Wyoming State Water Plan, Wyoming Water Development Office
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Northeast Wyoming River Basins Water Plan
Technical Memoranda

SUBJECT: Appendix D
Agricultural Water Use

PREPARED BY: HKM Engineering Inc.

DATE: February 2002


INTRODUCTION

Water use for agriculture represents the greatest consumption of water within the boundaries of the Northeast Wyoming River Basins Plan area. A reasonable estimate of existing irrigation water use is therefore central to a comprehensive water use inventory. Estimates of water use by irrigated agriculture can generally be divided into the following three components:

  1. Quantity of irrigated lands
  2. Types of crops grown and geographic distribution
  3. Amount of water consumed by the crops
Appropriate estimates of each of these three components are essential to reasonable estimates of water use by irrigated agriculture.

The irrigated lands mapping work indicates a total of 86,882 acres of irrigated agriculture in the planning area. Of this total, 9,531 acres are currently idle. In addition, 1,636 acres are currently undergoing development and gradually being removed, to varying degrees, from traditional agriculture. There are also 30,269 acres of irrigation served by spreader dikes or 'kick-out" ditches in the planning area (Irrigation Classification S and H). The remaining area (45,446 acres) is comprised of full-service or partial service irrigation or man-induced subirrigation (Irrigated Lands Mapping and Water Rights Data, HKM, 2002).

Also from the recent irrigated lands mapping work, together with agricultural statistics and interviews with SEO Hydrographer / Commissioners and area landowners, the primary irrigated crops grown in the basin are forage crops (alfalfa and grass hay or pasture grass) accounting for 95 percent of the actively irrigated acreage. Small grains and corn account for the remaining 5 percent of the irrigation (Irrigated Crops, HKM, 2002).

The methodology used to determine the amount of water consumed by the irrigated crops (depletions), and the diversion demands is the primary subject of this memorandum.

The Northeast Wyoming River Basins planning area is unique in that stock ponds are a relatively significant contributor to the total agricultural water use in the planning area. The cumulative surface area of these stock ponds results in a significant consumption of water through evaporation. The methodology used to estimate the evaporative loss from stock ponds in the planning area is also discussed in this memorandum.

HISTORY OF AGRICULTURAL WATER USE IN THE BASINS

Irrigated agriculture in the Northeast Wyoming River Basins planning area is primarily associated with forage production for the livestock industry. Ranchers depend on irrigated cropland to provide winter feed and summer grazing for a successful ranching enterprise. According to the 1972 Framework Water Plan, over 80 percent of the water consumed by man's activities in the planning area is used for irrigation.

Early in Wyoming's history, ranchers had discovered that successful farming required irrigation. By the 1890's, many ranchers were taking advantage of cheap irrigation of bottomlands along the small tributary streams, but most of the water from the large rivers was being carried, unused, into other states (SEO, 1972). As the direct flow supply of the streams became fully appropriated, reservoirs were constructed, where suitable sites could be found, to store spring runoff for late-season irrigation uses. One of the most significant of these to the planning area is Keyhole Reservoir with and active capacity of roughly 190,000 acre-feet. This reservoir which was completed in 1952 provides supplemental storage for irrigated lands predominately located in South Dakota. Ten percent of the reservoir capacity, however, is reserved for the Crook County Irrigation District and Shattuck Hills in Wyoming in accordance with the Belle Fourche River Compact. There are a total of 6 significant storage facilities in the Northeast Wyoming River Basins planning area with capacities in excess of roughly 1000 acre-feet as well as many smaller facilities, allowing for expanded irrigation use of the natural flows in the planning area (Storage Operation and Description, HKM, 2002).

Agricultural water use has changed little in recent decades with the exception that there has been a progressive shift, in some areas, from flood irrigation practices to sprinkler irrigation.

RELATIONSHIP BETWEEN ACTUAL HISTORIC DIVERSIONS AND THEORETICAL MAXIMUM DIVERSIONS

The amount of irrigation water use is primarily dependent on the number of acres irrigated, the crop water demands, and the amount of water available to meet these demands.

Total crop water demands are dependent on the consumptive use of the crop. The crop consumptive use requirement is the maximum water use of a well-watered crop under optimum growing conditions (Pochop; et.al, October 1992). A portion of the total annual rainfall is available to meet this consumptive use requirement. Effective precipitation is defined as that part of the total rainfall during the growing season which is available to meet the consumptive water requirements of the crops (Dastane, 1974). The remaining consumptive use requirement, unmet by natural rainfall, is referred to as the Crop Irrigation Requirement (CIR).

Knowing the number of acres of irrigation, the types of crops grown, and the climatic conditions, estimates of the theoretical maximum diversions can be made for all of the irrigated lands throughout the basin. In practice however, actual diversions commonly fall short of the amount necessary to meet the full CIR of the crops. This is especially true with direct-diversion, flood-irrigated, forage crops. Actual conditions seldom represent the optimum conditions necessary to achieve maximum water consumption. The objective of this exercise, then, is to compare actual historic diversions, to the extent available, to theoretical maximum diversions in order to develop a relationship that can be used to estimate actual diversions and depletions where records of actual use are unavailable.

