Bear River Basin Water Plan
Technical Memoranda

1.0 Introduction

The Wyoming Water Development Commission has undertaken statewide water basin planning efforts in selected river basins. The purpose of the statewide planning process is to provide decision makers with current, defensible data to allow them to manage water resources for the benefit of all the state's citizens. The Bear River, because of its interstate nature, has been selected as an initial basin to catalogue its water resources.

The Bear River Spreadsheet Model is a complex spreadsheet which incorporates multiple diversions, reservoirs, gaging stations, and other water resources within the Bear River located in the extreme southwest corner of Wyoming. The model was developed following several months of effort and coordination with various state and local agencies and water officials. The purpose of the model is to provide a planning tool to the State of Wyoming for use in determining those river reaches in which flows may be available to Wyoming water users for future development.

1.1 Model Overview

Individual spreadsheet models were developed which reflect each of three hydrologic conditions: dry, normal, and wet year water supply. Each model relies on historical data from the 1971 to 1998 study period to estimate the hydrologic conditions, as discussed in the Task "A Memorandum, ASurface Water Data Collection and Study Period Selection." Such factors as streamflow, diversions, and irrigation returns were analyzed to determine the type of hydrologic condition and are the basic input data to the model. The model does not explicitly account for water rights, appropriations, or compact allocations nor operate the river basin based on these legal constraints. It is assumed that the historic data reflect effects of any limitations which may have been placed upon water users by water rights restrictions.

To mathematically represent the Bear River system, the river system was divided into twelve reaches based primarily upon the location of USGS gaging stations. Other key locations, such as reservoirs or confluences with major tributaries, were also used to determine the extent of reaches. Each reach was then sub-divided by identifying a series of individual nodes representing locations where diversions occur, basin imports are added, tributaries converge, or other significant water resources features are located. Figure 1 presents a node diagram of the model developed for the Bear River.

click to enlarge

At each node, a water budget computation is completed to determine the amount of water that flows downstream out of the node. Total flow into the node and diversions or other losses from the node are calculated. At non-storage nodes, the difference between inflow, including return flows, and diversions 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 are evaluated. Also at storage nodes, any uncontrolled spill which occurs is added to the scheduled release to get total outflow. Mass balance, or water budget calculations, are repeated for all nodes in a reach, with the outflow of the last node being the inflow to the top node in the next reach.

For each reach, ungaged stream gains (e.g., ungaged tributaries, groundwater inflow, and return flows from unspecified diversions) and losses (e.g. seepage, evaporation, and unspecified diversions) are computed as the difference between average historical gage flows. Stream gains are input at the top of a reach to be available for diversion throughout the reach and losses are subtracted at the bottom of each reach.

Model output includes the target and actual diversions at each of the diversion points, streamflow at each of the Bear River Basin nodes, and evaluation of water emergency conditions as defined by the Bear River Compact. 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. Complete model input and output for each of the dry, normal, and wet year conditions are included in Appendices A, B, and C, respectively.

1.2 Model Development

The model was developed using Microsoft® Excel 2000. It consists of a series of three-dimensional spreadsheets (i.e., workbooks) which can be thought of as a series of water commissioner's worksheets; each page or worksheet contains the data or logic necessary to compute a separate task. Each entry (i.e., cell) in a workbook contains data or formulas which reference other cells on the same page or anywhere within the workbook. The function of each page (i.e., worksheet) is discussed in detail in subsequent sections of this memorandum.

Within the workbooks are macros written in Microsoft® Excel Visual Basic programming language. The primary function of the macros is to facilitate navigation within the workbook. There are no macros which complete computation of any formulas or results. In other words, whenever a number is input into any cell anywhere in the workbook, the entire workbook is recalculated and updated automatically.

The model was developed with the novice Excel user in mind. Every effort has been taken to lead the User through the model with interactive buttons and mouse-driven options. However, an elementary level of expertise in spreadsheet usage and programming is assumed. This document will not provide instructions in the use of Excel for this spreadsheet. Appendix G is provided as a guide to installing the model. Appendix H is provided as a programmer=s guide to assist in editing the Excel code and for future modifications to the model. In the next chapter, information and instructions on the use of the model are detailed.

2.0 Model Structure and Components

Each of the three hydrologically-conditioned Bear River Models is a three-dimensional spreadsheet (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:

1. Navigation Worksheets: these GUIs contain buttons used to move within the workbook;

2. Input Worksheets: facilitate input of raw data (USGS Gage data, Diversion Data, etc.);

3. Computation Worksheets: compute various components of the model (reservoir evaporation, irrigation return flows, etc.);

4. Reach/Node Worksheets: calculate node by node computations of the water budget; and

5. Results Worksheets: tabulate and present the model output.

In this chapter, each component of the Bear River Model is discussed in greater detail. A general discussion of each component includes a brief overview of the function. The discussion of each component also generally includes two sections:

1. Engineering Notes: Detailed discussion of methodologies, assumptions, and sources used in the development of that component; and

2. User Notes: "How to" instructions for model Users.

Programmer Notes, which are instructions and suggestions for programmers modifying the model, are included in Appendix H. These will assist state and local officials with any modifications of this model to analyze changed conditions or other applications in the Bear River Basin. Additionally, since this model may be a basis for developing spreadsheet models for other basins, this will serve as a guide for other consulting groups.

2.1 The Navigation Worksheets

A Graphical User Interface (GUI) was developed to assist the User in navigating around the spreadsheets. The initial navigation worksheet or GUI provides the User with an interactive interface to the Bear River Model. The GUI provides a brief tutorial, help screens, and information regarding the current model version (Figure 2). It is initialized by opening the Bear River Model file from within Excel. From the GUI, the User may select the appropriate model to evaluate the desired hydrologic condition (i.e., average dry, normal, or wet year).

Figure 2. Graphical User's Interface (GUI) Main Page

User Notes:

Upon opening the Bear River Model file, the User is presented with several options:

1. HELP	Provides a text file containing instructions and background information,
2. Dry Year Model:	Open the Dry Year Model workbook,
3. Normal Year Model:	Open the Normal Year Model workbook,
4. Wet Year Model:	Open the Wet Year Model workbook,
5. About Bear River Model:	Obtain information pertaining to the current version of the model,
6. Tutorial	Open a brief tutorial of the Bear River Model,
7. Close the Bear River Model	Close any open workbooks.

2.1.1 The Central Navigation Worksheet

The Central Navigation Worksheet is the "heart" of the model. From here, the User can "jump" to and from any worksheet in the model (Figure 3).

