creek, WY 766 760 636 627 589 941 809 1,082 623 660 538 586 8,616
SEO Gage Piney Creek Below Lake DeSmet Tunnel Intake Near Story, WY 974 552 422 387 356 458 2,180 8,305 6,194 2,871 1,073 1,094 24,865
06323500 Piney Creek at Ucross, WY 3,235 3,416 3,367 3,181 1,307 1,717 3,657 7,110 8,503 7,061 4,634 3,715 50,904
SEO Gage Clear Creek at Double Crossing Near Clearmont, WY 7,063 7,196 6,881 6,323 5,321 6,584 7,413 15,042 12,668 8,499 6,054 5,085 94,127
SEO Gage Clear Creek Below P&F#3 Ditch Near Clearmont, WY 10,045 7,190 3,181 3,300 7,712 9,831 10,268 38,389 61,603 13,948 5,051 4,132 174,649
06324000 Clear Creek Near Arvada, WY 6,687 6,744 5,449 5,313 4,172 8,956 8,859 13,104 9,400 4,922 3,449 3,796 80,849
06324500 Powder River at Moorhead, MT 15,447 16,172 10,265 11,567 13,510 27,822 22,040 33,420 20,735 10,368 6,822 5,603 193,770
Little Powder 06324890 Little Powder River Below Corral Creek Near Weston, WY 2 12 16 22 89 278 41 296 39 63 9 0 868
06324925 Little Powder River Near Weston, WY 19 26 30 24 319 399 284 474 220 64 169 13 2,041
06324970 Little Powder River Above Dry Creek Near Weston, WY 41 54 69 60 481 630 480 737 383 127 111 17 3,189
Belle
Fourche
06426500 Belle Fourche River Below Moorcroft, WY 26 70 61 41 464 1,460 299 443 212 1,189 183 71 4,517

Table III-9
Summary of Normal Year Monthly and Annual Flows (1970 To 1999) -
Non-Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06289600 West Pass Creek Near Parkman, WY 504 467 437 411 417 498 799 2,160 2,006 825 529 501 9,554
06289820 East Pass Creek Near Dayton, WY 596 562 544 528 542 635 982 2,882 2,855 883 494 512 12,016
06289870 Twin Creek Near Parkman, WY 124 105 137 370 270 783 909 1,820 398 173 129 98 5,316
Tongue
06302000 Big Goose Creek Near Sheridan, WY 2,326 1,735 1,570 1,430 1,194 1,339 2,282 12,149 25,660 7,537 4,754 3,721 65,698
06303500 Little Goose Creek in Canyon Near Big Horn, WY 1,847 1,384 1,250 1,126 945 1,057 2,189 10,298 14,356 6,323 5,629 3,521 49,924
06305500 Goose Creek Below Sheridan, WY 6,814 5,975 5,231 4,636 5,507 5,947 8,728 23,311 37,384 8,686 4,240 6,047 122,506
06305700 Goose Creek Near Acme, WY 6,974 6,107 5,341 4,729 5,627 6,080 8,953 24,129 38,842 8,919 4,325 6,185 126,210
06306250 Prairie Dog Creek Near Acme, WY 2,839 2,208 1,848 1,309 2,689 5,514 2,968 2,928 2,289 1,335 1,630 2,521 30,078
06306300 Tongue River at State Line Near Decker, MT 16,788 14,097 12,116 12,437 15,327 19,950 22,686 66,751 92,276 27,317 11,874 14,461 326,123
Powder
06309500 Middle Fork Powder River Above Kaycee, WY 2,833 2,582 2,475 2,381 2,258 2,727 5,709 15,043 9,203 3,998 2,751 2,576 54,536
06311060 North Fork Powder River Below Bull Creek Near Hazelton, WY 240 178 167 130 119 141 363 3,099 3,867 1,850 1,470 1,096 12,720
06311400 North Fork Powder River Below Pass Creek Near Mayoworth, WY 1,303 1,116 1,119 1,084 971 1,069 1,688 4,781 5,035 2,692 2,343 1,915 25,116
06312500 Powder River Near Kaycee, WY 4,911 6,163 6,250 5,456 6,193 8,182 8,671 27,220 16,087 1,025 811 1,775 92,743
06313000 South Fork Powder River Near Kaycee, WY 159 215 149 166 1,198 7,158 5,540 8,230 1,974 608 1,676 11 27,086
06313400 Salt Creek Near Sussex, WY 2,235 1,706 1,580 1,726 2,412 3,985 3,012 4,564 4,661 2,916 1,876 1,750 32,423
06313500 Powder River at Sussex, WY 8,804 8,411 7,030 6,999 11,096 18,936 19,424 33,736 24,225 8,661 4,715 5,703 157,741
SEO Gage Crazy Woman Creek at Trabing Bridge Near Buffalo, WY 324 221 215 186 144 182 1,589 8,734 10,816 2,724 959 1,084 27,177
06316400 Crazy Woman Creek at Upper Station Near Arvada, WY 1,419 1,319 961 811 1,793 2,626 3,724 8,073 7,100 2,075 1,083 974 31,956
06317000 Powder River at Arvada, WY 9,874 9,343 6,922 6,424 12,141 24,059 23,302 44,564 38,014 13,330 6,608 6,543 201,124
06318500 Clear Creek Near Buffalo, WY 2,258 1,534 1,184 881 742 970 2,622 11,564 17,291 7,889 3,941 2,840 53,714
SEO Gage Clear Creek in Buffalo City Park Buffalo, WY 1,413 1,131 871 736 924 1,738 2,159 9,095 13,292 4,229 1,565 1,501 38,653
06320000 Rock Creek Near Buffalo, WY 893 651 578 519 431 485 946 6,726 8,800 3,682 2,774 1,684 28,169
SEO Gage Rock Creek at Mouth Near Buffalo, WY 1,401 1,292 952 870 1,214 2,267 1,322 4,706 6,204 1,592 957 925 23,702
06320200 Clear Creek Below Rock Creek Near Buffalo, WY 3,910 3,267 2,698 2,618 3,170 4,190 5,369 16,040 22,192 7,063 3,307 3,584 77,409
SEO Gage Clear Creek Below Healy Reservoir Near Buffalo, WY 1,916 1,373 996 831 1,044 2,262 3,532 13,057 19,113 7,319 3,615 3,025 58,083
06321000 South Piney Creek Near Story, WY 2,011 1,524 1,491 1,217 908 968 1,493 5,891 19,901 11,386 8,790 5,621 61,201
06323000 Piney Creek at Kearney, WY 1,866 2,259 2,118 1,854 1,603 2,138 4,087 15,123 22,767 4,996 1,897 1,497 62,203
SEO Gage Little Piney Creek, WY 744 722 580 549 707 950 954 1,428 1,428 803 584 718 10,166
SEO Gage Piney Creek Below Lake DeSmet Tunnel Intake Near Story, WY 1,463 1,057 713 642 595 861 1,678 9,173 18,866 4,704 2,047 1,432 43,231
06323500 Piney Creek at Ucross, WY 3,045 3,150 2,126 1,851 1,543 2,979 3,926 12,380 17,789 5,885 4,958 3,896 63,527
SEO Gage Clear Creek at Double Crossing Near Clearmont, WY 7,147 6,939 5,087 4,263 5,128 9,624 9,332 24,775 37,299 11,948 7,645 7,449 136,634
SEO Gage Clear Creek Below P&F#3 Ditch Near Clearmont, WY 6,599 5,483 4,320 4,630 6,173 10,641 7,800 19,529 38,577 12,655 6,281 5,376 128,064
06324000 Clear Creek Near Arvada, WY 6,461 6,176 4,147 3,680 5,852 10,041 10,320 23,374 34,407 9,106 5,364 6,169 125,097
06324500 Powder River at Moorhead, MT 16,672 14,954 10,739 10,319 20,648 36,869 31,922 62,461 71,190 23,837 11,879 12,535 324,023
Little Powder 06324890 Little Powder River Below Corral Creek Near Weston, WY 8 14 21 60 187 713 138 837 84 296 41 0 2,399
06324925 Little Powder River Near Weston, WY 283 144 65 405 1,109 1,553 1,119 1,970 1,683 625 309 246 9,511
06324970 Little Powder River Above Dry Creek Near Weston, WY 450 254 142 548 1,493 2,209 1,519 2,318 2,026 812 453 360 12,582
Belle
Fourche
06426500 Belle Fourche River Below Moorcroft, WY 846 276 205 494 1,513 3,406 2,128 2,920 1,675 804 418 376 15,059

Table III-10
Summary of Wet Year Monthly and Annual Flows (1970 To 1999) -
Non-Natural Flow Stations
Basin Station Number Station Name Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Little Bighorn
06289600 West Pass Creek Near Parkman, WY 580 489 427 437 397 554 790 2,821 3,336 1,121 468 608 12,027
06289820 East Pass Creek Near Dayton, WY 710 600 520 549 484 684 1,035 3,727 4,598 1,411 517 721 15,555
06289870 Twin Creek Near Parkman, WY 201 171 218 631 444 1,621 1,779 3,801 735 309 233 170 10,314
Tongue
06302000 Big Goose Creek Near Sheridan, WY 2,438 1,792 1,633 1,532 1,276 1,423 1,844 15,206 43,642 15,021 5,115 4,027 94,948
06303500 Little Goose Creek in Canyon Near Big Horn, WY 1,998 1,477 1,349 1,267 1,059 1,178 1,681 13,765 23,622 8,813 5,493 4,168 65,872
06305500 Goose Creek Below Sheridan, WY 6,969 5,930 5,088 4,932 4,673 7,138 8,270 43,156 71,740 21,424 5,397 6,955 191,672
06305700 Goose Creek Near Acme, WY 7,133 6,062 5,193 5,033 4,767 7,306 8,477 44,499 75,198 22,253 5,480 7,142 198,542
06306250 Prairie Dog Creek Near Acme, WY 3,018 2,448 2,050 1,394 2,556 7,069 3,027 8,112 3,531 2,223 2,239 2,309 39,972
06306300 Tongue River at State Line Near Decker, MT 16,527 14,165 11,352 10,340 10,940 21,038 21,378 108,313 172,233 55,478 16,727 15,543 473,035
Powder
06309500 Middle Fork Powder River Above Kaycee, WY 2,946 2,927 2,605 2,432 2,273 2,817 5,514 18,856 15,840 5,414 3,479 3,002 68,105
06311060 North Fork Powder River Below Bull Creek Near Hazelton, WY 241 175 161 139 133 159 332 4,356 6,662 2,508 1,899 1,134 17,899
06311400 North Fork Powder River Below Pass Creek Near Mayoworth, WY 1,370 1,215 1,178 1,153 1,048 1,133 1,330 6,663 9,603 3,500 2,898 2,293 33,386
06312500 Powder River Near Kaycee, WY 6,596 8,318 8,443 7,304 8,391 10,965 11,653 35,264 20,683 1,310 1,157 2,323 122,407
06313000 South Fork Powder River Near Kaycee, WY 277 394 234 331 1,879 12,398 9,830 14,619 3,052 854 2,431 15 46,315
06313400 Salt Creek Near Sussex, WY 2,618 2,134 1,994 2,179 2,928 6,372 3,697 10,353 4,264 3,944 2,299 2,130 44,913
06313500 Powder River at Sussex, WY 17,455 10,548 8,768 8,082 9,846 19,191 17,354 73,310 51,299 14,882 4,663 4,747 240,144
SEO Gage Crazy Woman Creek at Trabing Bridge Near Buffalo, WY 342 248 227 213 167 205 2,705 16,980 32,197 7,031 2,723 1,346 64,382
06316400 Crazy Woman Creek at Upper Station Near Arvada, WY 3,113 1,647 1,174 970 1,556 2,802 3,577 20,742 21,055 3,967 2,082 646 63,330
06317000 Powder River at Arvada, WY 18,455 11,577 8,322 7,527 11,060 27,253 22,005 105,460 90,540 25,422 8,175 5,057 340,852
06318500 Clear Creek Near Buffalo, WY 2,683 1,917 1,485 1,122 948 1,224 3,052 17,066 25,968 14,208 5,142 3,249 78,065
SEO Gage Clear Creek in Buffalo City Park Buffalo, WY 4,025 2,420 1,881 1,577 2,194 2,946 3,054 15,386 25,177 9,248 1,853 1,168 70,930
06320000 Rock Creek Near Buffalo, WY 964 688 622 579 474 535 878 9,368 14,881 5,068 3,209 1,747 39,012
SEO Gage Rock Creek at Mouth Near Buffalo, WY 2,602 1,694 1,311 1,205 1,650 2,571 1,691 9,391 15,501 3,386 1,269 1,104 43,372
06320200 Clear Creek Below Rock Creek Near Buffalo, WY 3,474 3,091 2,449 2,224 2,341 4,567 5,969 27,998 41,149 14,336 4,037 3,100 114,733
SEO Gage Clear Creek Below Healy Reservoir Near Buffalo, WY 5,612 3,084 2,263 1,852 2,658 3,530 4,435 26,501 39,607 14,794 4,335 3,255 111,926
06321000 South Piney Creek Near Story, WY 2,333 1,720 1,708 1,457 1,168 1,244 1,749 6,581 22,873 17,609 10,733 5,829 75,004
06323000 Piney Creek at Kearney, WY 2,432 2,775 2,159 2,103 1,710 2,037 4,070 20,980 41,967 13,590 3,830 1,340 98,991
SEO Gage Little Piney Creek, WY 925 830 582 642 833 1,030 1,054 2,734 2,540 1,336 722 707 13,933
SEO Gage Piney Creek Below Lake DeSmet Tunnel Intake Near Story, WY 2,259 1,558 1,144 1,004 927 1,280 2,549 17,464 38,497 10,973 3,374 1,762 82,791
06323500 Piney Creek at Ucross, WY 4,880 4,201 3,459 3,078 2,221 4,190 4,203 18,650 42,300 14,719 6,525 3,190 111,616
SEO Gage Clear Creek at Double Crossing Near Clearmont, WY 13,916 9,888 8,067 6,929 8,629 11,825 10,678 47,150 86,491 28,773 8,955 6,602 247,901
SEO Gage Clear Creek Below P&F#3 Ditch Near Clearmont, WY 5,842 5,553 2,924 2,797 4,373 12,829 12,513 17,547 3,355 2,034 589 1,452 71,807
06324000 Clear Creek Near Arvada, WY 9,179 7,200 3,891 4,404 7,135 10,514 11,838 45,277 78,252 26,470 7,949 5,007 217,115
06324500 Powder River at Moorhead, MT 24,643 19,325 9,172 12,118 19,360 42,163 31,243 146,877 162,267 53,775 16,330 9,263 546,537
Little Powder 06324890 Little Powder River Below Corral Creek Near Weston, WY 11 27 37 83 261 2,693 233 3,385 225 387 58 1 7,400
06324925 Little Powder River Near Weston, WY 2,316 180 143 562 9,553 16,317 6,268 9,079 2,733 377 279 53 47,860
06324970 Little Powder River Above Dry Creek Near Weston, WY 2,722 485 375 1,195 7,548 14,241 2,977 13,336 3,498 1,177 553 323 48,430
Belle
Fourche
06426500 Belle Fourche River Below Moorcroft, WY 850 118 70 577 3,802 11,643 4,656 16,641 5,432 1,384 1,138 208 46,519