The CIR used in this planning effort was provided directly by Dr. Pochop for each month and year of his study period (1951 through 1990), for each crop evaluated, and for each climatic station included (Pochop; et.al., October 1992). Only data specific to the study period of the current investigation (1970 through 1999) was used. Average values were used for those years outside of the Pochop study (1991 through 1999). These CIR values were averaged for the specific wet years, normal years, and dry years selected through the surface water hydrology work to represent these three hydrologic conditions (Surface Water Hydrology, HKM, 2002).

Diversion Records

The methodology utilized by HKM to estimate actual water use by irrigated agriculture is based on records of actual irrigation diversions. Unfortunately, there is very little available data on historical diversions in the Northeast Wyoming River Basins planning area. Diversion records are available only for the Murray Ditch on Redwater Creek and much of this irrigation is located in South Dakota, outside the limits of this planning study (Irrigation Diversion Operation and Description, HKM, 2002). Lacking this information for the planning area, the relationships between actual irrigation water use and theoretical maximum water use based on diversion records for the adjacent Powder/Tongue River Basin planning area are used. The derivation of these relationships and the application to the Northeast Wyoming River Basins planning area is presented herein.

HKM compiled diversion records for approximately 70 key ditches in the Powder/Tongue River Basin planning area as described in the Irrigation Diversion Operation and Description memorandum for the Powder/Tongue River Basin Plan (HKM, 2002). Monthly diversion volumes are summarized as well as the first and last days of irrigation for each year of record. Key ditches to water use in the basin were selected with assistance from the SEO Division 2 Superintendent. These diversions provide a representative coverage of diversion operations in that basin. These records took the form of continuous monthly records as well as periodic instantaneous spot measurements. Missing daily flow records were estimated using the methodology described in the Irrigation Diversion Operation and Description memo for the Powder/Tongue River Basin Plan. Although these records have shortcomings, they represent the best available information regarding actual irrigation diversion amounts.

Service Area Delineation

Lands served by a common supply ditch are grouped together into Service Areas as described in the Irrigated Lands Mapping and Water Rights Data memoranda for the two planning areas (HKM, 2002). In total, approximately 1200 service areas were delineated in the Powder/Tongue River Basin planning area including the service areas for the selected ditches with diversion records. Irrigation in the Northeast Wyoming Basins planning area is divided into 1175 surface water service areas. A crop distribution was assigned to each of these service areas as described in the Irrigated Crops memoranda for the two planning areas (HKM, 2002). Additionally, the representative climatic station(s) were also assigned to each service area. With this information, Crop Irrigation Requirements (CIRs) can be determined for each service area.

Theoretical Maximum Diversion Requirements during Period of Recorded Diversions

Based on conversations with SEO hydrographer/commissioners, the first and last entry in the annual record of diversions for the selected "spot measurement" ditches was sometimes after diversions began in the spring and before diversions ended in the fall. The records for the ditches with "continuous recorders" are less subject to this limitation. In order to provide a common basis for comparison of recorded diversions to theoretical maximum diversions, the CIR was first adjusted to reflect the crop water demand during the recorded period of irrigation. To this end, the number of days of recorded irrigation was determined for each month and year of record and for each of the selected ditches. The average recorded number of days of irrigation for each ditch selected for this study and each hydrologic condition is provided at the back of this memorandum. The average number of days of recorded diversion for the selected ditches in comparison to the representative number of growing days per Dr. Pochop's study are summarized in Table 1 for wet, normal, and dry years.

Table 1
Average Number of Days of Irrigation
Hydrologic Condition Apr May Jun Jul Aug Sep Oct Annual
Wet 1 10 24 28 29 19 0 112
Normal 2 16 25 29 29 18 1 120
Dry 5 18 23 25 23 16 0 111
Average Growing Days
(From Pochop Study)
25 31 30 31 31 30 14 192

Not all of the water diverted for irrigation goes to meeting the CIR, in fact, the CIR often times represents only a minority portion of the total diversion amount. A significant portion of the diverted flow is lost to seepage from the main conveyance ditch, lateral ditches, and field ditches, headgate leakage, evaporative losses from sprinklers, ditch tailwater waste, field wastewater, and deep percolation past the crop root zone. The proportion of water ultimately consumed by the crop to the total volume of water diverted from the stream is referred to as the overall efficiency (Cuenca, 1989). The required amount of irrigation water diverted from the stream to fully meet the CIR during the period of irrigation is then defined as follows:

Theoretical Maximum Diversion Requirement = (Acres x adjusted CIR) / Overall Efficiency
An average annual overall efficiency of 40 percent is used for this study. Efficiency typically varies through the irrigation season and is largely dependent on the ratio of water supplied to the water requirements of the crop. The irrigation efficiency decreases as the amount of water applied relative to the crop water requirement increases (Cuenca, 1989). By way of example, overall efficiency would typically be at a minimum during the early irrigation season when water supply from the snowmelt runoff is abundant but crop water requirements are minimal. Conversely, overall efficiency would typically be at a maximum during the summer months (July and August) when water supply is limited, soil moisture is depleted, and crop water requirements are at a maximum. The overall monthly irrigation efficiency used for this study is shown in Table 2. This efficiency pattern was developed as part of the calibration process for the water availability models developed for the planning area as described in the Spreadsheet Model Development and Calibration memorandum (HKM, 2002).