Figure 3. Central Navigation Worksheet

User Notes:

This is the first worksheet the User will see upon selection of a hydrologic condition from the GUI. From this worksheet, the User can access any other worksheet in the model. A series of buttons can be used to "jump" directly to any other location in the workbook. Figure 3 displays the Central Navigation Worksheet from the Normal Year Model.

The User can go to specific reaches by selecting the desired reach from the pull-down menu. When a reach is selected, a table is presented which tabulates all of the nodes in that reach and a brief description of it.

User Notes:

The Basin Map Worksheet (Figure 4) provides a simple "stick diagram" of the basin, which is a simplified version of Figure 1. This interactive screen allows the User to visually select a reach to which to "jump". To select a reach, simply click on any reach arrow or its name.

Figure 4. Bear River Basin Diagram (GUI)

User Notes:

The Results Navigator (Figure 5) facilitates the selection of any of the following output tabulations:

• Estimated Outflow from each Node
• Estimated Outflow from each Reach
• Estimated Diversions at each Diversion Node
• Estimated Total Diversions from each Reach
• Compact Allocations: Upper Division
• Compact Allocations: Central Division

Figure 5. Bear River Basin Results Navigator Worksheet (GUI)

2.2 The Input Worksheets

2.2.1 Master List of Nodes: Matching Number and Name

The model is structured around nodes at which mass balance calculations are made and reaches that connect the nodes. Nodes are points on the river that represent such water resources features as USGS Gage locations, diversion headgates, confluences of the Bear River and its tributaries, or reservoirs. There are a total of 64 nodes in the model; 10 USGS gages, 36 named or key diversion points, 10 aggregated diversion points, and two fully modeled reservoirs (i.e., storage modeled and evaporation included). Also included are five node points, which are confluences of tributaries with the mainstem and Stewart Dam, which was modeled as a river node point but not as a reservoir.

Engineering Notes:

The delineation of a river basin by reaches and nodes is more an art than a science. The choice of nodes must consider the objectives of the study and the available data. It also must contain all the water resources feature that govern the operation of the basin. The analysis of results and their adequacy in addressing the objectives of the study are based on the input data and the configuration of the river basin by the computer model.

User Notes:

This worksheet presents a master list of all nodes included in the Bear River Model (Table 1). The list allows the User to view a simple, comprehensive listing of all nodes within the model, organized by reach and node number. This master list governs naming and numbering conventions on many worksheets, so changing the list must be carefully done and checked. Many of the calculations within the spreadsheet are dependent on the proper correlation of node names and numbers.

Note that the numbering convention used for node identification includes the reach number and the location of the node within it. For example, Node 10.05 is the fifth node in Reach 10. There are exceptions to this rule where a node has been added between existing nodes. In these cases, the numbering is not sequential, but the numbering system does not govern the flow connections in the system.

Table 1. Master List of Node Numbers and their Names

Node 1.00	USGS 10011500: Bear River near UT-WY State Line
Node 1.01	Lannon & Lone Mountain
Node 1.02	Hilliard West Side
Node 1.03	Bear Canal
Node 1.04	Crown & Pine Grove
Node 1.05	McGraw & Big Bend
Node 1.06	Lewis
Node 1.07	Meyers No. 2
Node 1.08	Meyers No. 1
Node 1.09	Meyers Irrigation
Node 1.10	Evanston Pipeline
Node 1.11	Booth
Node 1.12	Anel
Node 1.13	Evanston Water Supply
Node 1.15	AggDiv BR-1
Node 2.00	USGS 10015700: Sulphur Cr. ab Res.BL.La Chapelle Cr.Nr. Evanston,WY
Node 2.01	AggDiv SC-1/Broadbent
Node 2.02	Sulphur Creek Reservoir
Node 2.03	AggDiv SC-2
Node 3.00	Confluence Sulphur Creek / Bear River
Node 3.01	Evanston Water Ditch
Node 3.02	Rocky Mtn & Blyth
Node 4.00	USGS 10016900: Bear R. at Evanston, WY
Node 4.01	John Simms
Node 4.02	S P Ramsey
Node 4.03	AggDiv Br-2
Node 5.00	Confluence Yellow Creek / Bear River
Node 5.01	Chapman Canal
Node 5.02	Morris Bros (Lower)
Node 5.03	AggDiv BR-3
Node 5.04	Tunnel
Node 6.00	USGS 10020100: Bear R. ab Res. near Woodruff, UT
Node 6.01	Woodruff Narrows Reservoir
Node 7.00	USGS 10020300: Bear R. bel Res. near Woodruff, UT
Node 7.01	Francis Lee
Node 7.02	Bear River Canal
Node 7.03	Aggregate Utah Diversions
Node 8.00	USGS 10026500: Bear R. near Randolph, UT
Node 8.01	Pixley Dam
Node 8.02	BQ Dam
Node 9.00	USGS 10028500: Bear R. bel Pixley Dam, near Cokeville, WY
Node 9.01	Confluence Smiths Fork / Bear
Node 9.02	AggDiv BR-4
Node 10.01	USGS 10032000: Smiths Fork near Border, WY
Node 10.02	Button Flat
Node 10.03	Emelle
Node 10.04	Cooper
Node 10.05	Covey
Node 10.06	VH Canal
Node 10.07	Goodell
Node 10.08	Whites Water
Node 10.09	S Branch Irrigating
Node 10.10	AggDiv SF-1
Node 11.00	USGS 10038000: Bear R. bel Smiths Fork, near Cokeville, WY
Node 11.01	AggDiv BR-5
Node 11.02	Alonzo F. Sights
Node 11.03	Oscar E. Snyder
Node 11.04	Cook Brothers
Node 12.00	USGS 10039500: Bear R. at Border, WY
Node 12.01	Confluence Thomas Fork
Node 12.02	Aggregate Idaho Diversions
Node 12.03	Rainbow Inlet
Node 12.04	Stewart Dam

Monthly stream gage data were obtained from the USGS for each of the stream gages used in the model. Several of the gages contained incomplete records or missing data. Linear regression techniques were used to estimate missing values. A detailed discussion of this process is provided in the Task 3A Memorandum, Surface Water Data Collection and Study Period Selection.

A 1971 through 1998 study period was selected based largely upon review of the available data, the objectives of the model, and the historical development of the basin. Historic data were available at many of the USGS gaging stations for periods extending back to the early 1900's, however, measurement records were available at many of the key diversions in the Upper Division of the Bear River beginning in 1971.