Table III-11
Summary of Dry Year Monthly and Annual Flows (1970 To 1999) -
Ungaged Natural Flow Nodes
Basin Station Name Estimated Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Tongue Rapid Creek Just Below Little Rapid Creek in Section 32, T55N, R85W 90 67 63 52 44 49 201 1,031 723 260 123 87 2,792
Beaver Creek at Bottom of Section 26, T55N, R85W 25 19 17 14 12 14 56 285 200 72 34 24 771
Soldier Creek at Right Edge of Section 28, T56N, R85W 55 41 38 32 27 30 123 628 441 158 75 53 1,702
Prairie Dog Creek Just Above Dutch Creek in Section 34, T57N, R83W 462 1,322 3,269 2,125 1,827 1,432 1,401 1,314 1,134 748 612 610 16,255
Powder Red Fork Powder River Just Below North & South Forks Red Fork Powder River in Section 29, T44N, R84W 24 24 19 20 15 23 118 335 105 33 18 17 752
Kelly Creek at Top of Section 21, T49N, R82W 49 37 28 22 18 21 173 531 330 106 56 41 1,414
Little North Fork Crazy Woman Creek Just Below Grossett Canyon in Section 14, T49N, R83W 156 123 97 74 60 68 428 1,210 787 292 155 117 3,568
Muddy Creek at Diversion Near East Side of Section 35, T49N, R83W 143 113 89 68 55 63 393 1,111 723 269 143 108 3,277
Billy Creek at Diversion to O.Malley Draw in Section 13, T48N, R83W 2,116 1,637 1,536 1,310 1,136 1,244 2,545 14,220 14,547 5,167 3,833 2,937 52,227
Little Piney Creek Just Below Bear Gulch in Section 28, T53N, R83W 332 336 601 616 820 626 564 407 341 245 309 282 5,480
North & South Forks Shell Creek (Combined), at Confluence of Little North Fork Shell Creek and North Fork Shell Creek in Section 11, and Confluence of Unnamed Tributary & South Fork Shell Creek in Section 14; all in T52N, R83W 52 38 30 23 19 22 181 554 345 111 58 43 1,475
Johnson Creek at Top of Section 22, T51N, R83W 49 37 28 22 18 21 173 531 330 106 56 41 1,414
French Creek at Penrose Ditch Diversion in Section 27, T51N, R83W 119 88 68 53 43 51 416 1,275 793 256 134 99 3,395

Table III-12
Summary of Normal Year Monthly and Annual Flows (1970 To 1999) -
Ungaged Natural Flow Nodes
Basin Station Name Estimated Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Tongue Rapid Creek Just Below Little Rapid Creek in Section 32, T55N, R85W 99 74 65 58 51 55 151 991 1,382 386 170 114 3,596
Beaver Creek at Bottom of Section 26, T55N, R85W 27 20 18 16 14 15 42 274 382 107 47 32 994
Soldier Creek at Right Edge of Section 28, T56N, R85W 60 45 39 36 31 33 92 604 843 235 104 70 2,192
Prairie Dog Creek Just Above Dutch Creek in Section 34, T57N, R83W 559 1,529 3,372 2,321 2,368 2,074 1,852 1,470 1,202 1,066 830 752 19,396
Powder Red Fork Powder River Just Below North & South Forks Red Fork Powder River in Section 29, T44N, R84W 34 31 25 27 23 41 215 515 238 64 32 28 1,272
Kelly Creek at Top of Section 21, T49N, R82W 55 42 35 27 23 26 99 685 654 200 88 63 1,998
Little North Fork Crazy Woman Creek Just Below Grossett Canyon in Section 14, T49N, R83W 177 128 107 85 71 81 280 1,360 1,363 488 243 182 4,563
Muddy Creek at Diversion Near East Side of Section 35, T49N, R83W 162 118 98 78 65 75 257 1,249 1,252 448 243 182 4,563
Billy Creek at Diversion to O.Malley Draw in Section 13, T48N, R83W 2,326 1,735 1,570 1,430 1,194 1,339 2,282 12,149 25,660 7,537 4,754 3,721 65,698
Little Piney Creek Just Below Bear Gulch in Section 28, T53N, R83W 298 422 610 672 1,086 1,143 678 483 465 271 309 264 6,691
North & South Forks Shell Creek (Combined), at Confluence of Little North Fork Shell Creek and North Fork Shell Creek in Section 11, and Confluence of Unnamed Tributary & South Fork Shell Creek in Section 14; all in T52N, R83W 57 44 36 28 24 27 103 715 682 208 92 66 2,084
Johnson Creek at Top of Section 22, T51N, R83W 55 42 35 27 23 26 99 685 654 200 88 63 1,998
French Creek at Penrose Ditch Diversion in Section 27, T51N, R83W 132 101 84 65 56 63 237 1,646 1,570 480 212 151 4,797

Table III-13
Summary of Wet Year Monthly and Annual Flows (1970 To 1999) -
Ungaged Natural Flow Nodes
Basin Station Name Estimated Average Streamflow for 1970-1999 in Acre-Feet
Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Annual
Tongue Rapid Creek Just Below Little Rapid Creek in Section 32, T55N, R85W 103 75 67 61 50 58 124 1,246 2,396 620 210 210 5,130
Beaver Creek at Bottom of Section 26, T55N, R85W 29 21 19 17 14 16 34 344 662 171 58 33 1,418
Soldier Creek at Right Edge of Section 28, T56N, R85W 63 46 41 37 30 35 76 760 1,460 378 128 73 3,127
Prairie Dog Creek Just Above Dutch Creek in Section 34, T57N, R83W 439 1,090 3,718 2,241 6,284 3,382 2,637 1,896 1,423 845 733 657 25,344
Powder Red Fork Powder River Just Below North & South Forks Red Fork Powder River in Section 29, T44N, R84W 50 44 36 41 33 60 316 925 390 100 46 39 2,081
Kelly Creek at Top of Section 21, T49N, R82W 52 41 33 30 23 29 75 773 1,280 343 110 65 2,854
Little North Fork Crazy Woman Creek Just Below Grossett Canyon in Section 14, T49N, R83W 145 116 95 81 71 86 227 1,837 2,442 824 317 188 6,429
Muddy Creek at Diversion Near East Side of Section 35, T49N, R83W 133 107 87 75 66 79 209 1,687 2,243 757 291 173 5,905
Billy Creek at Diversion to O.Malley Draw in Section 13, T48N, R83W 2,438 1,792 1,633 1,532 1,276 1,423 1,844 15,206 43,642 15,021 5,115 4,027 94,948
Little Piney Creek Just Below Bear Gulch in Section 28, T53N, R83W 351 505 664 740 1,979 1,982 1,190 741 604 411 397 271 9,837
North & South Forks Shell Creek (Combined), at Confluence of Little North Fork Shell Creek and North Fork Shell Creek in Section 11, and Confluence of Unnamed Tributary & South Fork Shell Creek in Section 14; all in T52N, R83W 54 42 34 31 24 30 78 807 1,336 358 115 67 2,978
Johnson Creek at Top of Section 22, T51N, R83W 52 41 33 30 23 29 75 773 1,280 343 110 65 2,854
French Creek at Penrose Ditch Diversion in Section 27, T51N, R83W 125 98 79 71 54 70 180 1,857 3,074 825 265 155 6,854

Spreadsheet Model Development and Calibration

Water availability spreadsheet models were developed for the following six sub-basins within the Powder/Tongue River Basin planning area:

The models do not explicitly account for water rights, appropriations, or compact allocations nor are the models operated based on these legal constraints. Further, the models do not associate supplemental reservoir releases to the specific water users. However, by calibrating the models to historical streamflows at gaged locations, the models can be used to generally represent existing operations.

The models developed for this plan are intended to simulate water use and availability under existing conditions. For each Powder/Tongue River sub-basin, three models were developed, reflecting each of the three hydrologic conditions (dry, normal, and wet years). The models each represent one calendar year of flows, on a monthly time step. Streamflow, estimated actual diversions, full supply diversions, irrigation returns, and reservoir conditions are the basic input data to the models. For all of these data, average values drawn from the dry, normal, or wet years of the study period were computed for use in the spreadsheets.

Theoretical Maximum Diversion Requirements were calculated using the acreage of irrigated lands mapped through this study and the consumptive irrigation requirements (CIR) provided by Dr. Larry Pochop. The historical diversion records were then compared to the Theoretical Maximum Diversions yielding mathematical relationships used to calculate the Estimated Actual Diversions and the Full Supply Diversion Requirements for all modeled irrigated lands. A more detailed discussion of this process is offered in the .Agricultural Use. technical memorandum.

Development of the model and the model inputs (primarily streamflows, estimated actual diversions and the interrelated irrigation efficiencies and irrigation return flows) progressed somewhat concurrently in order to achieve calibration. The model representation of the physical system and the various model inputs were adjusted as necessary through a trial and error process until the models were reasonably well calibrated.

To mathematically represent each sub-basin, the river system was divided into reaches based primarily upon the location of major tributary confluences. Each reach was then sub-divided by identifying a series of individual nodes representing diversions, reservoirs, tributary confluences, gages, or other significant water resources features. The resulting network is a simplified representation of actual conditions. Figures III-9 through III-14 present node diagrams of the sub-basin models developed for the planning area.


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Historical or virgin flow for each month is supplied to the model at the uppermost node. Where available, upper basin gages were selected as the uppermost model nodes; in their absence, flow at the ungaged headwater point was estimated as discussed in a preceding section. For each reach, incremental stream gains (e.g., ungaged tributaries, ground water inflow, and inflow resulting from man-induced but unmodeled processes) and losses (e.g. seepage, evaporation, and unspecified diversions) are computed by the spreadsheet. These are calculated by adding the net modeled effects (diversions and increases in storage less return flows and decreases in storage) within the basin back into the difference between the upstream and downstream historical gage flows.

At each node, a water budget computation is completed to determine the amount of water that bypasses the node. At non-storage nodes, the difference between inflow, including upstream inflows, return flows, imports and basin gains, and outflows, including diversions, basin losses and exports, is the amount of flow available to the next node downstream. For storage nodes, an additional loss calculation for evaporation and the change in storage is evaluated. Also at storage nodes, any uncontrolled spill that occurs is added to the scheduled release to determine total outflow. Diverted amounts at diversion nodes are the minimum of demand (the full supply diversion at the structure) and physically available streamflow. The mass balance, or water budget calculations, is performed for all nodes in a reach.

Model output includes the full-supply diversion demand and model simulated diversions at each of the diversion points, and streamflow at each of the Powder/Tongue River sub-basin model nodes. Estimates of impacts associated with various water projects can be analyzed by changing input data, as decreases in available streamflow or as changes to diversions occur. New storage projects that alter the timing of streamflows or shortages may also be evaluated.

Model Development and Structure

The model was developed using Microsoft® Excel 97. The workbooks contain macros written in the Microsoft® Visual Basic for Applications programming language. The primary function of the macros is to facilitate navigation within the workbook.

Each of the Powder/Tongue River sub-basin models is a workbook consisting of numerous individual pages (worksheets). Each worksheet is a component of the model and completes a specific task required for execution of the model. There are five basic types of worksheets:

A more detailed description of the development of the spreadsheet models is provided in the .Spreadsheet Model Development and Calibration. technical memorandum.

Determination of Available Surface Water

The estimated amount of water flowing through each of the various model reaches, as previously described, provides the primary basis for determining how much water is physically available for future development. Reaches are typically defined by gages or confluences, and represent tributary basins or subsections of the mainstem. A Reach Outflow worksheet is provided in each model, summarizing the monthly flow at the downstream end of each reach. The information provided in these summaries is used for this analysis.