Table 2
Overall Monthly Irrigation Efficiency
Apr May Jun Jul Aug Sep Oct Annual
25% 30% 45% 65% 60% 30% 25% 40%

Proportion of Actual Historic Diversions to Theoretical Maximum Diversions

The proportion of actual historic diversion volumes to the theoretical maximum diversion volumes during the period of recorded irrigation was calculated for each month and year of record for each of the selected ditches. These proportions were then averaged for each ditch for the wet years, normal years, and dry years. The area-weighted average proportions for the ditches directly serving irrigated lands (excluding transbasin diversion ditches and reservoir supply ditches), are summarized in Table 3.

Table 3
Area-Weighted Average Proportion of Historic to Theoretical Maximum Diversions
Hydrologic Condition Apr May Jun Jul Aug Sep Oct Annual
Wet 3% 40% 69% 78% 75% 79% 5% 73%
Normal 13% 64% 73% 68% 77% 68% 4% 71%
Dry 26% 91% 56% 56% 50% 44% 4% 56%

As shown in Table 3, the average proportion of actual historic diversions to theoretical maximum diversions during the period of irrigation, is at a maximum in wet years (73 %), is somewhat lower in normal years (71 %), and is considerably lower in dry years (56 %).

ESTIMATED ACTUAL HISTORIC DIVERSIONS

As mentioned previously, records of irrigation diversions are not available for essentially any of the irrigation in the Northeast Wyoming River Basins planning area. The proportions presented in the preceding section for the Powder/Tongue River Basin planning area provide a means of making reasonable estimates of actual historic diversions in the Northeast Wyoming River Basins planning area. The crop types, climatic conditions, period of irrigation, overall irrigation efficiency, and number of acres for each service area are used to determine the theoretical maximum diversions across the Northeast Wyoming River Basins planning area. The wet year, normal year, and dry year proportions are then applied to estimate actual historic diversions. The theoretical maximum diversion requirements during the irrigation season and the estimated actual diversions for wet, normal, and dry years are provided in Tables 4 and 5. This information is aggregated into areas represented by the same climate station(s). These climatic areas are shown on Figure 1.

Table 4
Theoretical Maximum Surface Water Diversion Requirements (Acre-Feet)

Source of
Supply
Climate
Stations1
Active
Irrigation
(Acres)
Hydrologic
Condition
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Little
Missouri
River
Colony,
Weston
9,799 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
4,309
4,419
7,974
5,998
7,381
10,251
6,617
8,289
9,450
8,384
8,480
9,522
8,227
7,692
8,033
8,332
8,039
7,954
493
687
1,053
0
0
0
0
0
0
42,361
44,987
54,237
Upper Belle
Fourche River
Gillette 3,312 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
445
707
1,867
1,695
2,136
2,390
2,447
2,546
3,285
2,830
2,721
2,987
2,835
2,594
2,550
2,618
2,436
2,469
26
92
85
0
0
0
0
0
0
12,894
13,233
15,633
Middle Belle
Fourche River
Moorcroft 9,011 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1,074
1,193
2,600
3,760
4,316
6,341
5,284
6,591
8,314
6,381
6,517
6,906
6,988
6,582
7,002
7,059
6,768
6,653
151
209
195
0
0
0
0
0
0
30,697
32,175
38,011
Lower Belle
Fourche River
Colony 5,584 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1,065
1,117
2,500
2,353
3,050
5,913
3,338
4,466
5,374
4,800
4,947
5,360
4,415
4,307
4,360
4,837
4,715
4,385
204
325
468
0
0
0
0
0
0
21,013
22,927
28,359
Redwater
Creek
Sundance 2,213 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
129
198
289
636
746
1,183
1,112
1,508
1,603
1,568
1,766
1,766
1,376
1,551
1,364
1,285
1,342
1,441
4
15
14
0
0
0
0
0
0
6,110
7,127
7,659
Upper Beaver
Creek
Upton 669 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
85
61
134
300
248
533
474
453
547
509
458
558
454
462
429
612
615
601
27
23
18
0
0
0
0
0
0
2,461
2,320
2,821
Middle Beaver
Creek
Newcastle,
Upton
6,000 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
926
734
1,384
2,698
2,286
4,763
4,610
4,495
5,305
4,673
4,371
5,200
3,816
4,167
3,871
5,595
5,670
5,433
216
194
169
0
0
0
0
0
0
22,534
21,927
26,125
Lower Beaver
Creek
Morrisey,
Newcastle
3,561 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
679
737
994
1,414
1,372
2,580
2,257
2,716
3,015
2,094
2,578
2,559
1,787
2,606
2,007
2,483
3,311
2,902
218
287
277
0
0
0
0
0
0
10,933
13,608
14,335
Northern
Tributaries to
Cheyenne
Morrisey 7,958 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1,574
1,710
3,427
2,151
4,700
7,911
5,962
5,726
9,081
4,740
4,873
6,274
5,410
5,382
4,551
4,466
5,512
7,549
1,628
972
1,565
0
0
0
0
0
0
25,931
28,875
40,356
Southern
Tributaries to
Cheyenne
Redbird 12,736 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
2,606
5,609
8,021
7,055
7,900
14,594
10,743
12,199
16,352
9,505
10,931
12,156
10,259
9,871
9,744
10,072
11,755
9,504
80
44
424
0
0
0
0
0
0
50,320
58,309
70,794
Lower
Cheyenne
River
Morrisey,
Redbird
2,602 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
462
501
1,036
667
1,467
2,541
1,939
1,876
2,989
1,549
1,592
2,053
1,751
1,743
1,475
1,447
1,783
2,443
461
279
442
0
0
0
0
0
0
8,275
9,241
12,979
Niobrara
River
Lusk 847 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
11
92
265
479
404
167
822
826
602
626
620
642
746
605
556
498
776
442
0
6
12
0
0
0
0
0
0
3,181
3,329
2,687
Notes: 1Where more than one climate station is listed, the stations were weighted 50-50