Determination of dry, normal, and wet years was accomplished by plotting graphs of the ranked total annual streamflow at each gage. Based upon a combination of using natural breaks in the measured data and use of simple statistics, that is, the upper and lower 20% of the data; dry, normal, and wet years were selected for each gage. Average monthly values for each hydrologic condition were then computed at each gage as the basic streamflow input to the model.

Engineering Notes:

For a detailed discussion of the data filling and analysis associated with the USGS gaging data, see the Bear River Planning Study, Task 3A Memorandum. The analysis of Task 3A was based on a water year period. Because of return flow conditions in the development of the spreadsheet model, a calendar year basis for all data was selected. An analysis of the dry, normal, and wet year hydrologic condition was performed on the calendar year data to insure that dry years remain dry years, and similarly for the other two conditions. This was the case and, hence, although the annual volumes at the gage points changed slightly (less than 3 percent change in the three months as a percent of the annual total), the annual flows on a calendar year basis are used in the model.

Table 2 presents a summary of this effort and the determination of hydrologic conditions for each year of the study period. Appendix D includes the USGS data for the period of record at each gage. Average monthly values for each hydrologic condition were then computed at each gage as the basic streamflow input to the model (Table 3).

Table 2. Characterization of Wet, Normal, and Dry Years for Bear River Model Index Gages and Diversion Data Analysis

Table 3. Summary of average Dry, Normal, and Wet Year Streamflow at USGS Gaging Stations

User Notes:

The Gaging Data Table presents the average historic gaging data for each hydrologic condition used in the model. Only the data pertaining to the hydrologic condition being modeled are included in each respective model. These data represent the discharge which can be expected to occur each month in an average dry, normal, or wet year at all the gages used in the model.

2.2.3 Diversion Data

The Bear River Commission publishes diversion records in each of its Biennial Reports. These records were compiled to form the basis of diversion data input to the model. A complete record of diversions exists for the entire basin for the study period of 1971 through 1998. Provisional diversion data reflecting recent years (1996 through 1998) were obtained from the Wyoming State Engineers Office and directly from the Bear River Commission. Following completion of the model, the Bear River Commission published the 1997-1998 Biennial Report which included finalized diversion data for that period. These data were compared to the provisional data and no significant differences were observed.

Estimates of monthly diversions at each of 36 key specific diversions (see Appendix E) were computed for each of the three hydrologic conditions based upon the annual condition presented in Table 2. Key diversions were defined as those locations where greater than 10 cfs are diverted from the river. Eight aggregated diversions for all other diversions in Wyoming were added to complete the water balance for the basin (Appendix F). Diversions within Utah and Idaho were aggregated and modeled as single nodes. All diversions that are specified in the Bear River Compact are included, either explicitly in the model or in the Results Worksheets as data inputs (Table 4).

Table 4. Summary of Average Dry, Normal, and Wet Year Diversion Data

Engineering Notes:

The following sections summarize the sources of data for each division.

Upper Utah Section - Upper Division

• 1971-1998 data were obtained from tables published in the Bear River Commission Reports. Note that diversion records for the Hatch diversion began in 1992. These diversions are not explicitly modeled; however, their annual average totals are included in the Compact Allocation Worksheet in the results.

Wyoming Section - Upper Division

• 1971-1996 data were obtained from tables published in the Bear River Commission Reports.

• 1997-1998 data were obtained from preliminary diversion records provided by Jade Henderson, State Engineer's Cokeville Office. At the time that these data were provided, there was not yet a published Biennial Report for the period. In late April, 2000, the Bear River Commission published the 1997-1998 Biennial Report. Diversion records from these reports were spot checked against the preliminary data. This check resulted in no significant changes between the preliminary data and the published data.

Lower Utah Section - Upper Division

• 1971-1996 data were obtained from tables published in the Bear River Commission Reports.

• 1997-1999 date were obtained from preliminary diversion records provided by Don Barnett, Bear River Commission Office. At the time that these data were provide, Biennial Reports were not yet available for this period. In late April, 2000, the Bear River Commission published the 1997-1998 Biennial Report. Diversion records from these reports were spot checked against the preliminary data. This check resulted in no significant changes between the preliminary data and the published data.

Wyoming Section - Lower Division

• 1971-1996 data were obtained from tables published in the Bear River Commission Reports.

• 1997-1998 data were obtained from preliminary diversion records provided by Jade Henderson, State Engineer's Cokeville Office. At the time that these data were provided, there was not yet a published Biennial Report for the period. In late April, 2000, the Bear River Commission published the 1997-1998 Biennial Report. Diversion records from these reports were spot checked against the preliminary data. This check resulted in no significant changes between the preliminary data and the published data.

Wyoming Section - Central Division

• 1971-1996 date were obtained from tables published in the Bear River Commission Reports.

• 1997-1999 data were obtained from preliminary diversion records provided by Jade Henderson, State Engineer's Cokeville Office. At the time that these data were provided, Biennial Reports for this period were not yet available. In late April, 2000, the Bear River Commission published the 1997-1998 Biennial Report. Diversion records from these reports were spot checked against the preliminary data. This check resulted in no significant changes between the preliminary data and the published data.

Idaho Section - Central Division

• 1971-1996 data were obtained from tables published in the Bear River Commission Reports.
• 1997-1999 data were obtained from preliminary diversion records provided by Don Barnett, Bear River Commission Office. At the time that these data were provided, Biennial Reports for this period were not yet available. In late April, 2000, the Bear River Commission published the 1997-1998 Biennial Report. Diversion records from these reports were spot checked against the preliminary data. This check resulted in no significant changes between the preliminary data and the published data.

Bear River below Stewart Dam

• 1970-1999 data were provided by the PacifiCorp Office in Salt Lake City. The data were provided by Scott Johnson from that office. Records for the flow in the Bear River below Stewart Dam are published in the Bear River Commission Biennial Report only for the summer months. Since year-round data at this location was required for the model, PacifiCorp was contacted in order to obtain winter data at this gage. Although the summer records published in the Biennial Report varied slightly from those records provided by PacifiCorp, PacifiCorp's numbers for both summer and winter flows were used to keep consistency in the data source.

Rainbow Inlet

• 1971-1998 Data is from tables published in the Bear River Commission Reports.