While simulated flow at the reach terminus indicates the estimated amount of water physically present, it does not fully reflect availability. Downstream demands relying on the water physically available at any given location must first be accounted for. These downstream demands fall into three general categories:

  1. Existing irrigation, or municipal diversions
  2. Instream flow constraints
  3. Compact constraints
Available Flow in Excess of Existing Diversion Demands

To determine how much of the physical supply is actually available in excess of existing demands, .available flow. at each reach terminus is defined as the minimum of the physically available flow at that point, and the .available flow. at all downstream reaches. Thus available flow must be defined first at the most downstream point, with upstream availability calculated in stream order. These calculations are made on a monthly basis, and annual water availability is computed as the sum of monthly values.

Instream Flow Constraints

Instream flow rights exert a demand on the river but do not affect physical supply, because the water is not removed from the stream. Sufficient flow must be bypassed through upstream reaches to satisfy downstream instream flow requirements. The available flow for reaches located upstream from permitted instream flows are determined as the minimum of physical flow at that point, and available flow in excess of existing diversion demands less the instream flow requirement at the downstream reach.

With only one exception, all of the six instream flow rights within the planning area are located above the most upstream reach explicitly simulated in the model. The available flow for future development reported herein, therefore, is downstream from most of these instream flow constraints. The exception is a 9.86-mile long reach of the Middle Fork Powder River with a 1987 priority instream flow requirement of 12 to 25 cfs. The available flow in Reach 2 of the Powder River sub-basin was calculated taking this instream flow demand into consideration.

The reach by reach results of the monthly available flow determination, accounting for the instream flow constraints, are provided in Tables III-15 through III-32 for each of the six sub- basins and for each of the three hydrologic conditions (wet, normal, and dry years). The total annual available flow is summarized in Table III-14 for each sub-basin and hydrologic condition. The locations of these available flows are also shown graphically on Figures III-15 through III- 20 for the limiting dry year conditions.

Table III-14
Total Annual Available Flow
Subbasin Hydrologic Condition
Wet Years Normal Years Dry Years
Little Bighorn River 152,000 113,000 81,000
Tongue River 473,000 326,000 218,000
Clear Creek 213,000 124,000 80,000
Crazy Woman Creek 69,000 32,000 16,000
Powder River 547,000 324,000 194,000
Little Powder River 48,000 12,000 3,000

Table III-15
Available Flow for Little Bighorn Basin (Acre-Feet) -
Wet Year Hydrologic Conditions
'
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 East Pass Cr below USGS gage 06289800 549 484 684 1,035 3,727 4,598 1,411 517 721 710 600 210 15,555
2 East Pass Cr below USGS gage 06289820 568 496 690 1,035 3,741 4,636 1,458 573 788 760 638 549 15,931
3 Elkhorn Creek below USGS gage 06288975 89 81 92 136 711 1,115 315 147 150 118 102 95 3,153
4Red Canyon Creek below USGS gage 06289100 46 37 66 346 1,001 421 105 48 44 60 52 42 2,268

Table III-16
Available Flow for Little Bighorn Basin (Acre-Feet) -
Normal Year Hydrologic Conditions
'
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 East Pass Cr below USGS gage 06289800 528 542 635 982 2,882 2,855 883 494 512 596 562 544 12,016
2 East Pass Cr below USGS gage 06289820 549 556 643 988 2,906 2,902 937 556 589 654 605 575 12,461
3 Elkhorn Creek below USGS gage 06288975 86 75 88 137 464 592 174 124 114 116 101 92 2,164
4Red Canyon Creek below USGS gage 06289100 29 24 43 213 544 238 61 29 28 40 35 28 1,313

Table III-17
Available Flow for Little Bighorn Basin (Acre-Feet) -
Dry Year Hydrologic Conditions
'
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 East Pass Cr below USGS gage 06289800 506 458 592 790 1,407 1,317 673 398 475 620 578 551 8,364
2 East Pass Cr below USGS gage 06289820 527 472 600 804 1,455 1,387 743 470 565 688 628 586 8,926
3 Elkhorn Creek below USGS gage 06288975 81 70 83 141 317 246 133 109 91 104 97 90 1,562
4Red Canyon Creek below USGS gage 06289100 23 17 24 125 258 101 32 20 23 29 28 22 702

Table III-18
Available Flow for Tongue River Basin (Acre-Feet) -
Wet Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Tongue River above Little Tongue River 3,493 3,099 4,101 5,652 34,863 69,125 25,201 8,354 5,454 5,369 4,132 3,715 172,557
2 Little Tongue River 132 109 151 334 4,235 7,620 1,320 56 0 238 164 143 14,502
3 Tongue River above Wolf Creek 3,826 3,343 4,325 5,986 39,098 76,744 26,521 8,410 5,454 6,123 4,689 4,156 188,675
4 Wolf Creek 507 395 456 736 7,343 12,285 2,000 0 10 1,014 765 630 26,141
5 Tongue River above Goose Creek 4,443 3,889 4,866 6,723 46,441 89,029 28,521 8,410 5,464 7,481 5,891 4,915 216,074
6 Big Goose Creek above Rapid Creek 904 1,286 2,907 3,434 20,500 45,977 15,058 2,911 3,258 1,898 1,341 1,169 100,643
7 Rapid Creek 69 73 140 48 622 1,269 914 0 0 113 91 79 3,418
8 Big Goose Creek above Beaver Creek 1,124 1,461 3,103 3,483 21,123 47,246 15,972 2,911 3,258 2,218 1,725 1,471 105,095
9 Beaver Creek 93 60 52 73 492 715 180 88 71 220 186 142 2,373
10 Big Goose Creek above Little Goose Creek 1,400 1,633 3,209 3,561 21,649 48,030 16,152 2,998 3,329 2,438 2,037 1,704 108,141
11 Little Goose Creek 2,224 2,093 3,152 3,297 17,881 21,368 4,782 1,962 3,047 3,462 2,966 2,478 68,712
12 Goose Creek above Soldier Creek 3,931 3,983 6,542 7,735 41,796 70,136 20,934 4,960 6,376 5,901 5,002 4,182 181,477
13 Soldier Creek 975 690 596 535 1,360 1,604 490 436 579 1,013 928 806 10,013
14 Goose Creek below Soldier Creek 4,906 4,767 7,306 8,477 44,499 75,198 22,253 5,480 7,142 6,914 6,062 4,988 197,990
15 Goose Creek above Tongue River 4,906 5,011 9,233 10,526 51,560 78,270 24,483 5,480 7,566 6,914 6,182 4,988 215,479
16 Tongue River above Prairie Dog Creek 9,349 8,940 14,121 17,249 98,002 167,299 53,003 14,251 13,030 14,395 12,185 9,903 431,727
17 Prairie Dog Creek above USGS gage 06306250 991 1,816 5,423 3,027 8,112 3,531 2,223 2,239 2,303 2,132 1,815 1,449 35,063
18 Prairie Dog Creek above Tongue River 991 1,909 6,853 3,768 9,419 3,687 2,475 2,476 2,513 2,132 1,851 1,449 39,522
19 Tongue River above State Line 10,340 10,940 21,038 21,378 108,313 171,233 55,478 16,727 15,543 16,527 14,165 11,352 473,035

Table III-19
Available Flow for Tongue River Basin (Acre-Feet) -
Normal Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Tongue River above Little Tongue River 4,097 3,785 4,287 6,797 31,196 40,228 14,135 5,834 4,768 5,298 4,087 3,729 128,239
2 Little Tongue River 153 146 167 389 2,860 3,579 524 0 0 224 162 140 8,344
3 Tongue River above Wolf Creek 4,440 4,054 4,518 7,186 34,055 43,806 14,659 5,834 4,768 6,046 4,654 4,166 138,186
4 Wolf Creek 549 469 459 779 4,696 6,156 603 0 66 1,000 763 615 16,155
5 Tongue River above Goose Creek 5,203 4,663 5,051 7,965 38,751 49,962 15,262 5,834 5,061 7,484 5,868 5,113 156,217
6 Big Goose Creek above Rapid Creek 1,167 1,996 2,534 3,506 12,104 24,197 4,773 2,016 1,844 1,864 1,365 1,191 58,558
7 Rapid Creek 71 105 122 0 0 1,735 104 0 0 99 90 76 2,402
8 Big Goose Creek above Beaver Creek 1,383 2,196 2,705 3,506 12,104 25,933 4,877 2,016 2,077 2,219 1,758 1,491 62,264
9 Beaver Creek 98 71 51 62 292 386 117 74 132 247 207 154 1,890
10 Big Goose Creek above Little Goose Creek 1,663 2,378 2,808 3,568 12,431 26,426 5,152 2,090 2,604 2,466 2,129 1,877 65,590
11 Little Goose Creek 2,131 2,441 2,613 3,370 9,008 9,619 1,226 1,802 2,081 3,388 2,962 2,569 43,210
12 Goose Creek above Soldier Creek 3,957 4,959 5,472 8,222 22,407 36,483 8,086 3,892 5,273 5,854 5,091 4,446 114,140
13 Soldier Creek 679 548 475 507 905 901 600 348 774 960 884 786 8,366
14 Goose Creek below Soldier Creek 4,729 5,627 6,080 8,953 24,129 38,824 8,919 4,325 6,185 6,832 6,107 5,341 126,069
15 Goose Creek above Tongue River 5,712 7,430 8,224 10,623 24,604 39,850 9,845 4,327 6,513 6,832 6,107 5,341 135,408
16 Tongue River above Prairie Dog Creek 10,970 12,129 13,293 18,588 63,356 89,813 25,107 10,161 11,574 14,317 12,091 10,471 291,870
17 Prairie Dog Creek above USGS gage 06306250 1,174 2,419 4,913 2,968 2,928 2,289 1,335 1,630 2,521 2,471 1,977 1,644 28,268
18 Prairie Dog Creek above Tongue River 1,418 3,193 6,645 3,535 3,000 2,364 1,511 1,713 2,727 2,471 1,977 1,644 32,198
19 Tongue River above State Line 12,437 15,372 19,950 22,686 66,751 92,276 27,317 11,874 14,461 16,788 14,097 12,116 326,123

Table III-20
Available Flow for Tongue River Basin (Acre-Feet) -
Dry Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Tongue River above Little Tongue River 3,004 2,653 3,226 7,848 31,008 19,377 5,581 3,057 2,722 4,730 3,749 3,259 90,215
2 Little Tongue River 107 90 113 353 2,579 1,392 0 0 0 193 143 122 5,092
3 Tongue River above Wolf Creek 3,111 2,773 3,408 8,201 33,587 20,768 5,581 3,057 2,722 5,505 4,368 3,381 96,462
4 Wolf Creek 394 313 348 606 4,271 2,173 0 0 26 969 747 503 10,350
5 Tongue River above Goose Creek 3,505 3,086 3,840 8,807 37,857 22,941 5,581 3,057 3,017 6,474 5,283 3,884 107,333
6 Big Goose Creek above Rapid Creek 1,019 1,132 2,622 2,573 13,498 9,327 84 0 0 1,631 1,265 1,154 34,305
7 Rapid Creek 64 64 123 0 0 584 0 0 0 74 87 76 1,073
8 Big Goose Creek above Beaver Creek 1,216 1,276 2,789 2,573 13,498 9,911 97 102 202 1,773 1,656 1,281 36,374
9 Beaver Creek 52 29 37 0 282 192 48 12 0 174 175 100 1,101
10 Big Goose Creek above Little Goose Creek 1,312 1,341 2,868 2,573 13,779 10,333 373 376 526 1,947 1,831 1,381 38,641
11 Little Goose Creek 1,661 1,581 2,723 1,357 6,347 1,038 887 932 1,042 2,661 2,468 1,789 24,485
12 Goose Creek above Soldier Creek 2,973 2,922 5,636 6,367 20,126 15,795 2,242 1,502 2,100 4,607 4,299 3,170 71,738
13 Soldier Creek 602 514 501 598 821 810 671 379 649 909 861 638 7,952
14 Goose Creek below Soldier Creek 3,575 3,436 6,277 7,133 21,677 17,157 2,912 1,880 2,749 5,517 5,160 3,808 81,280
15 Goose Creek above Tongue River 3,575 3,436 7,041 7,615 21,726 17,598 2,912 1,880 2,749 5,517 5,160 3,808 83,018
16 Tongue River above Prairie Dog Creek 7,080 6,522 10,881 16,422 59,584 40,540 8,494 4,938 5,765 11,990 10,443 7,692 190,351
17 Prairie Dog Creek above USGS gage 06306250 938 1,975 4,793 2,043 1,678 1,279 878 1,496 1,928 2,055 1,695 1,196 21,953
18 Prairie Dog Creek above Tongue River 938 1,975 5,366 2,208 1,696 1,335 878 1,496 1,928 2,055 1,695 1,196 22,765
19 Tongue River above State Line 8,018 8,497 16,247 19,902 61,280 43,982 10,638 6,433 7,775 14,045 12,138 8,888 217,843