Table 5
Estimated Actual Surface Water Depletions (Acre-Feet)

Source of
Supply
Climate
Stations1
Active
Irrigation
(Acres)
Hydrologic
Condition
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Little
Missouri
River
Colony,
Weston
9,799 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
2,456
2,128
3,101
3,491
3,795
4,837
4,062
4,443
4,030
5,273
4,480
4,061
5,137
4,190
3,341
5,258
4,254
3,239
288
331
412
0
0
0
0
0
0
25,965
23,622
23,021
Upper Belle
Fourche River
Gillette 3,312 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
229
316
690
936
1,147
1,375
1,550
1,492
1,518
1,891
1,543
1,381
1,864
1,569
1,116
1,762
1,386
1,029
14
41
32
0
0
0
0
0
0
8,264
7,494
7,142
Middle Belle
Fourche River
Moorcroft 9,011 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
414
437
866
1,873
2,485
4,607
3,495
4,313
4,239
4,600
4,031
3,522
4,904
4,513
3,268
5,154
4,213
2,860
70
76
63
0
0
0
0
0
0
20,510
20,066
19,425
Lower Belle
Fourche River
Colony 5,584 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
397
400
824
1,161
1,766
4,362
2,215
2,944
2,758
3,478
3,078
2,752
3,112
2,978
2,044
3,551
2,952
1,889
92
115
149
0
0
0
0
0
0
14,007
14,232
14,777
Redwater
Creek
Sundance 2,213 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
24
47
83
279
459
1,010
761
1,069
876
1,194
1,163
965
1,013
1,159
667
994
891
634
1
3
3
0
0
0
0
0
0
4,266
4,790
4,238
Upper Beaver
Creek
Upton 669 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
8
11
37
125
156
475
327
327
304
393
306
311
339
353
213
481
415
266
4
3
2
0
0
0
0
0
0
1,678
1,571
1,607
Middle Beaver
Creek
Newcastle,
Upton
6,000 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
49
108
369
1,105
1,448
4,307
3,197
3,277
2,971
3,630
2,944
2,913
2,856
3,217
1,926
4,424
3,851
2,410
20
13
13
0
0
0
0
0
0
15,280
14,858
14,908
Lower Beaver
Creek
Morrisey,
Newcastle
3,561 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
215
237
314
671
812
2,014
1,515
1,841
1,585
1,546
1,639
1,346
1,281
1,856
956
1,861
2,120
1,260
88
89
80
0
0
0
0
0
0
7,177
8,595
7,555
Northern
Tributaries to
Cheyenne
Morrisey 7,958 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
837
783
1,287
1,207
2,491
4,320
3,744
3,276
4,108
3,116
2,710
2,839
3,508
3,167
1,964
2,955
3,076
3,127
913
447
594
0
0
0
0
0
0
16,280
15,949
18,238
Southern
Tributaries to
Cheyenne
Redbird 12,736 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1,294
2,447
2,922
3,838
4,289
8,776
6,858
7,294
7,697
6,440
6,297
5,724
6,827
6,115
4,315
6,884
6,800
3,984
43
19
156
0
0
0
0
0
0
32,184
33,262
33,574
Lower
Cheyenne
River
Morrisey,
Redbird
2,602 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
231
220
379
364
794
1,511
1,235
1,116
1,400
1,046
913
962
1,161
1,073
651
985
1,027
1,023
250
123
163
0
0
0
0
0
0
5,273
5,266
6,089
Niobrara
River
Lusk 847 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
3
28
82
223
242
134
555
567
320
466
399
342
539
437
267
377
502
193
0
2
3
0
0
0
0
0
0
2,163
2,176
1,341
Notes: 1Where more than one climate station is listed, the stations were weighted 50-50


click to enlarge

ESTIMATED ACTUAL HISTORIC DEPLETIONS

The estimated actual depletions for wet, normal, and dry years are provided in Tables 6 and 8. The depletions summarized here represent the crop water consumption during the period of irrigation. It should be noted that depletions to the river system for any given month are calculated as diversions in that month less lagged return-flows which return back to the stream in that same month. These diversions minus return flows may, in fact, actually result in negative depletions (accretions) to the stream system in the post irrigation season months, when return flows arrive back into the system and diversions have ceased. The difference is typically small on an annual basis but is significant from month to month. The method which utilizes estimated actual diversions and subsequent return flows is used in the water availability models developed for this planning effort rather than the CIR based depletions reported here (Spreadsheet Model Development and Calibration, HKM, 2002).

Lacking diversion data for the lands served from ground water, the same methodology is applied to these lands. The estimated actual depletions for the lands supplied by ground water are provided on Tables 7 and 9. A GIS data theme of agricultural ground water wells with capacities greater than 49 gpm has been developed and is shown on Figure 2.