Based upon the determination of hydrologic condition at each USGS gaging station conducted during Task 3A of the Bear River Planning Study, overall basin conditions were estimated (Table 2). Examination of Table 2 reveals that in general, the hydrologic conditions were very consistent throughout the basin. A row summarizing basin-wide hydrologic conditions for the Bear River Basin appears at the bottom of the table. From this selection of hydrologic year type, average monthly diversions for each of the three hydrologic conditions were determined.

Average monthly diversion data were computed based upon the basin-wide conditions (Appendix E). Average dry year diversions represent the average of diversions recorded during the six dry years (1977, 1979, 1988, 1990, 1992, and 1994), average normal year diversions represent the average of diversions during the nineteen normal years (1971-1976, 1978, 1980-1982, 1985, 1987, 1989, 1991, 1993, and 1995-1998), and average wet year diversions represent the average of diversions during the three wet years (1983, 1984, and 1986).

User Notes:

This worksheet provides a summary of the diversions which can be expected to occur at each node during a typical dry, normal, or wet year. This worksheet is a means of providing input data to the model; there are no computations conducted within it. Note that all nodes are listed in the table, even if no diversions occur at them. At the top of the worksheet are buttons which also take the User to a table summarizing the total monthly diversions in each reach.

The Broadbent Supply Ditch imports water from the Green River Basin. In 1999, it was fitted with a recorder and telemetry system which improved the ability to document this import. According to the 1999 Biennial Report, 24.8 acre-feet were imported for the period July 31 to the end of September.

Engineering Notes:

Average monthly historic data are lacking for the Broadbent Ditch because it was only recently equipped with gaging equipment. Based upon the 1999 Biennial Report, 24.8 acre- feet were imported over a 62 day period. This converts to an average of 0.2 cfs or an average of approximately 12 acre-feet per month. This value was used as the average monthly import for the Broadbent Ditch during the irrigation season in each hydrologic condition.

User Notes:

The Imports / Exports Table summarizes the monthly imports to or exports from other basins. In the Bear River Model, the only imports incorporated are those associated with the Broadbent Supply Ditch. There are no basin exports incorporated herein, although that capability exists at all nodes.

The spreadsheet model determines the water budget at node points along the river, reflecting inflows from gaged and ungaged tributaries and diversions from delivery points. The historic or estimated river headgate diversions are the demands that drive the model. The consumptive use portion of these diversions must be estimated along with the return flows. These return flows eventually return to the stream system and are available for future diversions.

2.3.1 Return Flows

The unused portion of a headgate diversion either returns to the river as surface runoff during the month it is diverted, or "deep percolates" into the alluvial aquifer. The deep percolation portion returns to the river through the aquifer but generally lags the time of diversion by several months, or even years. It is important for the model to simulate both the percent of headgate diversions that return to the river, and the timing of which this unused portion returns. In the Bear River Basin, water from the river is reused many times from the headwaters to the Great Salt Lake.

Diversion efficiency is the common measure of the portion of headgate diversion that is consumed, and therefore not returned to the river. Diversion efficiency for municipal and industrial use is the percent of headgate diversion that makes it to the treatment plant or industrial site. The remaining percent is lost during conveyance, and returns to the river as surface runoff or deep percolation. Diversions for agricultural use experience both conveyance losses and application losses, and both these loss percentages return to the river as surface runoff or deep percolation. Additional discussion of the consumptive use analysis and return flow study is contained in Tasks 2A, 2B, and 2C Memorandum, Bear River Planning Study.

Engineering Notes:

Table 5 shows the conveyance efficiencies estimated for the key ditch systems represented in the modeling effort for the upper division. The upper division aggregate ditch systems were assigned a conveyance efficiency of 65 percent, because they represent smaller ditches generally irrigating lands close to the river. Table 6 shows the conveyance efficiencies estimated for the key ditch systems represented in the modeling effort for the central division. The central division aggregate ditch systems were assigned a conveyance efficiency of 65 percent, again because they represent smaller ditches generally irrigating lands close to the river.

In addition to conveyance efficiencies, Table 5 shows the suggested application efficiency for the key ditch systems in the upper division. Because lands in the upper division are flood irrigated, the application efficiencies are all 55 percent. An application efficiency of 55 percent is also used for aggregated ditch systems. Table 6 shows the suggested application efficiency for the key ditch systems in the central division. An application efficiency of 65 percent was used for aggregated ditch systems in the central division, which represents an average of key ditch system efficiencies.

The model uses a diversion efficiency that represents the actual amount of headgate diversion used to satisfy crop consumptive use demands. It is calculated as the product of conveyance efficiency and application efficiency. The diversion efficiency is also provided in Tables 5 and 6.

Table 5. Upper Division Diversion Efficiencies

Model Node ID	Diversion Name	Converance Efficiency	Application Efficiency	Diversion Efficiency	Irrigation Methods
1.14	Hilliard East Fork	40%	55%	22%	100% Flood
1.01	Lannon and Lone Mountain	45%	55%	25%	100% Flood
1.02	Hilliard West Side	40%	55%	22%	100% Flood
1.03	Bear Canal	40%	55%	22%	100% Flood
1.04	Crown and Pine Grove	50%	55%	27%	100% Flood
1.05	McGraw (and Big Ben)	55%	55%	30%	100% Flood
1.06	Lewis	55%	55%	30%	100% Flood
1.07	Myers No 2	50%	55%	27%	100% Flood
1.08	Myers No 1	50%	55%	27%	100% Flood
1.09	Myers Irrigation	55%	55%	30%	100% Flood
1.11	Booth	50%	55%	27%	100% Flood
1.12	Anel	55%	55%	30%	100% Flood
1.13	Evanston Water Supply	50%	55%	27%	100% Flood
3.01	Evanston Water Ditch	65%	55%	36%	100% Flood
3.02	Rocky Mountain Blythe	65%	55%	36%	100% Flood
4.01	John Simms	65%	55%	36%	100% Flood
4.02	SP Ramsey	60%	55%	33%	100% Flood
5.01	Chapman (Wyoming portion)	50%	55%	27%	100% Flood
5.02	Morris Brothers	65%	55%	36%	100% Flood
5.03	Tunnel	65%	55%	36%	100% Flood
7.01	Francis Lee	60%	55%	33%	100% Flood
7.02	Bear River Canal	60%	55%	33%	100% Flood
Varies	Aggregate Systems	65%	55%	36%	100% Flood