Table III-21
Available Flow for Clear Creek Basin (Acre-Feet) -
Wet Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 North Piney Creek 225 215 333 1,155 10,872 16,085 2,167 415 182 556 400 225 32,862
2 South Piney Creek 779 712 947 1,393 6,134 20,952 8,806 2,959 1,158 1,702 1,158 889 47,589
3 Piney Creek below North & South Piney Creeks 1,004 927 1,280 2,549 17,006 37,038 10,973 3,374 1,340 2,259 1,558 1,444 80,451
4 Piney Creek below USGS gage 06323000 1,004 927 1,280 2,549 17,006 37,038 10,973 3,374 1,762 2,259 1,558 1,444 80,873
5 Piney Creek below Lake DeSmet Intake Tunnel 1,655 1,142 2,336 3,204 17,006 37,038 12,311 4,386 1,852 2,655 2,529 1,150 87,264
6 Little Piney Creek above SEO gage 642 833 1,030 904 1,426 2,311 1,336 722 707 925 830 582 12,246
7 Little Piney Creek above Piney Creek 1,058 960 1,786 904 1,426 2,311 1,434 939 743 1,087 1,346 585 14,578
8 Piney Creek below Little Piney Creek 2,712 2,191 4,172 4,108 18,431 39,348 13,745 5,325 2,595 3,742 4,072 1,736 102,179
10 Piney Creek below Box Elder Creek 2,712 2,221 4,190 4,203 18,431 39,348 13,745 5,325 2,595 3,742 4,072 1,736 102,322
11 Piney Creek above Clear Creek 2,712 3,224 5,689 5,198 18,431 39,348 13,745 5,325 2,595 3,742 4,072 1,736 105,819
12 Rock Creek 524 815 1,408 1,274 8,173 12,220 2,799 769 615 1,008 863 330 30,798
13 Johnson Creek 48 50 83 38 326 456 0 0 0 122 134 45 1,304
14 Rock Creek below Johnson Creek 573 865 1,491 1,451 9,102 12,676 2,799 769 615 1,130 997 376 32,844
15 Rock Creek above Clear Creek 573 865 1,491 1,451 9,102 12,676 2,799 769 615 1,130 997 376 32,844
16 French Creek 73 53 57 55 1,135 1,981 1,672 182 0 118 141 55 5,523
17 Clear Creek above City of Buffalo 1,046 1,423 1,982 2,929 15,386 21,221 8,254 1,672 1,168 2,226 1,945 756 60,007
18 Clear Creek above French Creek 1,046 1,423 1,982 2,929 15,449 21,221 8,254 1,672 1,168 2,226 1,945 756 60,070
19 Clear Creek above Rock Creek 1,119 1,476 2,039 2,984 16,584 23,202 9,926 1,854 1,398 2,344 2,086 811 65,823
20 Clear Creek below Rock Creek 1,691 2,341 3,530 4,435 25,686 35,878 12,725 2,624 2,014 3,474 3,084 1,186 98,668
21 Clear Creek above Healy Reservoir 1,691 2,658 3,530 4,435 25,686 35,878 12,725 2,624 2,014 4,444 3,084 1,186 99,955
23 Clear Creek above Piney Creek 1,691 3,911 4,824 5,374 25,686 35,878 12,725 2,624 2,014 4,444 3,128 1,186 103,486
24 Clear Creek above Double Crossing 4,404 7,135 10,514 10,678 44,118 75,227 26,470 7,949 4,609 8,186 7,200 2,922 209,410
25 Clear Creek below Double Crossing 4,404 7,135 10,514 10,929 44,118 75,227 26,470 7,949 4,609 8,186 7,200 2,922 209,661
26 Clear Creek above USGS gage 06324000 4,404 7,135 10,514 10,929 44,118 75,227 26,470 7,949 4,609 8,186 7,200 2,922 209,661
27 Clear Creek above Powder River 4,440 7,568 11,728 10,929 44,118 75,227 27,431 8,047 4,609 8,186 7,345 2,922 212,547
28 Powder River above Clear Creek 7,589 11,731 30,400 20,315 102,759 87,040 26,344 8,276 4,655 16,458 11,810 6,250 333,625
29 Powder River above State Line 12,118 19,360 42,163 31,243 146,877 162,267 53,775 16,330 9,263 24,643 19,325 9,172 546,537

Table III-22
Available Flow for Clear Creek Basin (Acre-Feet) -
Normal Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 North Piney Creek 171 173 282 891 5,910 5,342 714 217 197 427 316 188 14,829
2 South Piney Creek 472 422 578 788 3,263 10,730 3,104 1,680 1,235 1,036 741 525 24,574
3 Piney Creek below North & South Piney Creeks 642 595 861 1,678 9,173 16,073 3,818 1,897 1,432 1,463 1,057 713 39,403
4 Piney Creek below USGS gage 06323000 642 595 861 1,678 9,173 16,073 3,818 2,047 1,432 1,463 1,057 713 39,552
5 Piney Creek below Lake DeSmet Intake Tunnel 914 656 1,389 2,465 9,915 16,073 3,818 2,631 1,858 1,463 1,668 1,036 43,887
6 Little Piney Creek above SEO gage 549 707 950 954 904 828 652 584 718 744 722 580 8,892
7 Little Piney Creek above Piney Creek 781 781 1,533 1,339 904 828 652 750 931 744 1,139 842 11,224
8 Piney Creek below Little Piney Creek 1,823 1,524 2,971 3,804 10,819 16,901 4,470 3,504 3,595 3,045 3,091 2,080 57,629
10 Piney Creek below Box Elder Creek 1,851 1,543 2,979 3,926 10,819 16,901 4,470 3,504 3,595 3,045 3,150 2,126 57,910
11 Piney Creek above Clear Creek 2,483 2,956 5,419 4,932 10,819 16,901 4,470 3,504 3,595 3,823 4,018 2,659 65,579
12 Rock Creek 283 441 1,061 766 3,283 4,820 954 479 439 545 417 297 13,787
13 Johnson Creek 28 32 62 0 0 0 0 0 0 86 74 42 324
14 Rock Creek below Johnson Creek 311 474 1,123 1,203 3,283 4,820 954 479 514 631 491 339 14,623
15 Rock Creek above Clear Creek 311 474 1,123 1,203 3,283 4,820 954 479 514 631 491 339 14,623
16 French Creek 63 45 49 67 552 1,022 619 0 0 170 125 94 2,805
17 Clear Creek above City of Buffalo 457 526 1,090 2,159 6,836 11,079 3,063 1,339 1,501 1,115 757 563 30,483
18 Clear Creek above French Creek 457 526 1,090 2,261 6,836 11,079 3,063 1,339 1,501 1,115 757 563 30,586
19 Clear Creek above Rock Creek 520 571 1,138 2,329 7,388 12,101 3,682 1,339 1,614 1,285 882 656 33,504
20 Clear Creek below Rock Creek 831 1,044 2,262 3,532 10,670 16,921 4,636 1,818 2,127 1,916 1,373 996 48,127
21 Clear Creek above Healy Reservoir 831 1,044 2,262 3,532 10,670 16,921 4,636 1,818 2,127 1,916 1,373 996 48,127
23 Clear Creek above Piney Creek 1,197 2,062 4,148 4,253 10,670 16,921 4,636 1,818 2,127 2,638 1,933 1,364 53,768
24 Clear Creek above Double Crossing 3,680 5,128 9,624 9,332 21,489 33,822 9,106 5,322 5,723 6,461 5,951 4,023 119,660
25 Clear Creek below Double Crossing 3,680 5,673 9,946 9,798 21,489 33,822 9,106 5,322 5,723 6,461 5,951 4,023 120,994
26 Clear Creek above USGS gage 06324000 3,680 5,852 10,041 9,798 21,489 33,822 9,106 5,322 6,083 6,461 5,951 4,023 121,630
27 Clear Creek above Powder River 3,734 6,701 10,850 9,798 21,489 33,822 9,635 5,322 6,083 6,523 5,951 4,023 123,932
28 Powder River above Clear Creek 6,519 13,902 25,996 22,124 40,971 37,368 14,105 6,557 6,452 9,968 9,003 6,715 199,680
29 Powder River above State Line 10,319 20,648 36,869 31,922 62,461 71,190 23,837 11,879 12,535 16,672 14,954 10,739 324,023

Table III-23
Available Flow for Clear Creek Basin (Acre-Feet) -
Dry Year Hydrologic Conditions

Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 North Piney Creek 102 96 127 1,422 3,684 1,116 263 77 61 294 179 116 7,536
2 South Piney Creek 284 260 331 758 2,029 4,195 1,770 707 436 680 373 306 12,129
3 Piney Creek below North & South Piney Creeks 387 356 458 2,180 5,713 5,311 2,033 784 497 974 552 422 19,666
4 Piney Creek below USGS gage 06323000 387 356 458 2,180 5,713 5,311 2,871 1,073 1,094 974 552 422 21,391
5 Piney Creek below Lake DeSmet Intake Tunnel 1,168 464 548 2,517 5,713 5,311 3,138 1,668 1,621 974 1,305 1,262 25,688
6 Little Piney Creek above SEO gage 627 589 941 809 263 534 660 538 586 766 760 636 7,708
7 Little Piney Creek above Piney Creek 1,894 768 1,128 934 263 534 721 836 868 766 1,799 1,901 12,411
8 Piney Creek below Little Piney Creek 3,181 1,307 1,717 3,451 5,976 5,845 3,859 3,013 2,522 3,235 3,416 3,176 40,699
10 Piney Creek below Box Elder Creek 3,181 1,307 1,717 3,657 5,976 5,845 3,859 3,013 2,522 3,235 3,416 3,176 40,905
11 Piney Creek above Clear Creek 3,670 1,828 2,931 3,810 5,976 5,845 3,859 3,013 2,522 4,247 4,579 3,176 45,456
12 Rock Creek 315 485 904 173 2,269 617 0 0 0 409 379 342 5,890
13 Johnson Creek 28 30 47 0 0 0 0 0 0 59 60 39 263
14 Rock Creek below Johnson Creek 343 515 951 905 2,269 617 146 97 111 467 439 381 7,241
15 Rock Creek above Clear Creek 343 515 951 905 2,269 617 146 97 111 467 439 381 7,241
16 French Creek 66 47 44 0 410 161 240 0 0 180 138 90 1,376
17 Clear Creek above City of Buffalo 643 919 1,106 2,403 4,118 2,681 530 339 322 1,000 871 776 15,707
18 Clear Creek above French Creek 643 919 1,106 2,403 4,118 2,681 530 339 322 1,000 871 776 15,707
19 Clear Creek above Rock Creek 709 966 1,150 2,403 4,528 2,841 769 339 322 1,180 1,009 867 17,082
20 Clear Creek below Rock Creek 1,052 1,480 2,101 3,308 6,797 3,458 915 436 433 1,647 1,448 1,248 24,323
21 Clear Creek above Healy Reservoir 1,052 1,480 2,101 3,308 6,797 3,458 915 436 433 1,647 1,448 1,248 24,323
23 Clear Creek above Piney Creek 1,294 2,120 3,625 3,308 6,797 3,458 915 436 433 2,440 2,165 1,287 28,278
24 Clear Creek above Double Crossing 4,964 3,949 6,584 7,413 12,773 9,303 4,774 3,449 2,955 6,687 6,744 4,462 74,056
25 Clear Creek below Double Crossing 4,964 3,949 8,902 8,139 12,773 9,303 4,774 3,449 2,955 6,687 6,744 4,462 77,102
26 Clear Creek above USGS gage 06324000 4,964 3,949 8,956 8,554 12,773 9,400 4,774 3,449 3,482 6,687 6,744 4,462 78,194
27 Clear Creek above Powder River 4,964 3,949 9,016 8,554 12,773 10,282 4,774 3,698 3,482 7,125 7,038 4,462 80,118
28 Powder River above Clear Creek 6,602 9,561 18,787 13,486 20,647 10,304 5,594 3,013 2,122 8,145 8,998 5,803 113,062
29 Powder River above State Line 11,567 13,510 27,822 22,040 33,420 20,735 10,368 6,822 5,603 15,447 16,172 10,265 193,770

Table III-24
Available Flow for Crazy Woman Creek Basin (Acre-Feet) -
Wet Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Kelly Creek 10 8 8 98 679 731 180 95 20 17 13 11 1,870
2 Little North Fork Crazy Woman Creek 22 18 19 214 1,499 1,602 371 182 36 38 29 25 4,055
3 North Fork Crazy Woman Creek 79 57 69 761 7,592 10,292 1,619 714 143 141 98 87 21,650
4 N Fk Crazy Woman Cr bel. Kelly & Little N Fk 111 84 96 1,073 9,769 12,626 2,170 990 199 195 139 124 27,575
5 Muddy Creek 17 14 16 198 1,347 1,398 318 150 19 27 20 18 3,541
6 Billy Creek 10 9 12 137 443 401 93 77 16 12 10 10 1,230
7 N Fk Crazy Woman Cr bel. Muddy & Billy Cr 137 107 123 1,408 11,559 14,425 2,581 1,217 234 234 169 152 32,346
8 Middle Fork Crazy Woman Creek 75 60 82 885 5,421 6,630 1,386 865 177 108 79 75 15,842
9 Crazy Woman Cr above S Fk Crazy Woman Cr 213 167 205 2,293 16,980 21,055 3,967 2,082 411 342 248 227 48,189
10 Crazy Woman Cr above Trabing Bridge 213 167 205 2,705 16,980 21,055 3,967 2,082 411 342 248 227 48,600
11 Crazy Woman Cr above Upper Station 792 1,494 2,802 3,472 20,742 21,055 3,967 2,082 411 2,439 1,522 720 61,498

Table III-25
Available Flow for Crazy Woman Creek Basin (Acre-Feet) -
Normal Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Kelly Creek 9 7 8 64 279 283 86 37 20 17 11 11 831
2 Little North Fork Crazy Woman Creek 21 15 17 136 598 587 160 65 32 39 26 25 1,720
3 North Fork Crazy Woman Creek 67 49 58 538 3,544 3,251 780 279 133 128 87 82 8,995
4 N Fk Crazy Woman Cr bel. Kelly & Little N Fk 97 71 83 739 4,421 4,120 1,025 380 185 184 124 117 11,546
5 Muddy Creek 16 12 14 125 511 470 87 26 0 28 18 18 1,325
6 Billy Creek 9 8 10 74 179 143 39 39 8 12 9 9 539
7 N Fk Crazy Woman Cr bel. Muddy & Billy Cr 122 91 107 937 5,111 4,734 1,151 445 193 224 151 144 13,410
8 Middle Fork Crazy Woman Creek 64 53 75 652 2,684 2,366 667 344 90 100 70 70 7,235
9 Crazy Woman Cr above S Fk Crazy Woman Cr 186 144 182 1,589 7,795 7,100 1,818 789 283 324 221 215 20,645
10 Crazy Woman Cr above Trabing Bridge 186 144 182 1,589 7,795 7,100 2,075 959 812 324 221 215 21,602
11 Crazy Woman Cr above Upper Station 656 1,679 2,626 3,560 7,795 7,100 2,075 1,016 812 1,321 1,184 786 30,610