Table 6
Estimated Actual Surface Water Depletions (Acre-Feet)

Source of
Supply
Climate
Stations1
Active
Irrigation
(Acres)
Hydrologic
Condition
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Little
Missouri
River
Colony,
Weston
9,799 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
614
532
775
1,047
1,138
1,451
1,828
2,000
1,813
3,427
2,912
2,640
3,082
2,514
2,005
1,577
1,276
972
72
83
103
0
0
0
0
0
0
11,648
10,455
9,759
Upper Belle
Fourche River
Gillette 3,312 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
57
79
173
281
344
413
698
671
683
1,229
1,003
898
1,118
942
669
529
416
309
4
10
8
0
0
0
0
0
0
3,915
3,465
3,152
Middle Belle
Fourche River
Moorcroft 9,011 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
103
109
216
562
745
1,382
1,573
1,941
1,908
2,990
2,620
2,290
2,942
2,708
1,961
1,546
1,264
858
17
19
16
0
0
0
0
0
0
9,734
9,406
8,630
Lower Belle
Fourche River
Colony 5,584 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
99
100
206
348
530
1,309
997
1,325
1,241
2,261
2,001
1,789
1,867
1,787
1,226
1,065
886
567
23
29
37
0
0
0
0
0
0
6,661
6,656
6,374
Redwater
Creek
Sundance 2,213 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
6
12
21
84
138
303
342
481
394
776
756
627
608
696
400
298
267
190
0
1
1
0
0
0
0
0
0
2,115
2,350
1,937
Upper Beaver
Creek
Upton 669 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
2
3
9
38
47
142
147
147
137
256
199
202
203
212
128
144
124
80
1
1
1
0
0
0
0
0
0
791
733
698
Middle Beaver
Creek
Newcastle,
Upton
6,000 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
12
27
92
331
435
1,292
1,439
1,475
1,337
2,360
1,914
1,894
1,714
1,930
1,156
1,327
1,155
723
5
3
3
0
0
0
0
0
0
7,188
6,938
6,496
Lower Beaver
Creek
Morrisey,
Newcastle
3,561 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
54
59
79
201
244
604
682
828
713
1,005
1,065
875
768
1,114
574
558
636
378
22
22
20
0
0
0
0
0
0
3,291
3,969
3,242
Northern
Tributaries to
Cheyenne
Morrisey 7,958 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
209
196
322
362
747
1,296
1,685
1,474
1,848
2,025
1,762
1,845
2,105
1,900
1,178
886
923
938
228
112
148
0
0
0
0
0
0
7,501
7,113
7,577
Southern
Tributaries to
Cheyenne
Redbird 12,736 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
323
612
730
1,151
1,287
2,633
3,086
3,282
3,464
4,186
4,093
3,721
4,096
3,669
2,589
2,065
2,040
1,195
11
5
39
0
0
0
0
0
0
14,919
14,988
14,371
Lower
Cheyenne
River
Morrisey,
Redbird
2,602 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
58
55
95
109
238
453
556
502
630
680
594
625
697
644
391
295
308
307
63
31
41
0
0
0
0
0
0
2,458
2,372
2,542
Niobrara
River
Lusk 847 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1
7
20
67
73
40
250
255
144
303
259
222
323
262
160
113
151
58
0
0
1
0
0
0
0
0
0
1,057
1,007
646
Notes: 1Where more than one climate station is listed, the stations were weighted 50-50

Table 7
Estimated Actual Ground Water Depletions (Acre-Feet)

Source of
Supply
Climate
Stations1
Active
Irrigation
(Acres)
Hydrologic
Condition
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Little
Missouri
River
Colony,
Weston
0 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Upper Belle
Fourche River
Gillette 352 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
25
32
37
146
121
112
177
171
108
89
72
49
0
0
0
0
0
0
0
0
0
437
396
306
Middle Belle
Fourche River
Moorcroft 112 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2
5
10
11
38
33
30
51
50
34
28
23
15
0
0
0
0
0
0
0
0
0
123
117
91
Lower Belle
Fourche River
Colony 186 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
3
5
12
37
28
40
38
81
72
66
75
76
49
44
37
22
0
0
0
0
0
0
0
0
0
233
237
215
Redwater
Creek
Sundance 163 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
11
10
53
49
42
63
66
45
40
33
24
0
0
0
0
0
0
0
0
0
159
159
120
Upper Beaver
Creek
Upton 0 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Middle Beaver
Creek
Newcastle,
Upton
143 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
14
14
13
54
44
43
58
64
39
43
37
24
0
0
0
0
0
0
0
0
0
168
159
120
Lower Beaver
Creek
Morrisey,
Newcastle
0 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Northern
Tributaries to
Cheyenne
Morrisey 127 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
12
11
16
33
29
31
46
44
27
20
21
20
0
0
0
0
0
0
0
0
0
112
105
95
Southern
Tributaries to
Cheyenne
Redbird 387 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
1
6
11
21
69
72
93
102
146
145
135
161
161
102
84
83
46
0
0
0
0
0
0
0
0
0
474
505
461
Lower
Cheyenne
River
Morrisey,
Redbird
0 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Niobrara
River
Lusk 11,566 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1
29
207
687
948
615
3,397
3,650
2,064
4,528
3,880
3,351
5,105
4,271
2,527
1,797
2,407
898
0
1
1
0
0
0
0
0
0
15,515
15,185
9,663
Notes: 1Where more than one climate station is listed, the stations were weighted 50-50