Table 6. Central Division Diversion Efficiencies

Model Node ID	Diversion Name	Converance Efficiency	Application Efficiency	Diversion Efficiency	Irrigation Methods
7.03	Utah Aggregate Ditches	45%	65%	30%	67% Flood 33% Center Pivot Sprinkler
8.01	Pixley Dam	55%	60%	33%	90% Flood 10% Center Pivot Sprinkler
10.02	Button Flax	65%	55%	36%	100% Flood
10.03	Emelle	65%	55%	36%	100% Flood
10.04	Cooper	65%	55%	36%	100% Flood
10.05	Covey	45%	65%	30%	70% Flood 30% Center Pivot Sprinkler
10.06	VH Canal	55%	85%	47%	100% Center Pivot Sprinkler
10.07	Goodell	55%	85%	47%	100% Center Pivot Sprinkler
10.08	Whites Water	60%	65%	40%	60% Flood 40% Center Pivot Sprinkler
10.09	S. Branch Irrigation	60%	70%	42%	40% Flood 60% Center Pivot Sprinkler
11.01	Alonzo F. Sights	65%	65%	42%	60% Flood 40% Center Pivot Sprinkler
11.02	Oscar E. Snyder	65%	55%	36%	100% Flood
11.03	Cook Brothers	65%	55%	36%	100% Flood
Varies	Aggregates Systems	65%	65%	42%	67% Flood 33% Center Pivot Sprinkler

User Notes:

This worksheet computes the return flows from irrigation diversions, mainly. For every node, the return flow is computed based upon estimates of consumptive use associated with the crops irrigated, the extent and location of the irrigated acreage, and canal losses. For clarification, all cells which can be modified by the User are highlighted in yellow. The features of this worksheet are discussed in the following sections. Figure 6 displays an example table from the Return Flows worksheet.

Figure 6. Example Return Flows Node Table

Total Diversions

These values are retrieved automatically from the Diversion Data tables.

Efficiency Pattern

The model applies one of 17 pre-determined irrigation efficiency patterns to the water diverted at each node. The efficiency patterns represent that portion of the diversion which is lost to the system as a consumption. The remainder are losses, e.g., conveyance and on-farm efficiency losses (e.g., flood vs sprinkler irrigation efficiency), which are returned to the system at other river points. For example, an efficiency pattern of 25 means that 75% of the water diverted eventually returns to the river either by surface or subsurface flow and that 25% is consumed. These patterns are included on the Options Tables worksheet of the model. By entering the number associated with a pattern in this cell, the efficiency pattern is applied.

Total Irrigation Returns

These data are computed by multiplying the Total Diversions by the selected Efficiency Pattern. For example, if a month shows a Total Diversion of 883 acre-feet and an Efficiency Pattern of 25 is selected, the Total Irrigation Returns from that diversion will be 662 acre-feet (883 x (1.0-.25) = 662) distributed in a temporal pattern as specified by the Return Pattern. It is assumed that there is not sufficient variation in the monthly efficiency to justify a monthly- varying pattern.

TO and Percent

This feature allows the User to define the node in the model where irrigation returns will return. Return locations were determined based upon field inspection, local knowledge, and/or aerial photographs. By entering the node number in the TO box, and the relative percentage of the Total Irrigation Returns that are expected to return to that node, the Total Irrigation Returns are distributed accordingly. Note that the percentages entered at each node must total 100% or an error message will appear warning the User that all returns have not been accounted.

Return Pattern

The Return Pattern feature allows the User to select between four different temporal patterns representing the lagged time effect of irrigation returns to the river. The four Return Patterns available are displayed in the Irrigation Return Lags section of the Options Table. Not all of the water diverted at a node returns to the river in the same month. The lags between the month in which a diversion occurs and the month the irrigation returns actually arrive in the river are estimated.

The Return Pattern feature first directs the model to account for that portion of irrigation returns occurring in the same month as the diversion. It then directs the model to add returns lagged from previous months. In this model, it was assumed that all irrigation returns will occur during the month it is diverted and within three additional months.

Irrigation Returns: Node Totals Table

This table collects all of the irrigation returns that have been sent to each Node and provides their sum. It is accessed via the "View 'Node Totals' Summary Table" button located at the top of the worksheet.

Irrigation Returns: Reach Totals Table

This table collects all of the irrigation returns that have been sent to each Reach and provides their sum. It is accessed via the "View 'Reach Totals' Summary Table" button located at the top of the worksheet.

These tables store the patterns specified in the Return Flow worksheet apart from the node by node calculations. They are stored in a separate worksheet than the Return Flows.

Engineering Notes:

The unused, or inefficient, portion of diversions are returned to the river either by direct surface runoff, or through the alluvial aquifer. For modeling purposes, an estimate must be made of both:

1. the location or locations on the river where the unused portion of diversions will return, and

2. the timing of those returns.

The irrigated acreage GIS theme was used to estimate these locations, shown in Table 7 for the upper division and Table 8 for the central division. In addition to the return flow node location in the river, Tables 7 and 8 show the return flow pattern used to represent each ditch system. Additional discussion of the return flow analysis is contained in Tasks 2A, 2B, and 2C Memorandum, Bear River Planning Study.

Table 7. Upper Division Return Flow Locations and Patterns

Model Node ID	Diversion Name	Return Nodes	Return Pattern
1.14	Hilliard East Fork	100% Ag-Sulphur Creek bl Reservoir	1
1.01	Lannon and Lone Mountain	30% Lewis Ditch 70% Confluence with Mill Ck	2
1.02	Hilliard West Side	100% Sulphur Creek Reservoir	1
1.03	Bear Canal	60% Sulphur Creek Reservoir 40% Ag-Sulphur Creek bl Reservoir	1
1.04	Crown and Pine Grove	25% Lewis 25% Cnfluence with Mill Ck 50% Myers No 2	2
1.05	McGraw (and Big Ben)	100% Lewis	2
1.06	Lewis	100% Myers No 1	2
1.07	Myers No 2	100% Myers No 1	2
1.08	Myers No 1	50% Booth 50% Ag-Sulphur Creek bl Reservoir	2
1.09	Myers Irrigation	100% Anel	2
1.11	Booth	100% Evanston Water Ditch	2
1.12	Anel	100% between Mill Creek and Sulphur Creek	2
1.13	Evanston Water Supply	50% Rocky Mountain Blythe 50% John Simms	2
1.15	Ag-Bear River Between Mill Creek and Su	100% Confulence Bear and Sulphur Creek	2
2.04	Ag-Sulphur Creek Above Resevoir	100% Sulphur Creek Res.	2
2.03	Ag-Sulphur Below Reservoir	100% Confulence Bear and Sulphur Creek	2
3.01	Evanston Water Ditch	100% Rocky Mountain Blythe	2
3.02	Rocky Mountain Blythe	70% John Simms 30% SP Ramsey	2
4.01	John Simms	50% SP Ramsey 50% Ag-Bear River between Sulphur and Yellow Creeks	2
4.02	SP Ramsey (also called Adin Brown)	50% Ag-Bear River between Sulphur and Yellow Creeks 50% Chapman	2
4.03	Ag-Bear River between Sulphur and Yello	100% Chapman	2
5.01	Chapman	100% Woodruff Narrows (WY)	2
5.02	Morris Brothers	30% Ag-Bear River between Yellow Creek and Woodruff 70% Woodruff Narrows	2
5.04	Ag-Bear River Yellow Creek and	100% Tunnel	2
5.03	Tunnel	100% Woodruff Narrows	2
7.01	Francis Lee	100% Ag-Utah Diversions	1
7.02	Bear River Canal	100% Ag-Utah Diversions	1