Table III-26
Available Flow for Crazy Woman Creek Basin (Acre-Feet) -
Dry Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Kelly Creek 10 7 8 39 57 54 0 0 0 17 11 12 215
2 Little North Fork Crazy Woman Creek 24 16 19 79 121 99 0 0 0 38 24 27 446
3 North Fork Crazy Woman Creek 71 47 58 365 620 511 0 0 0 124 74 79 1,949
4 N Fk Crazy Woman Cr bel. Kelly & Little N Fk 105 71 84 483 798 663 0 0 0 179 109 118 2,610
5 Muddy Creek 19 14 17 68 104 33 0 0 0 30 19 20 325
6 Billy Creek 11 9 12 39 38 4 0 0 0 13 9 10 145
7 N Fk Crazy Woman Cr bel. Muddy & Billy Cr 135 94 114 590 941 700 0 0 0 222 137 148 3,080
8 Middle Fork Crazy Woman Creek 76 59 79 423 501 453 0 0 0 108 67 73 1,839
9 Crazy Woman Cr above S Fk Crazy Woman Cr 210 153 193 1,013 1,442 1,153 0 0 0 330 204 221 4,918
10 Crazy Woman Cr above Trabing Bridge 210 153 193 1,013 1,442 1,788 532 168 123 330 204 221 6,377
11 Crazy Woman Cr above Upper Station 836 1,031 1,904 2,113 3,540 2,361 532 168 123 1,022 1,135 754 15,520

Table III-27
Available Flow for Powder River Basin (Acre-Feet) -
Wet Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Buffalo Creek 195 181 273 618 3,342 1,414 0 0 0 202 255 208 6,687
2 Middle Fork Powder River1 51 85 362 1,601 11,430 6,449 418 268 600 117 242 85 21,707
3 Middle Fork Powder River below Buffalo Creek 913 974 1,395 2,874 14,771 7,863 418 268 600 1,221 1,403 819 33,518
4 Beaver Creek 1,063 1,113 1,311 1,181 2,657 1,489 258 263 641 1,022 1,079 889 12,967
5 Beaver Creek below Blue Creek 1,063 1,187 1,355 1,181 2,657 1,489 258 263 641 1,212 1,283 889 13,479
6 Middle Fork Powder River below Beaver Creek 1,975 2,273 2,817 4,055 17,429 9,352 676 531 1,241 2,432 2,927 1,708 47,417
7 Middle Fk Powder River above Red Fk Powder 1,975 2,466 2,997 4,055 17,429 9,352 676 531 1,241 2,432 2,928 1,708 47,791
8 Red Fork Powder River 1,940 2,358 2,799 3,040 12,699 6,977 536 404 926 2,465 2,883 1,709 38,738
9 Middle Fk Powder River above N Fk Powder 3,915 4,824 5,796 7,095 30,128 16,330 1,212 935 2,167 4,898 6,001 3,418 86,718
10 North Fork Powder River 1,145 1,291 1,288 716 5,136 4,353 98 48 156 1,698 1,822 1,004 18,757
11 Powder River below N & Middle Fks Powder 5,060 6,115 7,085 7,811 35,264 20,683 1,310 983 2,323 6,596 7,823 4,422 105,474
12 Powder River above South Fork Powder 5,060 6,115 7,805 7,811 42,733 37,477 3,051 983 2,323 9,932 7,823 4,422 134,816
13 South Fork Powder River 229 1,369 8,011 6,589 17,715 5,530 1,989 2,067 15 418 370 123 44,427
14 Powder River above Salt Creek 5,290 7,484 15,096 14,400 60,729 43,564 5,694 3,051 2,642 10,350 8,193 4,544 181,036
15 Salt Creek 1,452 2,090 4,095 2,469 12,546 7,727 9,183 1,613 1,638 3,694 1,879 993 49,377
16 Powder River below Salt Creek 6,741 9,573 19,191 16,870 73,310 51,299 14,882 4,663 4,280 14,044 10,072 5,537 230,461
17 Powder River above Crazy Woman Creek 6,741 9,573 23,790 16,870 80,197 61,924 20,283 5,915 4,280 14,044 10,072 5,537 259,255
18 Crazy Woman Creek above Powder River 785 1,487 3,459 3,445 22,562 25,117 5,101 2,206 375 2,414 1,505 712 69,167
19 Powder River below Crazy Woman Creek 7,527 11,060 27,253 20,315 102,759 87,040 25,422 8,175 4,655 16,458 11,577 6,250 328,489

Note: 1 Constrained by Instream Flow Rights of 12 cfs (July 1 - March 31) and 25 cfs (April 1 - June 30).

Table III-28
Available Flow for Powder River Basin (Acre-Feet) -
Normal Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Buffalo Creek 202 190 267 694 2,090 100 0 0 0 236 231 214 4,226
2 Middle Fork Powder River1 0 0 0 280 6,819 2,957 0 0 0 0 0 0 10,056
3 Middle Fork Powder River below Buffalo Creek 745 968 1,324 3,152 10,841 6,385 399 261 570 881 1,085 821 27,431
4 Beaver Creek 964 1,244 1,384 1,175 1,729 1,474 233 240 553 956 1,228 988 12,166
5 Beaver Creek below Blue Creek 964 1,290 1,402 1,175 1,729 1,566 233 240 553 956 1,228 988 12,322
6 Middle Fork Powder River below Beaver Creek 1,709 2,258 2,727 4,327 12,569 8,716 632 500 1,123 1,837 2,312 1,809 40,519
7 Middle Fk Powder River above Red Fk Powder 1,709 2,525 3,423 4,327 12,569 8,716 632 500 1,123 1,837 2,312 1,809 41,483
8 Red Fork Powder River 1,658 2,396 3,155 3,347 7,408 4,935 393 310 647 1,790 2,277 1,788 30,105
9 Middle Fk Powder River above N Fk Powder 3,367 4,922 6,579 7,674 19,977 13,651 1,025 811 1,770 3,627 4,589 3,597 71,587
10 North Fork Powder River 971 1,272 1,451 997 2,629 1,918 0 0 5 1,284 1,500 1,119 13,145
11 Powder River below N & Middle Fks Powder 4,338 6,193 8,029 8,671 22,606 16,087 1,025 811 1,775 4,911 6,089 4,716 85,251
12 Powder River above South Fork Powder 4,338 6,653 8,029 9,371 22,606 17,055 1,908 821 2,730 5,790 6,089 4,716 90,107
13 South Fork Powder River 132 1,287 7,025 5,987 6,835 2,093 1,132 1,699 17 188 213 112 26,720
14 Powder River above Salt Creek 4,470 7,940 15,054 15,358 29,441 19,403 3,580 3,010 3,353 6,189 6,302 4,828 118,929
15 Salt Creek 1,306 2,532 3,882 3,239 3,750 4,823 5,081 1,705 2,350 2,399 1,540 1,114 33,722
16 Powder River below Salt Creek 5,776 10,472 18,936 18,597 33,192 24,225 8,661 4,715 5,703 8,588 7,842 5,943 152,650
17 Powder River above Crazy Woman Creek 5,776 10,472 21,140 18,597 33,192 29,159 11,002 5,572 5,732 8,588 7,842 5,943 163,014
18 Crazy Woman Creek above Powder River 648 1,669 2,919 3,526 7,779 8,209 2,328 985 720 1,286 1,162 773 32,004
19 Powder River below Crazy Woman Creek 6,424 12,141 24,059 22,124 40,971 37,368 13,330 6,557 6,452 9,874 9,003 6,715 195,018

Note: 1 Constrained by Instream Flow Rights of 12 cfs (July 1 - March 31) and 25 cfs (April 1 - June 30).

Table III-29
Available Flow for Powder River Basin (Acre-Feet) -
Dry Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Buffalo Creek 187 169 214 298 909 0 0 0 0 167 206 197 2,347
2 Middle Fork Powder River1 0 0 0 425 3,840 0 0 0 0 0 0 0 4,265
3 Middle Fork Powder River below Buffalo Creek 633 799 1,072 2,985 6,625 2,576 240 219 360 586 829 597 17,521
4 Beaver Creek 921 1,164 1,365 961 943 830 199 248 405 820 1,096 817 9,767
5 Beaver Creek below Blue Creek 921 1,164 1,399 961 943 846 199 248 405 820 1,096 817 9,817
6 Middle Fork Powder River below Beaver Creek 1,553 1,964 2,471 3,946 7,568 3,421 438 467 765 1,407 1,925 1,414 27,338
7 Middle Fk Powder River above Red Fk Powder 1,553 1,964 2,651 3,946 7,568 3,421 438 467 765 1,407 1,925 1,414 27,518
8 Red Fork Powder River 1,544 1,892 2,451 2,332 3,262 1,603 205 268 358 1,487 1,903 1,435 18,740
9 Middle Fk Powder River above N Fk Powder 3,097 3,856 5,101 6,278 10,831 5,024 643 735 1,123 2,894 3,828 2,849 46,258
10 North Fork Powder River 919 1,089 1,278 385 1,069 0 0 0 0 1,090 1,288 917 8,036
11 Powder River below N & Middle Fks Powder 4,016 4,945 6,379 6,662 11,900 5,024 643 735 1,123 3,984 5,116 3,766 54,294
12 Powder River above South Fork Powder 4,016 4,945 6,379 6,662 11,900 5,024 900 735 1,123 4,159 5,229 3,766 54,840
13 South Fork Powder River 94 1,074 3,574 2,698 3,480 564 377 864 6 90 121 84 13,026
14 Powder River above Salt Creek 4,110 6,019 9,953 9,360 15,380 5,588 1,886 1,599 1,129 4,674 5,648 3,850 69,196
15 Salt Creek 1,660 2,515 2,780 2,108 1,851 1,044 3,197 1,054 924 1,898 1,799 1,206 22,035
16 Powder River below Salt Creek 5,770 8,534 12,733 11,468 17,231 6,632 5,083 2,652 2,053 6,572 7,446 5,056 91,231
17 Powder River above Crazy Woman Creek 5,770 8,534 16,245 11,468 17,231 7,179 5,083 2,652 2,053 6,655 7,507 5,056 95,434
18 Crazy Woman Creek above Powder River 832 1,028 2,418 2,018 3,415 2,241 551 158 69 988 1,114 747 15,539
19 Powder River below Crazy Woman Creek 6,602 9,561 18,663 13,486 20,647 9,420 5,594 2,810 2,122 7,643 8,622 5,803 110,973

Note: 1 Constrained by Instream Flow Rights of 12 cfs (July 1 - March 31) and 25 cfs (April 1 - June 30).

Table III-30
Available Flow for Little Powder River Basin (Acre-Feet) -
Wet Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Little Powder River above USGS gage 06324925 562 7,548 14,241 2,860 9,079 2,733 377 279 53 2,316 180 143 40,372
2 Little Powder River above USGS gage 06324970 1,195 7,548 14,241 2,860 13,237 3,354 1,044 426 226 2,722 485 375 47,714
3 Little Powder River above State Line 1,203 7,553 14,243 2,860 13,237 3,354 1,044 426 226 2,782 520 391 47,838

Table III-31
Available Flow for Little Powder River Basin (Acre-Feet) -
Normal Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Little Powder River above USGS gage 06324925 405 1,109 1,553 1,119 1,970 1,683 625 309 246 283 144 65 9,511
2 Little Powder River above USGS gage 06324970 548 1,493 2,209 1,396 2,190 1,894 674 337 268 450 254 142 11,853
3 Little Powder River above State Line 556 1,497 2,210 1,396 2,190 1,894 674 337 268 504 289 159 11,974

Table III-32
Available Flow for Little Powder River Basin (Acre-Feet) -
Dry Year Hydrologic Conditions
Reach Reach Name Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
1 Little Powder River above USGS gage 06324925 24 319 399 284 474 220 64 74 13 19 26 30 1,946
2 Little Powder River above USGS gage 06324970 60 481 630 344 560 239 105 74 17 41 54 69 2,674
3 Little Powder River above State Line 63 482 630 344 560 239 105 74 43 53 69 75 2,737


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The yield potential of each of these basins is limited by the dry year conditions. Further, the timing of these available flows does not necessarily match the timing of the demand for this water. For example of the 218,000 acre feet of available flow from the Tongue River during a typical dry year, 65 percent of this occurs during the spring runoff months of March through June. Reservoir storage would be required to store this excess flow to satisfy demands throughout the year. The available flow presented in Table III-14 does not include the constraints of the Yellowstone River Compact. This will be discussed in the next section.

Compact Constraints

A determination of the amount of water available to Wyoming for future development is not complete without an evaluation of the constraints imposed by interstate compacts. The Yellowstone River Compact of 1950 governs the allocation of the waters in the Powder River and Tongue River between the States of Montana and Wyoming.

The following is a brief summary of the rules for dividing the waters according to the Yellowstone River Compact:

  1. existing rights as of January 1, 1950 maintain their status quo;
  2. no water may be diverted from the Yellowstone River Basin for use in another River Basin without consent from all states;
  3. existing and future domestic and stock water uses including stock water reservoirs up to a capacity of 20 acre-feet are exempted from provisions of the Compact.