Table 8
Estimated Actual Surface Water Depletions (Acre-Feet)

Source of
Supply
Active
Irrigation
(Acres)
Hydrologic
Condition
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Little
Missouri
River
9,799 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
614
532
775
1,047
1,138
1,451
1,828
2,000
1,813
3,427
2,912
2,640
3,082
2,514
2,005
1,577
1,276
972
72
83
103
0
0
0
0
0
0
11,648
10,455
9,759
Belle
Fourche
River
17,907 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
260
288
595
1,191
1,619
3,103
3,267
3,937
3,832
6,480
5,624
4,976
5,928
5,436
3,856
3,140
2,565
1,733
44
58
61
0
0
0
0
0
0
20,310
19,526
18,157
Redwater
Creek
2,213 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
6
12
21
84
138
303
342
481
394
776
756
627
608
696
400
298
267
190
0
1
1
0
0
0
0
0
0
2,115
2,350
1,937
Beaver
Creek
10,230 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
68
89
180
570
725
2,038
2,268
2,450
2,187
3,620
3,178
2,970
2,685
3,256
1,857
2,030
1,916
1,181
28
26
24
0
0
0
0
0
0
11,269
11,640
10,437
Cheyenne
River
23,295 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
590
862
1,147
1,623
2,272
4,382
5,327
5,259
5,942
6,892
6,448
6,192
6,898
6,213
4,158
3,247
3,271
2,440
302
147
228
0
0
0
0
0
0
24,878
24,473
24,489
Niobrara
River
847 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1
7
20
67
73
40
250
255
144
303
259
222
323
262
160
113
151
58
0
0
1
0
0
0
0
0
0
1,057
1,007
646

Table 9
Estimated Actual Ground Water Depletions (Acre-Feet)

Source of
Supply
Active
Irrigation
(Acres)
Hydrologic
Condition
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Little
Missouri
River
0 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
Belle
Fourche
River
650 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
3
6
12
39
58
81
86
265
227
207
304
297
191
161
132
86
0
0
0
0
0
0
0
0
0
793
750
612
Redwater
Creek
163 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
11
10
53
49
42
63
66
45
40
33
24
0
0
0
0
0
0
0
0
0
159
159
120
Beaver
Creek
143 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
14
14
13
54
44
43
58
64
39
43
37
24
0
0
0
0
0
0
0
0
0
168
159
120
Cheyenne
River
514 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
0
1
6
11
21
71
85
104
119
178
174
166
207
205
129
105
104
66
0
0
0
0
0
0
0
0
0
586
610
556
Niobrara
River
11,566 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1
29
207
687
948
615
3,397
3,650
2,064
4,528
3,880
3,351
5,105
4,271
2,527
1,797
2,407
898
0
1
1
0
0
0
0
0
0
15,515
15,185
9,663


click to enlarge

A total of 30,269 acres of irrigation served by spreader dikes or "kick-out" ditches were mapped in the planning area (Irrigation Classification S and H). These systems are typically located in the bottomlands of ephemeral tributaries and use the water to the extent it is available, whenever it is available. Depletions for these lands do not depend on operation of stream diversion works or pumps as do conventional irrigation systems and therefore are treated differently. Depletions for these lands are not constrained by the number of days of irrigation diversion but, rather, are based on the growing season as presented in Dr. Pochop's study (Pochop; et.al, October 1992). It is assumed that the actual annual water use for these lands is 40% of the theoretical maximum water use in dry years, 50% of theoretical maximum in normal years, and 60% in wet years.

FULL SUPPLY DIVERSION REQUIREMENTS

The results of the agricultural water use estimates are used, in part, as inputs to the water availability models prepared for this planning effort. The modeling is used to determine the availability of excess flows for future development and also as a means of determining where there are needs for supplemental water supplies under existing conditions. The need for these supplemental supplies should be consistent with irrigators' perceptions of those needs. HKM utilized the diversion records during non supply-limited conditions (wet years) in the Powder/Tongue River Basin planning area as a measure of the level of supply that irrigators have settled on, under existing conditions, as a balance between maximizing crop yields while conserving their limited resources. This is defined here as the "full supply diversion requirement". This level of supply may be defined by a number of conditions including how much money and effort the irrigator is willing to expend on repairing and maintaining diversion works or pumping facilities and managing on-farm irrigation. This level of supply is typically less than the theoretical maximum diversion requirement and this is especially true for relatively low-value forage crops.

The average proportion of historic diversions to theoretical maximum diversions during the period of irrigation in wet years for the Powder/Tongue River Basin planning area is 73 percent as shown in Table 3. The full supply diversion requirement for the Northeast Wyoming River Basins planning area is, therefore selected as 75 percent of the theoretical maximum (slightly higher than the wet year proportion) for each service area with it's unique combination of acreage, crops, and climate and for each hydrologic condition (wet, normal, and dry years).

The full supply diversion requirements are provided in Table 10 for wet, normal, and dry years.