Table 8. Central Division Return Flow Locations and Patterns

Model Node ID	Diversion Name	Return Node	Return Pattern
7.03	Ag-Utah diversion	25% Node 7.04 70%USGS 26500 5% Pixley	2
8.01	Pixley Dam	100% Confluence with Smiths Fork	2
8.02	Ah-Bear river betweenTwin Fork and Smiths Fork	100% Confluence with Smiths Fork	2
10.01	Quinn Bourne	100% Button Flax	2
10.02	Button Flax	100% Emelle	2
10.03	Emelle	50% Cooper Ditch 50% Covey	2
10.04	Cooper	100% Covey	2
10.05	Covey	10% Whites Water 90% Confluence Bear and Smiths Fork	1
10.06	VH Canal	100% Whites Water	1
10.07	Goodell	100% Whites Water	1
10.08	Whites Water	100% Ag-Bear River below Smiths Fork	2
10.09	S. Branch Irrigation	100% Ag-Bear River below Smiths Fork	2
10.10	Ag-Smiths Fork	100% Ag-Bear River below Smiths Fork	2
11.01	Alonzo F. Sights	50% Oscar E. Snyder 50% Cook Brothers	2
11.02	Oscar E. Snyder	50% Cook Brothers 50% Bear River at Border Gage (1003950)	2
11.03	Cook Brothers	50% Bear River at Border Gage 50% Ag-Idaho Diversions	2

User Notes:

The Options Tables incorporate the information used in the computation of irrigation return flow quantities and their timing. The data in the first table, "Irrigation Return Patterns", consist of the percentages of water diverted which eventually will return to the river and be made available to downstream users. The values entered under "Pattern Type" are the amounts of water consumed or lost from the system.

The second worksheet table, "Irrigation Return Lags", controls the timing of these returns. Flows diverted in any month can be lagged up to three months beyond the month in which they are diverted. For example, Return Pattern No. 1 is as follows:

Month	0	1	2	3
Percent	50	15	25	10

For a diversion occurring in June, 50 percent of the Total Irrigation Returns (i.e., that portion not lost to consumptive use, evaporation, etc.) will return in June, 15 percent will return in July, 25 percent will return in August, and the remaining 10 percent will return in September.

Evaporation losses occur from any free water surface in the Bear River Basin, however, in this model development the only calculated evaporation occurs at the two main reservoirs in the system; Sulphur Creek and Woodruff Narrows Reservoirs. Evaporative losses from the river surface are accounted for in the reach gain/loss calculations. Similarly, evaporation losses from Stewart Dam are accounted for in the reach gain/loss calculation for that reach.

In the Bear River Model, two reservoirs were modeled: Sulphur Creek Reservoir located on Sulphur Creek (Node 2.02), and Woodruff Narrows Reservoir located on the mainstem of the Bear River (Node 6.01). Pixley Dam (Node 8.01) and Stewart Dam (Node 12.04) are included in the model as node points only; no storage is allowed at the sites, nor evaporation losses calculated. Evaporation losses are included in the mass balance calculations at each reservoir node.

Engineering Notes:

Pan evaporation data for the Green River, Wyoming, weather station were obtained through the High Plains Climate Center located in Lincoln, NE. No pan evaporation data were available within the Bear River Basin. Because of its proximity to the Bear River Basin, the Green River weather station was assumed to be representative of the basin. The pan evaporation data were adjusted by a factor of 0.6 to estimate evaporation from reservoirs and lakes. Precipitation data for the Evanston, Wyoming weather station were obtained through the Water Resources Data System (WRDS). Using average monthly pan evaporation data and mean monthly precipitation data, the net monthly reservoir evaporation estimates were computed and input to the model. The average annual net evaporation rate was 33.25 inches per acre (Table 9).

Table 9. Summary of Net Evaporation Calculations

Mean Monthly Data (Green River, WY)	Jan	Feb	Mar	Aprl	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Total
Average Monthly Gross Pan Evaporation (inches)	2.53	2.44	2.67	3.24	4.27	5.73	6.29	5.61	4.09	2.83	2.26	2.63	44.6
Average Monthly Precipitation (inches)	1.11	1.03	0.94	0.92	1.16	1.20	1.05	0.89	0.75	0.79	0.69	0.83	11.3
Average Net Evaporation (inches)	1.42	1.41	1.73	2.32	3.12	4.53	5.24	4.72	3.34	2.04	1.57	1.80	33.2

User Notes:

Monthly gross evaporation (inches) and total precipitation (inches) data are included in the table. Pan evaporation data must be adjusted to represent lake surface evaporation prior to entry. The worksheet then computes the net evaporation in inches and applies this factor to the average annual lake surface area.

Each non-storage node is represented in the spreadsheet by an inflow section, which includes inflow from the upstream node, irrigation returns, ungaged gains, and imports, if applicable; and an outflow section, which includes ungaged losses and diversions, if applicable. The algebraic sum of these flows are then the net outflow from the node. In the case of storage nodes, evaporation is included as a loss and flow can either go to or come from storage. Again, the water balance is done for the node and outflow is calculated. Figure 7 displays the Node 1.01 Table (Lannon and Lone Mountain) as an example.

Figure 7. Example Node Table

Engineering Notes:

This is the heart of the spreadsheet model where water budget calculations are performed for each node represented in the basin. Water balance is maintained in a river reach, or at least between reach gain/loss points, by performing the water budget calculations at each node until the outflow from the bottom node in each reach equals the gage flow at that point.