    The unappropriated or unused total divertible flow of each tributary after needs for supplemental supply for existing rights are met, is allocated to Wyoming and Montana on a percentage basis

    Nothing contained in the Compact is to be construed to adversely affect any rights to the use of the waters of the Yellowstone River by or for Indians, Indian tribes, and their reservations.

The methodology used in the current study to evaluate water availability under the Yellowstone River Compact was coordinated through the Wyoming State Engineer.s Office and relies heavily on previous work performed by others on behalf of each of the two States. A more detailed, .from the ground up. evaluation is beyond the scope of the current planning effort. The methodology employed provides estimates of Wyoming.s allocation under each of the three hydrologic conditions (wet, normal, and dry years).

Tongue River

The allocable flows of the Tongue River drainage are to be divided between the two States in accordance with the following percentages per the Yellowstone River Compact:

Wyoming 40%
Montana 60%
The State of Montana sponsored a study in 1990/1991 to determine the amount of water available for storage in the, then proposed, enlargement of Tongue River Reservoir. The State of Wyoming also made a determination of Wyoming.s supplemental water needs for pre-1950 water rights during this same time frame. Information from both sources was utilized in evaluating Wyoming.s share of Tongue River water.

This evaluation is based on the following assumptions:

The range of estimates of remaining allocable flow for the State of Wyoming then centers around what adjustments are to be made to the flows at Miles City to account for unused Tribal and Federal pre-1950 rights and supplemental supplies to pre-1950 Wyoming and Montana State rights. Only the remaining flow, after these adjustments are made, is available for allocation.

In a letter sent to the State of Montana in 1990, Wyoming has claimed a need for 18,702 acre- feet of additional water to supplement the supply of pre-1950 rights. To fully supply these needs, additional reservoir storage with pre-1950 storage rights would likely be required.

The work sponsored by the State of Montana in 1990/1991 makes the assumption that the following four adjustments should be made to the streamflow at Miles City to account for unused pre-1950 rights or supplemental supplies to pre-1950 rights.

  1. Depletions for Northern Cheyenne tribal water rights (31,800 acre-feet),
  2. Winter bypass flow at Tongue River Dam (23,800 acre-feet),
  3. Depletions for the unused 1924 priority USDA irrigation project near Miles City (1,900 acre-feet),
  4. Depletions for supplemental supplies to pre-1950 rights on tributaries to the Tongue River in Montana (9,500 acre-feet).
The winter bypass flow at Tongue River Dam is based on an agreement between the State of Montana and the Tongue River Water Users in the late 1930.s to maintain adequate flow to keep the river free of ice and to allow for stock water use. Because this is not a formal water right, its validity under the Yellowstone River Compact is a matter of legal interpretation. Montana water law does not allow for supplemental water rights and, similar to Wyoming, development of supplemental water supplies would likely require reservoir storage under pre-1950 storage rights in order to be exempt from Compact constraints.

In order to represent the wide range of possible interpretations, two estimates were made of Wyoming.s remaining allocation of Tongue River water per the Yellowstone River Compact (a conservative estimate and a liberal estimate) as summarized in Table III-33. For the liberal estimate, the flow at Miles City is only adjusted to reflect increased depletions for supplemental supply to pre-1950 rights in Wyoming. For the conservative estimate, all of the aforementioned adjustments are included. The actual remaining allocation, to finally be determined at some undefined time in the future, will likely fall somewhere in the middle of this range of estimates.

Table III-33
Wyoming.s Remaining Allocation of Available Flow per Yellowstone River Compact
Hydrologic Condition Tongue River Basin Powder River Basin
Conservative
Estimate
Liberal
Estimate
Wet Years 163,000 189,000 211,500
Normal Years 90,000 117,000 131,100
Dry Years 40,000 67,000 74,300

Additional detail of the determination of available flows is provided in the .Available Surface Water Determination. technical memorandum. For comparative purposes, the Wyoming Water Planning Program estimated Wyoming.s average annual unused and unappropriated portion of the Tongue River to be 96,400 acre-feet for the 1948 through 1968 study period.

Powder River

The allocable flows of the Powder River drainage are to be divided between the two States in accordance with the following percentages per the Yellowstone River Compact:

Wyoming 42%
Montana 58%
Wyoming.s allocation of the Powder River is based on the estimate reported in the previous water plan as directed by the SEO. This estimate has, however, been adjusted to reflect the current study period. The water availability presented in the 1972 water plan was based on the 21-year study period of 1948 through 1968; whereas, the current study utilizes the 30-year period 1970 through 1999. The average annual flow of the Powder River near Locate for the 1948 . 1968 study period is 377,100. The corresponding average for the 1970 . 1999 study period is 424,400. Wyoming.s average annual unused and unappropriated portion of the Powder River, estimated through the earlier study is 120,700 acre-feet. This value is adjusted upwards by 12.5% to 135,800 to reflect the somewhat wetter average annual flow during the current study period. Wyoming.s allocation of the available flows of the Powder River is summarized in Table III-33 for each of the three hydrologic conditions.
B.     Ground Water
A qualitative summary of the ground water resources of the Powder and Tongue River basins of northeastern Wyoming is presented herein. Collectively, these basins and the study area are referred to as the Powder/Tongue River Basin (planning area).

Study Objectives

The first objective of this task was to inventory and catalog the Wyoming State Engineer's Office (SEO) ground water permit database for various categories of ground water uses in the planning area, and incorporate the extracted information into six GIS data themes. This was accomplished through a cooperative effort of personnel of the SEO and Wyoming Water Development Commission (WWDC). GIS data layers prepared from information on file with the SEO as of December 31, 2000 included:

Because of the dynamic nature of CBM development in the planning area, the permitted CBM well data was recollected from the SEO database near the end of this planning effort. The permitted CBM wells are therefore current as of December 31, 2001.

The second objective of this task was to inventory and document existing published data on ground water studies and ground water planning documents for the planning area. All of the planning area is located within the Powder River Structural Basin (PRSB). Some of the existing ground water studies and ground water planning documents overlap the geographic boundaries of the planning area and include the drainage basins of the Little Missouri, Belle Fourche, Cheyenne and Niobrara Rivers.

Other objectives are as follows:

It is intended that the information provided herein along with the GIS data layers and the bibliography of previous investigations will provide a starting point for site specific ground water investigations.

Study Methods

There were no original investigations performed as part of this task. The work consisted of performing an inventory, compilation, and review of published literature on the geology and ground water resources of the planning area.

There is a wealth of published and unpublished reports of investigations on the geology and ground water resources of the planning area. The geology of the PRSB has been the subject of investigation and exploration as a result of interest in the development of energy and natural resources for at least the last 40 to 50 years. Resources of interest have included oil and gas, coal, uranium, coalbed methane and water.

A bibliography of published ground water studies and ground water planning documents for the Basin Plan is included in the .Available Ground Water Determination. technical memorandum. The references included in the bibliography, provide sources for an overview of ground water resources, and of some of the interests and concerns that have arisen as a result of the various stages of development of energy and natural resources in the planning area.

Additional information in specific geographic areas within the planning area is available through the U.S. Geological Survey (USGS) and other federal agencies. Two additional federal agencies active in ground water related issues in the PRSB include the Bureau of Land Management (BLM) and the U. S. Environmental Protection Agency (USEPA).

Several Wyoming State agencies have site specific information available in the planning area. These agencies include the Department of Environmental Quality (Land Quality and Water Quality Divisions), the State Engineer's Office, the United States Geological Survey, the Oil and Gas Conservation Commission and the Water Development Commission.

Overview

The planning area lies in the central and northcentral part of the state and includes all or part of six Wyoming counties (Figure I-1). The planning area includes all of Sheridan and Johnson Counties, about sixty percent of Campbell County (north, centralwest and southwest) and a small portion of northeastern Natrona County. Very small parts of west and southeast Converse and Washakie Counties are also within the planning area. Figure III-21 shows the general location of the planning area with respect to regional structural elements in northcentral and northeastern Wyoming.

Major communities in Sheridan and Johnson Counties include Arvada, Ucross, Clearmont, Dayton, Ranchester, Sheridan, Buffalo and Kaycee. Edgerton and Midwest are the primary towns in Natrona County. Gillette in Campbell County lies on the eastern edge of the planning area.

Regionally, the planning area lies within the Missouri River drainage system and covers an area of approximately 11,261 square miles in central and northcentral Wyoming. The principal surface water systems within the planning area include the Tongue, Powder, and Little Bighorn Rivers and their respective tributaries. These drainage systems form the boundary of the Basin Plan.

Altitudes are variable in the planning area and generally range from 3,460 feet where the Tongue River crosses the State line into Montana in Sheridan County to 13,165 feet at the summit of Cloud Peak in Johnson County. East of the Mountains in Johnson County, relief is about 2,000 feet with altitudes ranging from 3,700 feet to an average of about 5,700 feet in the foothills at the base of the Bighorn Mountains. Altitudes in Natrona County range from 9,800 feet in the northwest part of the County to 4,800 feet near Midwest.

Climate is typical of the northern High Plains with low precipitation, high evaporation and wide ranges of temperatures. Annual precipitation varies from 13 to 15 inches in the majority of the planning area (Figure I-2). Generally, about forty to fifty percent of the precipitation in the planning area occurs between April and June.

Geologic Setting

Geologic formations in the planning area range in geologic time from Precambrian crystalline rocks to recent alluvial and eolian deposits generally consisting of clays, silts, sands and gravels. The PRSB has over 17,000 feet of sedimentary strata. These sedimentary rocks have been divided into about 11,000 feet of Cambrian to Cretaceous pretectonic deposits and up to 7,000 feet of Tertiary deposits associated with the deformation of the PRSB.

The older strata, which are exposed only in the western part of the planning area, are economically important for oil production. The Tertiary deposits contain significant coal reserves and are subject to mining and coalbed methane development. Both the Early Cretaceous Fall River Formation and the Early Tertiary Wasatch Formation have been important as uranium deposit sources in the Black Hills and the PRSB outside the planning area. Figure III- 22 presents a generalized geologic section of the PRSB typical of the planning area.

The Powder/Tongue River Basin encompasses several tectonic elements that influence the geology, and the occurrence and availability ground water. These structural features include the PRSB, mountain uplifts (Bighorn Mountains, the Laramie Range and Black Hills (outside and east of planning area)) and broad uplifts of lesser magnitude (Casper Arch and Hartville Hills).

Figures III-23 and III-24 present the generalized surficial and bedrock geology of the planning area.


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Geologic Units and Ground Water

A geologic formation is a body or group of rock strata that consist dominantly of a certain lithologic type or combination of types. A general definition of an aquifer is a geologic formation or group of formations that are capable of yielding a significant quantity of water to wells or springs.

There are more than 30 geologic formations exposed on the western margin of the planning area. For this report, the formations were grouped into five principal aquifer systems that have historically been the major ground water sources of interest in the planning area. The grouping was based on that presented in the 1981 report on the "Occurrence And Characteristics of Ground Water in The Powder River Basin, Wyoming", by the Water Resources Research Institute (WWRI) of Wyoming. Figure III-25 graphically summarizes the geologic formations and their hydrogeologic role in the PRSB.


The WWRI aquifer system division and the grouping used herein were based on aquifer hydrogeologic similarity and aquitard identification. The grouping allows for a simplified presentation of the principal sources of ground water in the planning area. The five major aquifer systems within the planning area are (oldest to youngest):

More detailed information on the hydrogeology and hydrologic characteristics of the major aquifer systems are provided in the .Available Ground Water Determination. memorandum.

Ground Water Quality

Ground water quality data contained in USGS ground water reports for the planning area were reviewed and provide an overview of the general quality of water from the aquifer systems within the planning area.

The review included selected USGS analyses available from USGS data files as of March 26,1982 (Larson and Daddow, 1984). The 2000 USGS publication on water co-produced with coalbed methane in the PRSB was also reviewed (Rice, Ellis and Miller, Water Co-produced with Coalbed Methane in the Powder River Basin, Wyoming: Preliminary Data).

1984 USGS Report

Information used in the 1984 report did not include all of the data available in USGS files at the time. Constituents were selected by USGS on the basis of their relative abundance and their inclusion in water quality criteria at the time. Water quality data available from the 1984 USGS report included: specific conductance, pH, temperature, dissolved-solids (TDS) concentration and concentrations of the major ions (calcium, magnesium, sodium, potassium, alkalinity (as bicarbonate), sulfate, chloride, fluoride, and nitrate, plus silica, boron, and iron). This data was from 748 ground water sites in the PRSB and adjacent areas.

Information on selected dissolved trace metals were reported for 220 ground water sites in the PRSB and adjacent areas in the 1984 USGS report. Data were reported for nine trace metals (arsenic, barium, cadmium, chromium, copper, lead, mercury, selenium, zinc) in the 1982 selection.

Radiochemical data was listed for 65 ground water sites in the PRSB and adjacent areas in the 1984 USGS report. The data included eight radiochemical analyses for each site (gross alpha- dissolved, gross alpha-suspended, gross beta-dissolved, gross beta-suspended, radium 226 dissolved radon method, radium 226 dissolved precipitation method, uranium-dissolved extraction method, uranium-dissolved direct fluorometric method).

2000 USGS Report

The 2000 USGS publication on water co-produced with coalbed methane in the PRSB contained data from 47 ground water sites in the PRSB. Approximately 15 of the sites were located within the planning area. The remaining 32 were located in the Northeast Wyoming River Basins Plan Area.