Table 10
Full Supply Surface Water Diversion Requirements (Acre-Feet)

Source of
Supply
Climate
Stations1
Active
Irrigation
(Acres)
Hydrologic
Condition
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual
Little
Missouri
River
Colony,
Weston
9,799 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
3,232
3,314
5,980
4,499
5,536
7,688
4,963
6,217
7,087
6,288
6,360
7,142
6,170
5,769
6,025
6,249
6,029
5,966
370
515
790
0
0
0
0
0
0
31,771
33,740
40,678
Upper Belle
Fourche River
Gillette 3,312 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
334
530
1,400
1,271
1,602
1,793
1,835
1,910
2,464
2,122
2,041
2,240
2,126
1,945
1,912
1,963
1,827
1,852
19
69
64
0
0
0
0
0
0
9,671
9,925
11,725
Middle Belle
Fourche River
Moorcroft 9,011 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
805
895
1,950
2,820
3,237
4,756
3,963
4,943
6,235
4,786
4,888
5,179
5,241
4,937
5,252
5,294
5,076
4,990
113
156
146
0
0
0
0
0
0
23,023
24,132
28,508
Lower Belle
Fourche River
Colony 5,584 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
798
838
1,875
1,765
2,288
4,435
2,504
3,349
4,030
3,600
3,710
4,020
3,311
3,231
3,270
3,628
3,536
3,289
153
244
351
0
0
0
0
0
0
15,760
17,196
21,270
Redwater
Creek
Sundance 2,213 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
96
149
217
477
559
887
834
1,131
1,202
1,176
1,324
1,324
1,032
1,164
1,023
963
1,006
1,081
3
11
10
0
0
0
0
0
0
4,582
5,345
5,745
Upper Beaver
Creek
Upton 669 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
64
46
100
225
186
400
355
339
410
382
343
419
341
347
322
459
461
451
20
18
14
0
0
0
0
0
0
1,846
1,740
2,115
Middle Beaver
Creek
Newcastle,
Upton
6,000 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
695
551
1,038
2,023
1,714
3,572
3,458
3,371
3,979
3,505
3,278
3,900
2,862
3,132
2,903
4,196
4,252
4,075
162
146
127
0
0
0
0
0
0
16,901
16,445
19,594
Lower Beaver
Creek
Morrisey,
Newcastle
3,561 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
509
553
746
1,060
1,029
1,935
1,693
2,037
2,262
1,570
1,933
1,919
1,341
1,954
1,505
1,863
2,484
2,177
164
215
208
0
0
0
0
0
0
8,200
10,206
10,751
Northern
Tributaries to
Cheyenne
Morrisey 7,958 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1,181
1,282
2,570
1,613
3,525
5,933
4,472
4,295
6,810
3,555
3,655
4,705
4,057
4,036
3,413
3,349
4,134
5,662
1,221
729
1,174
0
0
0
0
0
0
19,448
21,656
30,267
Southern
Tributaries to
Cheyenne
Redbird 12,736 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
1,954
4,207
6,015
5,291
5,925
10,946
8,057
9,149
12,264
7,129
8,198
9,117
7,695
7,403
7,308
7,554
8,816
7,128
60
33
318
0
0
0
0
0
0
37,740
43,732
53,095
Lower
Cheyenne
River
Morrisey,
Redbird
2,602 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
346
376
777
500
1,100
1,906
1,454
1,407
2,242
1,162
1,194
1,540
1,313
1,307
1,106
1,085
1,338
1,832
346
209
331
0
0
0
0
0
0
6,207
6,931
9,734
Niobrara
River
Lusk 847 Wet
Normal
Dry
0
0
0
0
0
0
0
0
0
8
69
198
359
303
125
616
619
452
469
465
482
560
453
417
373
582
332
0
5
9
0
0
0
0
0
0
2,386
2,497
2,015
Notes: 1Where more than one climate station is listed, the stations were weighted 50-50

STOCK POND EVAPORATION

Evaporation from stock ponds is considered to be a relatively minor contributor to total water consumption in most river basins in the State. However, given the relative scarcity of surface water in the Northeast Wyoming River Basins planning area, together with the large number of stock ponds that exist, the accumulative evaporation loss from these ponds is relatively significant. HKM utilized two information bases to estimate evaporative loss from stock ponds:

  1. Digital base maps developed through the irrigated lands mapping work (Irrigated Lands Mapping and Water Rights Data, HKM, 2002).

  2. SEO database of permitted stock ponds as of December 2000
The digital base maps are a digital representation of the 1: 24,000 scale, United States Geological Society (USGS) 7 ½ minute quadrangle maps and show stock ponds to the extent that they have been mapped by the USGS. The spatial data layer that contains the stock pond polygons also contained the larger irrigation reservoirs as well as miscellaneous other spatial data such as gravel bars in rivers, abandoned ox-bow lakes, sewage ponds, natural marshes. HKM therefore pre-processed this spatial data set to remove this extraneous data prior to performing the analysis.

Stock ponds, as defined by the SEO, are limited to those impoundments with a total capacity of 20 acre- feet or less. Further, the Belle Fourche River Compact permits Wyoming's unlimited use of stock water reservoirs not exceeding 20 acre-feet in capacity. This 20 acre-foot capacity then defines the upper limit of the reservoirs that are the target of this analysis. Unfortunately, the mapped ponds provide information regarding the maximum surface area but no information regarding the capacity of each pond. The SEO database of permitted stock ponds, however, provides capacity information, albeit, only for those stock ponds which were permitted as of December 2000. There were a total of 5,093 permitted stock ponds in the Northeast Wyoming River Basins planning area as of this date.