User Notes:

The Node Tables compute the flow available to downstream users (NET flow) using a water budget approach.

NET Flow = Total Node Inflow - Total Node Outflow

where:

Total Node Inflow	=	Flow from the node located upstream + Irrigation Returns to this the node + Ungaged reach gains (if available) +/- Basin Imports/Exports
and
Total Node Outflow	=	Diversions from the node + Ungaged Losses

The nodes must be organized in a consecutive order within each reach. Historic diversions at each node are automatically referenced from the Diversion Data worksheet. In the event that the historic demand cannot be met based upon available streamflow, the model will determine the amount that is available and enter that amount. In that event, a warning will be presented to inform the User that a diversion has been shorted.

The Bear River Basin, although of limited geographic size and well-documented by data sources, could not be completely modeled explicitly. Not all water features, such as small tributaries and diversions, are included in the computer representation of the physical system. Therefore, many features are aggregated and modeled, while many others are lumped together between measured flow points in the river by a modeling construct called ungaged reach gains and losses. These ungaged gains and losses account for all water in the budget that is not explicitly named and become a measure of how well the system incorporates physical features.

Engineering Notes:

Ungaged gains to the model include sources such as inflow from un-modeled tributaries, return flows from un-modeled diversions and groundwater inflow. Ungaged losses include factors such as un-modeled diversions, seepage and evaporation from the river. These factors are computed on a reach-by-reach basis using a water budget approach:

Ungaged Gains/Losses

=

Difference between downstream and upstream gages + Total diversions within the Reach - Total irrigation return flows to the Reach +/- Reservoir change in storage

The volume of ungaged gains and losses is a good measure of the adequacy of the model and the accuracy of the modeled features. If the volumes are high in comparison to the flow in the river or to diversions, then some major water features have not been modeled or have not been modeled correctly.

User Notes:

The worksheet collects all positive values (Reach Gains) and all negative values (Reach Losses) and creates the two Reach Summary Tables which are viewable with selection of the "Summary" button. Table 10 displays the Ungaged Gains and Losses determined for the Normal Year condition.

Table 10. Summary of Ungaged Reach Gains and Losses for the Normal Hydrologic Conditions

Ungaged Reach Gains

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Reach 1, 2 & 3	1081	1431	6466	12228	15308	7661	2606	0	0	0	357	936
Reach 4 & 5	507	528	1413	1288	6328	8156	4465	554	512	327	291	410
Reach 6	0	0	0	0	0	0	0	0	0	0	0	0
Reach 7	3366	3922	9805	8182	24962	41735	22679	3924	5049	3029	4046	3475
Reach 8	0	0	0	0	0	0	0	0	0	0	0	0
Reach 9 & 10	5233	5786	12819	24717	19196	26146	16230	7019	3837	4611	5551	5445
Reach 11	672	515	451	3194	1186	658	0	0	0	0	33	252
Reach 12	0	0	0	0	3665	0	0	0	1122	0	0	0

Ungaged Reach Loss

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Reach 1, 2 & 3	0	0	0	0	0	0	0	2289	1474	1417	0	0
Reach 4 & 5	0	0	0	0	0	0	0	0	0	0	0	0
Reach 6	0	0	0	0	0	0	0	0	0	0	0	0
Reach 7	0	0	0	0	0	0	0	0	0	0	0	0
Reach 8	2067	2630	5444	9603	14650	25580	14220	7373	3492	2483	2273	1641
Reach 9 & 10	0	0	0	0	0	0	0	0	0	0	0	0
Reach 11	0	0	0	0	0	0	1661	3595	2107	1080	0	0
Reach 12	2859	2553	740	2378	0	4912	3207	492	0	1940	1341	1705

In most cases, the Ungaged Reach Gains and Losses were computed for single reaches which are bound on both the upstream and downstream ends by gages. In those cases where the downstream end of a reach is not a gage, exceptions to this rule occur. These instances are discussed as follows:

A. Reaches 1, 2 and 3 Ungaged Gains and Losses were computed for the combined reaches and distributed between the upstream end of Reach 1 (Bear River) and Reach 2 (Sulphur Creek) in proportion to the ratio of the total annual discharges at the two upstream gages. For this computation, the water budget presented above consisted of the following terms:

Difference in Gaged Flows	=	Bear River at Evanston, WY (Gage 10016900) - Bear River near UT-WY State Line (Gage 10011500) - Sulphur Creek above Reservoir below La Chapelle Creek near Evanston, WY (Gage 10015700)
Total Diversions	=	Total Diversions Reach 1 + Total Diversions Reach 2 + Total Diversions Reach 3 + Change in Reservoir Storage (Sulphur Creek)
Total Return Flows	=	Total Returns Reach 1 + Total Returns Reach 2 + Total Returns Reach 3

B. Reaches 4 and 5

Ungaged Gains and Losses were computed for the combined reaches. Combined Gains were added to the upstream end of Reach 4 and combined Losses were taken at the downstream end of Reach 5. For this computation, the water budget presented above consisted of the following terms:

Difference in Gaged Flows	=	Bear River above Reservoir, near Woodruff, UT (Gage 10020100) - Bear River at Evanston, WY (Gage 10016900)
Total Diversions	=	Total Diversions Reach 4 + Total Diversions Reach 5
Total Return Flows	=	Total Returns Reach 4 + Total Returns Reach 5

C. Reaches 9, 10 and 11 Ungaged Gains and Losses were computed for the combined reaches and distributed between the upstream end of Reach 9 (Bear River) and Reach 10 (Smiths Fork) in proportion to the ratio of the total annual discharges at the two upstream gages. For this computation, the water budget presented above consisted of the following terms:

Difference in Gaged Flows	=	Bear River below Smiths Fork, near Cokeville, WY (USGS 10038000) - Smiths Fork near Border, WY (USGS 1003200) - Bear River below Pixley Dam, near Cokeville, WY (USGS 10028500)
Total Diversions	=	Total Diversions Reach 9 + Total Diversions Reach 10 + Total Diversions Reach 11
Total Return Flows	=	Total Returns Reach 9 + Total Returns Reach 10 + Total Returns Reach 11

The following sections present information pertinent to each specific reach in the Bear River Model. Included in these sections are listings, issues and assumptions pertaining to each reach.