Water quality data available from the 2000 USGS report included: pH, temperature, dissolved- solids (TDS) concentration and concentrations of the major ions and minor ions (fluoride, chloride, sulfate, bromine, alkalinity, ammonia, calcium, potassium, magnesium, sodium, barium, iron plus silica, strontium, and sodium-adsorption-ratio (SAR)). Data were also reported for seventeen trace elements (silver, aluminum, arsenic, boron, beryllium, bismuth, cadmium, cerium, cobalt, chromium, caesium, copper, mercury, lanthanum, lithium, manganese, nickel).

Water Quality Standards and Suitability for Use

The State of Wyoming has identified the following standards for different classes of ground water:

Historically, major ground water uses in the PRSB and the planning area have been for domestic use, agriculture (stock and irrigation), and municipal / public water systems. Ground water has been used for industrial purposes including, coalbed methane production, petroleum production (secondary oil recovery) and coal mining, coal fired steam generation, and uranium mining and processing. Ground water has also been used for fish hatcheries in the eastern part of the PRSB outside the planning area.

The fact that ground water is and has been successfully used for the above uses is a general, practical indicator of ground water quality in the planning area. A general, qualitative evaluation and comparison of ground water produced from the six aquifer systems was performed. The results of the evaluation, including a general characterization of water co-produced with coalbed methane, are summarized in Table III-34 along with the availability and development potential for each aquifer system in the planning area.

Table III-34
Summary of Ground Water Availability/Development Potential of Major Aquifer Systems,
Central and Western Flanks of the Powder River Structural Basin
Major Aquifer System Geologic Unit Thicknes
(Feet)
Lithologic Character Hydrological CharacterA,B General Water Quality Availability / Development PotentialC Remarks
Quaternary Alluvial Aquifer System Alluvium and Terrace
Deposits
0-100+ Silt, sand and gravel; unconsolidated and interbedded; present along most streams. Yield of 50 to 300 gpm may be possible, often through induced recharge. Terraces topographically high and often drained. Specific capacity, 0.3-7 gpm/ft; permeability, 380 and 1100 gpd/ft2 and transmissivity, 9700 and 20300 gpd/ft from two tests in Sheridan County (Lowry and Cummings, 1966). Coarser deposits have better aquifer properties. TDS content generally range from about 100 to >4000 mg/l. Chemical characteristics of water differ geographically. Chemical type and mineralization of the water can be expected to vary depending on underlying rock types and the nature and degree of interconnection with surface water. Alluvial deposits in the western part of the planning area generally contain water of better quality than alluvial deposits in the eastern part. Suitability for municipal / public, domestic, irrigation and stock is variable and dependent on location and above factors. Historical source for municipal / public, domestic and stock use. Production has ranged up to 250 gpm with induced infiltration of surface water. Ground water development potential generally better in coarse-grained deposits and poorer in fine-grained materials. Moderate to high yields might be possible to optimally located and properly designed wells if induced infiltration from surface water can be tolerated in the upper reaches of Powder River, Piney, Clear and Crazy Woman Creeks. Moderate supplies may be able to be developed in thicker deposits of coarse material in the alluvuim of Prairie Dog Creek as well as the alluvium of the Tongue River and Dutch Creek. (Lowry and Cummings, 1966), (Whitcomb, Cummings and McCullough, 1966) Quaternary alluvial aquifers generally in hydraulic connection with all bedrock aquifers in outcrop areas and also with surface waters. Alluvial aquifers in larger valleys provide hydraulic interconnection between otherwise hydraulically isolated bedrock aquifers (Whitcomb, 1965). Alluvial aquifers also serve as interchange point and storage for ground water in the hydrologic cycle (Davis and Rechard, 1977), (Davis, 1976). Induced recharge from surface waters is probable in areas of extensive development.
Fort Union / Wasatch Aquifer System Wasatch Formation 500 to 2000± Fine- to coarse-grained lenticular sandstones interbedded with shale and coal. Yields water from, lenticular sandstone and to a lesser extent from jointed coal and clinker beds (Hodson, Pearl and Druse, 1977). Divided into two conglomeratic members (Kingsbury and Moncrief Members) near the Bighorn Mountains (Lowry and Cummings, 1966). Yields generally <15 gpm. Specific capacity of Wasatch wells and those completed in the coarse grained facies of the Wasatch Formation in Sheridan County averaged 0.33 and 1.0 gpm/ft respectivley; permeability, 6.5 gpd/ft2 (one test - coal, Sheridan County); transmissivity, 520 gpd/ft (one test - coal, Sheridan County) and 2200 gpd/ft (one test - sandstone, Sheridan County). (Lowry and Cummings, 1966) TDS content of waters is variable and ranges from 141 to 6620 mg/l (Larson, 1984). Sulfate and Iron content range from 0.6 - 4080 mg/l and 0 - 25 mg/l respectively and water varies from soft to very hard. Dominant cations generally are Sodium, Calcium and Magnesium, Sodium and Calcium, or Sodium and Magnesium. (Lowry and Cummings, 1966), (Whitcomb, Lowry and McCullough) Important local source for domestic and stock water supply. Yields from fine grained facies generally small and barely adequate for stock and domestic use and generally can be expected to be < 15 gpm. Wells completed in the Kingsbury Conglomerate and Moncrief Members may have potential for higher production. Water quality generally suitable for domestic supplies although undesireable constituents may make other water sources more attractive if available. Water quality suitability for stock ranges from poor to good. Generally unsuitable for irrigation due to high salinity and sodium content. Kingsbury Conglomerate and Moncrief Members located at the base of the mountains in Sheridan Counties.
Fort Union Formation 1200-3900 Sandstone, fine- to medium-grained, lenticular, interbedded with siltstone, coal and shale. "Clinker" associated with coal outcrops. Flowing yields of 1-60 gpm reported where confined. Pumped yields up to 250 gpm with several hundred feet of drawdown (eastern Campbell County, east of planning area). Specific capacity for 85 wells in Sheridan County averaged 0.42 gpm/ft; permeability (2.5 and 7.9 gpd/ft2), transmissivity (10 and 95 gpd/ft), and Storage coefficient (9.0 X 10-5 and 3.5 X 10-4) for tests performed on two wells in Sheridan County (Lowry and Cummings, 1966). Coal and clinker generally better aquifer properties than sandstones. Locally clinker transmissivity up to 3,000,000 gpd/ft; Anisotropy and leaky confining layers are common. TDS content of waters is variable and ranges from 484 - 4630 mg/l (Larson, 1984). Sulfate and Iron content range from 0.3 - 1870 mg/l and 0.06 - 19 mg/l respectively. Water varies from soft to very hard and is generally a Sodium Bicarbonate type. (Lowry and Cummings, 1966), (Whitcomb, Cummings and McCullough, 1966) Water co-produced with coal bed methane is predominantly Sodium Bicarbonate type with TDS content and SAR (15 samples), of 540 - 2010 mg/l (mean of 1309 mg/l) and 7.7 - 32 (mean of 19.82) respectively in planning area. (Rice, Ellis & Bullock, 2000). BLM Wyodak EIS assumed average TDS concentration of 764 mg/l (USDI,BLM, 1999). Important, extensively used relatively shallow (< 1000 feet depth) local source for domestic and stock supply. Low yields, generally less than 25 gpm can be expected. Four of the 12 municipal / public supply wells in service for the City of Gillette (east of planning area) as of 1994 had been tested at pumping rates ranging from 50 to 130 gpm (Wester -Wetstein and Associates, Inc., 1994). Total of 6820 Coal Bed Methane wells permitted with WSEO in planning area as of 12/31/00. Maximum, minimum and mean depths and range of actual yields listed on permits were 92 -4100 (mean 637) feet below ground surface (bgs), and 1 - 60 (mean 49) gpm respectively. Range of depths to main water bearing zone listed on WSEO Permits were 58 - 3816 (mean 580) feet bgs. BLM Exxon Pistol Point EA assumed average water production for each CBM well to average between 30 and 45 gpm (USDI,BLM, 1992). BLM Lower Prairie Dog Creek EA assumed average water production for each CBM well to be 15 gpm (USDI,BLM, 1999). BLM Wyodak EIS assumed average expected water production to be 12 gpm over the estimated 12 year life of each CBM well (USDI,BLM, 1999). BLM Wyodak Drainage EA assumed average water production for each CBM well to be 11.1 gpm (USDI,BLM, 2000).
Fox Hills/Lance Aquifer System Lance Formation 600-1900
(North)
1950-3000
(South)
Sandstone, fine- to medium-grained, lenticular, interbedded with sandy siltstone, claystone and shale. Generally yields less than 15 gpm with specific capacities, 0.03-.16 gpm/ft in planning area. Limited development due to uneconomical drilling depths. In eastern area of Powder River Structural Basin (PRSB), yields up to 350 gpm but with large drawdowns and long well completion intervals; permeability 34 gpd/ft2; transmissivity, 76-2100 gpd/ft for wells also completed in Fox Hills Sandstone. TDS content in waters generally range from <500 - 3060 mg/l. Composition variable, mainly Sodium Sulfate or Calcium Sulfate. Variable iron ( 0 - 6.03 mg/l) and Sulfate (<100 - 1780 mg/l) content, SAR 1.9 - 39. Generally undesireable for domestic water source due to possible high Iron, Manganese and Sulfate content. Generally fair to poor for stock use. Unsuitable for irrigation due to high salinity and / or high SAR. Historical source for domestic and stock supply. Generally yields less than 15 gpm in planning area. Development limited due to uneconomical drilling depths. Water quality generally suitable for domestic supplies although undesireable constituents may make other water sources more attractive if available. Water quality suitability for stock ranges from poor to good. Generally unsuitable for irrigation due to high salinity and / or Sodium content.
Fox Hills Sandstone 0-700 Sandstone, fine-to medium-grained, interbedded with shale and siltstone. Generally yields less than 15 gpm with specific capacities, 0.03-.37 gpm/ft in planning area. Transmissivity, 76-1600 gpd/ft for wells also completed in Lance Formation. Limited development due to uneconomical drilling depths. Similar to Lance Formation. Water suitable for domestic use usually present only near outcrop. Water suitable for stock use generally found at depths of up to 1000 feet, away from outrop. The quality of water may be unsatisfactory for domestic and stock use where the the aquifer is is deeper than 1000 feet. (Crest and Lowry, 1972) Historical source for municipal / public, domestic and stock supply. Generally yields less than 15 gpm in planning area. No more than 50 gpm can be expected from wells completed in wells in the planning area (Natrona County). Well for Town of Edgerton produced 25 gpm with a specific capacity of 0.037 gpm/ft. (Crist and Lowry, 1972) Development limited due to uneconomical drilling depths. Tested yields of Gillette municipal / public supply wells (east of planning area) have ranged from 85 to 705 gpm (Wester-Wetstein and Associates, Inc., 1994). High Fluoride content may be of concern in eastern part of planning area. Has been used as municipal / public water supply source for Town of Edgerton. Has been used for oil well water flooding operations in eastern PRSB.
Dakota Aquifer System Muddy Sandstone
(NewCastle Sandstone)
0-40± Light gray, fine-grained, lenticular sandstone and siltstone often termed a member of Thermopolis shale. Minor unit of Dakota Aquifer System. Oil field data (PRSB): porosity, 5-20%; permeability, <7 gpd/ft2 ; transmissivity, <150 gpd/ft. No data in planning area. No data in planning area. Ground water possibilities in planning area generally not known. Probably capable of yielding small quantities of no more than 10 gpm water to wells. Deep drilling depths would probably preclude consideration other than at outcrops. Dakota Aquifer System historical source for domestic and stock use in eastern PRSB.
Cloverly Formation 140-150 Interbedded dark shale and brown siltstone with 15-45 feet of basal, fine - to coarse-grained well sorted sandstone. Flowing yields of 1-40 gpm, up to 250 gpm reported for pumped wells (south of planning area); specific capacity, 0.12-.2 gpm/ft. Oil field data: porosity, 15-18%; permeability, 0.4-4 gpd/ft2; transmissivity, 7-230 gpd/ft. Water from Cloverly and Morrison Formations in Natrona County predominantly Sodium Bicarbonate type. Other types include Calcium Bicarbonate, Calcium Sulfate, Sodium Sulfate, and Calcium Sulfate. TDS content range between 300 and 3000 mg/l. Generally deeply buried in planning area except at outcrops. Yields small supplies to springs at outcrops. Well yields of 5 to 20 gpm may be expected. Yields of greater than 100 gpm may be possible from complete section of rocks.
Madison Aquifer System Tensleep Sandstone 50-250
(Northwestern Basin)
<500
(Southwestern Basin)
Fine- to medium-grained, massive, crossbedded sandstone with occasional thin dolomite beds. Unit of Madison Aquifer System. Flowing yields up to 400 gpm; Specific capacity, 1 gpm/ft. Oil field data: porosity, 0-24%; permeability, 0-21 gpd/ft2; transmissivity, 0-1900 gpd/ft. Water type is variable ( Magnesium Carbonate, Calcium Magnesium Sulfate, Sodium Sulfate,Calcium Sodium Sulfate, Calcium Sulfate) and concentration of TDS varies directly to distance from the outcrop and generally ranges from<300 -3240 mg/l. Generally very hard but suitable for domestic, stock and irrigation use at or near outcrop. (Crist and Lowry, 1972), (Whitcomb, Cummings and McCullough, 1966) TDS content 204 - 2930 mg/l in six samples in Natrona County (Larson, 1984). Sandstone generally well cemented, but primary permeability is sufficient at most locations to permit yields of 50 gpm to wells. There is potential for higher yields where secondary permeability is high. Yield of 600 gpm reported for an irrigation well at the foot of the Bighorn Mountains in Johnson County . Development may be limited economically due to deep drilling depths in Johnson County in outcrop area or in narrow belt generally less than about one mile paralleling the east margin of the outcrop. (Whitcomb, Lowry, and (McCullough 1966), (Crist and Lowry, 1972)
Amsden Formation 150-300
(Northwestern Basin)
0-200
(Southwestern Basin)
Red and purple shale with some sandstone, cherty dolomite and limestone. Aquitard unless fractured.
Generally deeply buried in planning area except at outcrops. Ground water possibility generally not known.
Madison Limestone 1100±
(Northwestern Basin)
200-400
(Southwestern Basin)
Limestone, dolomitic limestone and dolomite, sandy at base Principal unit of Madison Aquifer System. Flowing yields over 4000 gpm but highly variable; specific capacity. <1 to 50 but is flow-dependent; transmissivity, 500-90,000 gpd/ft or higher and highly variable. Waters at Outcrop (TDS < 600mg/l, predominantly Calcium Magnesium Bicarbonate type water). TDS increase basinward to > 3,000 mg/l, Sodium Sufate Chloride predominating. Fluoride enrichment characteristic of Madison System waters throughout the PRSB basin. Concentrations of radionuclides could be of concern in some areas. Probably most important high yield aquifer in Wyoming. Historical source for municipal / public water supply, industrial, irrigation and stock use in PRSB. Several fish hatcheries use Pahasapa / Madison aquifer as water source in northeastern part of PRSB. Yields variable geographically and dependent on secondary permeability. Drilling depths may inhibit development. Total estimated recharge to the Madison Limestone in the PRSB in 1973 was about 75,000 acre feet/year. (WSEO, 1976)
Bighorn Dolomite 400-500
(Northwestern Basin)
absent
(Southwestern Basin)
Massive dolomite, becoming thin-bedded at top and sandy at base Generally deeply buried except in outcrop areas. Ground water possibilities generally not known.
Ground water possibilities generally not known. Probably would yield water to wells depending on secondary permeability.
Flathead Sandstone 345±
(Northwestern Basin)
90
(Southwestern Basin)
Tan to reddish sandstone, locally conglomeratic, interbedded with green shale and siltstone. Minor unit of Madison Aquifer System. Not exploited due to deep burial but a few wells yield water near outcrops.
Ground water possibilities generally not known. Probably would yield water to wells depending on secondary permeability. Generally deeply buried except in outcrop areas. Yields small quantities of water to springs from sandstone and conglomerate in the Bighorn Mountains. (McCullough 1966), (Crist and Lowry, 1972)