The SEO stock pond permit data provides the location of the ponds to the nearest quarter-quarter section. A GIS data theme of permitted stock ponds was created utilizing this information, positioning the permit points in the center of the designated quarter-quarter section. The permitted stock ponds are shown on Figure 3. The inventory of mapped stock ponds can only be performed for those areas of the planning area where digital base maps were acquired for this study. The extent of the digital base map coverage is shown in the Irrigated Lands Mapping and Water Rights Data memorandum and covers roughly 74% of the total geographic area (HKM, 2002). Of the 5,093 permits, 4,034 fall within areas where digital base maps are available. HKM spatially joined the stock pond permit points with the mapped ponds within a quarter mile radius of the respective points. In many cases, there were no mapped ponds within a quarter mile of the permit points. Conversely, in many cases there were multiple mapped ponds within a quarter mile of the respective permit points and no way of knowing which one the permit pertained to. In total 1,442 permit points could conclusively be tied to stock ponds shown on the digital base maps. With this information, the permitted capacity was related to the mapped surface area of these 1,442 ponds in order to determine the typical maximum surface area of stock ponds as defined for this analysis (20 acre-feet and less). Only those ponds on the digital base maps with maximum surface areas of 6 acres or less were considered to be stock ponds as defined here. A GIS data theme of mapped stock ponds was created as illustrated on Figure 4.


click to enlarge


click to enlarge

The net depth of reservoir evaporation from the stock ponds was determined by reducing the gross monthly lake evaporation from the Lewis study (Lewis, 1978) by the monthly precipitation from the Parameter-Elevation Regressions on Independent Slopes Model (PRISM) (Daly and Taylor, 1998). The GIS data theme of gross reservoir evaporation is illustrated on Figure 5. The GIS data theme of annual precipitation from PRISM is shown on Figure 6. The net depth of evaporation was then applied to the reservoir surface areas determined from the mapping to determine the total evaporation volume. The maximum reservoir surface areas were, however, first reduced to reflect the fact that the stock ponds are typically only full for a short time each year. Based on input from the Basin Advisory Group, it is assumed that the typical stock pond is empty on May 1st, is full on June 1st, and gradually empties until it's dry on August 1st. The total volume of stock pond evaporation for the portion of the basin covered by digital base maps is estimated at 4,640 acre-feet. Extrapolating out for the remaining 26% of the planning area not covered by digital base maps, it is estimated that the total volume of stock pond evaporation for the Northeast Wyoming River Basins planning area is 6,300 acre-feet from 16,600 stock ponds.


click to enlarge


click to enlarge

REFERENCES

Cuenca, Richard H., 1989. Irrigation System Design . An Engineering Approach, Prentice-Hall, Inc., Englewood Cliffs, New Jersey

Daly, Chris and George Taylor, April 1998. Wyoming Average Monthly or Annual Precipitation, 1961- 1990, http://www.ocs.orst.edu/prism/, Portland, Oregon [new link 10/2009 HERE]

Dastane, N., 1974. Effective Rainfall in Irrigated Agriculture, Irrigation and Drainage Paper No. 25, FAO, United Nations

HKM Engineering Inc., 2002. Irrigated Crops, Technical Memorandum, Northeast Wyoming River Basins Plan. Billings, Montana

HKM Engineering Inc., 2002. Irrigated Crops, Technical Memorandum, Powder/Tongue River Basin Plan. Billings, Montana

HKM Engineering Inc., 2002. Irrigation Diversion Operation and Description, Technical Memorandum, Northeast Wyoming River Basins Plan. Billings, Montana

HKM Engineering Inc., 2002. Irrigation Diversion Operation and Description, Technical Memorandum, Powder/Tongue River Basin Plan. Billings, Montana

HKM Engineering Inc., 2002. Irrigated Lands Mapping and Water Rights Data, Technical Memorandum, Northeast Wyoming River Basins Plan. Billings, Montana

HKM Engineering Inc., 2002. Irrigated Lands Mapping and Water Rights Data, Technical Memorandum, Powder/Tongue River Basin Plan. Billings, Montana

HKM Engineering Inc., 2002. Spreadsheet Model Development and Calibration, Technical Memorandum, Northeast Wyoming River Basins Plan. Billings, Montana

HKM Engineering Inc., 2002. Storage Operation and Description, Technical Memorandum, Powder/ Tongue River Basin Plan. Billings, Montana

HKM Engineering Inc., 2002. Surface Water Hydrology, Technical Memorandum, Northeast Wyoming River Basins Plan. Billings, Montana

HKM Engineering Inc., 2002. Surface Water Hydrology, Technical Memorandum, Powder/Tongue River Basin Plan. Billings, Montana

Lewis, Larry Eugene, May 1978. Development of an Evaporation Map for the State of Wyoming for Purposes of Estimating Evaporation and Evapotranspiration, University of Wyoming master's thesis, Department of Civil and Architectural Engineering and the Graduate School, Laramie, Wyoming

Pochop, Larry, Travis Teegarden, Greg Kerr, Ronald Delaney and Victor Hasfurther, October 1992. Consumptive Use and Consumptive Irrigation Requirements . Wyoming, WWRC Publication #92-06. Laramie, Wyoming

Wyoming State Engineer's Office, April 1972. Wyoming Water Planning Program, Report 10, Water & Related Land Resources of Northeastern Wyoming. Cheyenne, Wyoming