AReported yields may reflect development needs rather than aquifer capability; higher yields canm sometimes be expected, with corresponding drawdown increases. Reported water well transmissivities or permeabilities may be for wells completed in two aquife
BOilfield (and USGS test) data are variously derivied resulting in internal inconsistencies in this compilation. Permeabilities are measured on cores or derived from other data and transmissitivities are from drill stem tests or calculated from permeability
CActual development potential will require site specific affice and field investigations to define aquifer capability and constraints unique to each project and site.

Take from: Feathers, Libra, Stephenson and Eisen, 1981, Occurance and Characteristics of Groundwater in the Powder River Basin, Wyoming

Aquifer Sensitivity/Vulnerability

The Wyoming Spatial Data and Visualization Center (SDVC . now known as the Wyoming Geographic Information Science Center or WyGISC) developed a system to assess the sensitivity and vulnerability of ground water to surface water contamination in Wyoming. The SDVC developed aquifer vulnerability maps to define the potential for surface contamination to impact ground water in the uppermost aquifer throughout Wyoming. The highest rated lands generally are located on alluvial deposits adjacent to rivers, streams, and lakes, and are associated with slope wash, colluvium, residium and eolian deposits or are on fractured bedrock areas.

Maps of aquifer vulnerability to contamination for the uppermost or shallowest aquifers were also developed by SDVC. Ground water is vulnerable in areas with high water tables, sandy soils, and areas of presumed pesticide application. The areas with the highest vulnerability are also generally located in the floodplains of the major streams and/or associated with slope wash, colluvium, residium and eolian deposits within the planning area.

The ground water sensitivity and vulnerability maps are provided in the .Available Ground Water Determination. memorandum.

Ground Water Development

Ground water is the major source of water for many uses within the planning area. All five aquifer systems are important water sources in the planning area for all uses. Ground water associated / co-produced with coalbed methane development although not a use, is very important due to withdrawal impacts on ground water levels and existing wells completed in the Fort Union/Wasatch Aquifer System.

Existing Development

Selected existing and historical uses of ground water from the five aquifer systems within the planning area are summarized in Table III-34. The significance of ground water in the planning area is demonstrated by the 16,432 active ground water permits (as of December 31, 2000) within the planning area. Because of the dynamic nature of CBM development, the inventory of permitted CBM wells was updated to reflect data as of December 31, 2001. The number of permits for each use category are summarized below:

The geographic distribution of the permits for the above use categories with respect to surficial and bedrock geology are presented in the .Available Ground Water Determination. memorandum. Two of these maps showing CBM wells and stock wells in relation to the bedrock geology are shown on Figures III-26 and III-27. These maps provide a general indication of the significance of the geologic formations associated with each of the aquifer systems as ground water sources in the planning area.


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Ground Water Monitoring Programs

Existing ground water monitoring programs will continue to be important in monitoring the status of ground water in the PRSB and the planning area for all activities. One such program is the Wyoming statewide USGS cooperative program operated by the SEO and other state, county, municipal and federal agencies.

The Gillette Area Groundwater Monitoring Organization (GAGMO) and the recently formed (April 1999) Powder River Basin Area Groundwater Monitoring Organization (PRAGMO) are for coal mining and coalbed methane development. GAGMO is operated by the coal mining industry and PRAGMO by the coalbed methane development operators. These programs provide a common database that satisfy federal and state agency requirements for the respective industries to track and evaluate impacts of their operations on ground water in the PRSB.

Other state and federal agencies have their own monitoring programs associated with their management and regulatory responsibilities. State agencies include SEO, Oil and Gas Conservation Commission and the Department of Environmental Quality. Federal agencies include the Bureau of Land Management and the Forest Service.

Agricultural, Municipal, Industrial and Misc., Domestic and Stock Uses and Ground Water

Out of a total of 16,432 active ground water permits inventoried as of December 31, 2000, for the basin plan, 9,612 of the permits were for WWDC categories other than coalbed methane development.

Reported well depths for the 111 active permitted agricultural wells with production rates greater than 49 gpm ranged from 3 to 4,689 feet and averaged 720 feet. Reported depths to the top of the "main water bearing zones" in the permit data ranged from 3 to 4,418 feet and averaged 657 feet. The maximum and average reported "actual yields" of these wells were 2700 gpm and 280 gpm.

There were a total of eight permitted active municipal wells with production rates greater than 49 gpm. Reported well depths ranged from 18 to 4,170 feet and averaged 1,282 feet. Reported depths to the top of the "main water bearing zones" in the permit data ranged from 11 to 2,680 feet and averaged 716 feet. Reported "actual yields" of these wells ranged from 70 to 990 gpm and averaged about 399 gpm.

There were a total of 301 permitted active industrial and miscellaneous wells with production rates greater than 49 gpm. Reported well depths ranged from 9 to 15,400 feet and averaged 1,987 feet. Reported depths to the top of the "main water bearing zones" in the permit data ranged from 4 to 9,722 feet and averaged 1,666 feet. Reported "actual yields" of these wells ranged from 50 to 9,479 gpm and averaged about 375 gpm.

A total of 4,646 permitted domestic wells were reported in the planning area. Reported domestic well depths ranged from 1 to 9,600 feet and averaged 216 feet. Reported depths to the top of the "main water bearing zones" in the permit data ranged from 1 to 4,070 feet and averaged 180 feet. Reported "actual yields" of these wells in the permit data files ranged from 1 to 1,800 gpm and averaged about 13 gpm.

A total of 4,546 permitted stock wells were reported in the data for the planning area. Reported stock well depths ranged from 1 to 9,537 feet and averaged 329 feet. Depths to the top of the "main water bearing zones" ranged from 1 to 6,533 feet and averaged 291 feet. Reported "actual yields" of these wells ranged from 1 to 2,700 gpm and averaged about 14 gpm.

The relative importance of each of the aquifer systems to each use category is summarized in Table III-34. This information together with the maps provided in the Available Ground Water Determination Technical Memorandum can be used to make further inferences at an initial level, as to the relative importance of each of the aquifer systems with respect to the five non-coalbed methane use categories in the planning area.

Impacts on Ground Water and Surface Water Supplies

Impacts to ground water will depend on local geologic and hydrologic conditions in the areas of development. Possible impacts to ground water could include:

Coalbed Methane Development and Ground Water

For ease of reference, the main coal seam that is the target of coalbed methane development in the PRSB and within the planning area is referred to as the Wyodak-Anderson coal zone. Methane gas is trapped in micropores and cleat fracture systems within the coal, and is maintained in that state by the natural pressure of ground water. The gas is extracted using wells that are completed in the coal to remove water and lower the water pressure responsible for holding the gas. The gas moves out of the coal as the water pressure is lowered, and is recovered from the well along with the water.

As previously noted, a total of 9,393 coalbed methane wells (December 31, 2001) were identified through the SEO data query for the Basin Plan. Reported coalbed methane well depths ranged from 92 to 15,220 feet and averaged 712 feet. Reported depths to the top of the "main water bearing zones" in the permit data ranged from 58 to 3816 feet and averaged 653 feet. Reported "actual yields" of coalbed methane wells in the permit data files averaged 37 gpm.

The BLM has recently used 12 gpm (USDI, 1999, Wyodak Coalbed Methane Project Final Environmental Impact Statement) and 11.1 gpm (USDI, 2000, Wyodak Drainage Coalbed Methane Environmental Assessment) for average production rates of coalbed methane wells in the preparation of Environmental Impact statements for coalbed methane development within the planning area. The actual ground water production rate is typically variable throughout the life of each well. As an example, BLM projected the initial ground water production rates of the wells for the Lighthouse Coalbed Methane Project to be 11 gpm, with an interim average of 7 gpm and a final rate of less than 3 gpm per well (USDI, 1995, Lighthouse Coalbed Methane Project Environmental Assessment).

The USGS, in cooperation with BLM and coalbed methane production companies, is conducting multidisciplinary studies in the PRSB in an effort to provide a better understanding of coalbed methane resources and associated water. A USGS report for one of the studies in progress provides preliminary compositional data on water from 47 coalbed methane wells sampled between June, 1999 and May, 2000. Water co-produced with coalbed methane is generally a sodium bicarbonate type. Of the 47 wells sampled by USGS, 15 are located within the area of the Powder/Tongue River Basin Plan and 32 are located within the Northeast Wyoming River Basins Plan Area. Total dissolved solids content (TDS) of all 47 samples ranged from 270 to 2010 and averaged 850 mg/l. Values of the sodium adsorption ratio ((SAR), which is a relative measure of the suitability of water for irrigation due to sodium content) for the 47 samples ranged from 5.7 to 32 and averaged 12. For comparison, an SAR of roughly 13 would generally be considered the upper limit for field crops in clayey soils.

TDS and SAR of the 15 samples from coalbed methane wells in the planning area ranged from 540 to 2010 mg/l (mean 1309 mg/l) and 7.7 to 32 (mean 19.82) respectively. TDS and SAR of the 32 samples from coalbed methane wells in the Northeast Wyoming River Basins Plan Area ranged from 270 to 1170 mg/l (mean 653 mg/l) and 5.7 to 12 (mean 7.85) respectively. The results of the USGS samples indicated that TDS and SAR in waters in the Wyodak-Anderson coal zone generally increase in the PRSB from south to north and from east to west.

Concentrations of most of the 17 trace elements analyzed by USGS in samples of water from the 47 coalbed methane wells were below detection limits. All the concentrations of trace elements were below the maximum contaminant levels of the Primary Drinking Water Standards of the USEPA. The USGS reported that there were no noticeable trends in trace element concentrations in the samples from the 47 wells.

Impacts on Ground Water and Surface Water Supplies

Potential impacts to ground and surface water have been identified by BLM in the preparation of environmental assessments (EA) and environmental impact statements (EIS) for numerous coalbed methane projects in the PRSB including the planning area. Impacts to ground water will depend on local geologic and hydrologic conditions in the areas of coalbed methane development. Possible impacts to ground water that have been identified include:

Possible surface water related impacts that have been identified could include: A more comprehensive discussion of all possible impacts including those to both surface and ground water due to coalbed methane development is available in the previously mentioned EA.s and EIS.s prepared by BLM.

Future Development

The geology, drilling depths, hydrogeologic characteristics and ground water quality of aquifer systems vary throughout the planning area. All of the aquifer systems in the planning area previously discussed probably have some potential for development. Site specific investigations in conjunction with experience and common sense will be required to determine the opportunities available to develop ground water with wells of sufficient capacity for a specific use within the planning area.

Although there have been considerable hydrogeological investigations in the PRSB including the planning area, there have been few regional assessments of the annual recharge, storage and sustained yield capability of the major aquifer systems both in the PRSB and the planning area. General conclusions regarding ground water development potential of four of the five major aquifer systems in the planning area discussed in this report are summarized below:

Table III-34 summarizes the development potential of the five aquifer systems within the planning area. Items of interest related to ground water availability/development potential are also summarized in Table III-34. These items include the general lithologic and hydrologic character of the aquifer systems in addition to the general quality of ground water available from the systems.