2.4.1 Reach 1

Reach 1 consists of the following nodes listed in the order they are placed in the model:

This Reach is the upstream end of the Bear River Model. Inflow to Reach 1 at Node 1.00 (USGS Gaging Station 10011500) serves as the beginning of the water budget computations. The reach ends at the confluence with Sulphur Creek. Mill Creek is not modeled explicitly, however, a node has been added at the confluence with the Bear River (Node 1.18) to accommodate irrigation return flows which it conveys. Aggregate Diversion BR-1 (Node 1.15) represents the aggregated diversions which are not modeled individually. The diversion for Hilliard East Side is not explicitly modeled because it is above the most upstream gage, USGS 10011500. The diversion, though, is included in the summary tables and in the Compact Allocations calculations in the Results Worksheets.

2.4.2 Reach 2

Reach 2 consists of the following nodes:

Reach 2 consists of nodes on Sulphur Creek including Sulphur Creek Reservoir. Inflow to the reach is defined as the flow at USGS Gaging Station 10015700 and the reach ends at the confluence with the Bear River. The target for Sulphur Creek Reservoir outflow has been set equal to the gage data measured at USGS Gaging Station 10015900. Changes in reservoir storage are computed as the difference between reservoir inflow (NET Flow at Node 2.01) and outflow (USGS Gaging Station 10015900) minus evaporative losses.

AggDiv SC-1/Broadbent (Node 2.01) and AggDiv SC-2 (Node 2.03) represent aggregated diversions which are not modeled individually. Basin imports to Sulphur Creek via the Broadbent Ditch are added at Node 2.01. Ungaged Reach Gains for Reach 2 were added to the model downstream of Sulphur Creek Reservoir at Node 2.03.

2.4.3 Reach 3

Reach 3 consists of the following nodes:

Reach 3 begins at the confluence of the Bear River and Sulphur Creek (Node 3.00) and ends at USGS Gaging Station 10016900. Ungaged losses in the reaches 1 through 3 are subtracted from the flow in this reach at Node 3.02.

2.4.4 Reach 4

Reach 4 consists of the following nodes:

Reach 4 begins at the USGS Gaging Station 10016900 (Node 4.00) and ends at the confluence of the Bear River and Yellow Creek (Node 5.00). Aggregate Diversion BR-2 (Node 4.03) represents the aggregated diversions in the Upper Wyoming section of the Upper Division which are not modeled individually.

2.4.5 Reach 5

Reach 5 consists of the following nodes:

Reach 5 begins at the Confluence of the Bear River and Yellow Creek (Node 5.00) and ends at USGS Gaging Station 10020100. Yellow Creek is not modeled explicitly, however, a significant amount of irrigation returns are conveyed by it. Therefore, a node has been added at the confluence with the Bear River to accommodate these flows (Node 5.00). Aggregate Diversion BR-3 (Node 5.03) represents other aggregated diversions in the Upper Wyoming section of the Upper Division which are not modeled individually.

2.4.6 Reach 6

Reach 6 consists of the following nodes:

Reach 6 consists of the USGS Gaging Station 10020100 and Woodruff Narrows Reservoir. Reservoir outflow equals gaging data measured at USGS Gaging Station 10020300. Changes in reservoir storage are computed as the difference between reservoir inflow (NET Flow at Node 6.00) and outflow (USGS Gaging Station 10020300) minus evaporative losses.

2.4.7 Reach 7

Reach 7 consists of the following nodes:

This reach begins with the Woodruff Narrows Outflow (Node 7.00) and ends at the USGS Gaging Station 10026500. It incorporates all of the Lower Utah diversions in the Upper Division at Node 7.03. None of the Lower Utah diversions were modeled individually.

2.4.8 Reach 8

Reach 8 consists of the following nodes:

Reach 8 begins at the USGS Gaging Station 10026500 and ends at Pixley Dam and includes all diversions from the two diversion dams. This is the last reach in the Upper Division.

2.4.9 Reach 9

Reach 9 consists of the following nodes:

This reach is the uppermost reach of the Central Division as defined in the Bear River Compact. It begins at the Pixley Dam outflow (Node 9.00) and ends at a node representing the confluence of the Bear River with Smiths Fork. Aggregate Diversion BR-4 (Node 9.02) represents the aggregated diversions which are not modeled individually.

2.4.10 Reach 10

Reach 10 consists of the following nodes:

This reach models the Smiths Fork which is tributary to the Bear River. Inflow to the reach is measured at the USGS Gaging Station 10032000 (Node 10.01) and ends at the confluence with the Bear River (Node 9.01). The diversion for Quinn Bourne is not explicitly modeled because it is above the most upstream gage, USGS 10032000. The diversion, though, is included in the summary tables and in the Compact Allocations calculations in the Results Worksheets. Aggregate Diversion SF-1 (Node 10.10) represents the aggregated diversions from the Smiths Fork which are not modeled individually.

2.4.11 Reach 11

Reach 11 consists of the following nodes:

This reach begins at the USGS Gage 10038000 downstream of Smiths Fork (Node 11.00) and ends at the USGS Gage 10039500 at the Wyoming / Idaho state line. Aggregate Diversion BR-5 (Node 11.01) represents the aggregated diversions of Wyoming in the Central Division which are not modeled individually.

2.4.12 Reach 12

Reach 12 consists of the following nodes:

Reach 12 begins at the USGS gage 10039500 and ends downstream of Stewart Dam in Idaho. It includes flows diverted by the Rainbow Inlet (Node 12.03). Aggregate Diversion BR-5 (Node 12.02) represents 12 aggregated Idaho diversions which are not modeled individually.

2.5 The Results Worksheets

Several forms of model output can be accessed from the Summary Options worksheet. These include river flow data (nodes or reaches), target and actual diversions (nodes, reaches, or comparison to historic), and evaluations of Compact Allocations (Upper or Central Divisions).

2.5.1 Outflows

This worksheet summarizes the flows at all nodes in the model. The "Outflow Calculations: By Node" table summarizes the net flow for all nodes. Note that this table is included with each model printout (Appendices A, B, and C). The nodes are grouped by reach. The "Outflow Calculations: By Reach" table presents the net flow for each reach. Table 11 presents the Reach Summary Table from the Normal Year condition as an example. A comparison of flows at significant node points which are USGS Gaging locations is also included.

Table 11. Summary of Reach Outflow Durning Normal Hydrologic Conditions

Note 1: USGS Average = average annual streamflow (ac-ft) for entire study period (1971-1998)
Note 2: NA = Reach does not terminate at a gaging station

2.5.2 Diversions

This worksheet summarizes the diversions at all nodes in the model. The "Summary of Diversion Calculations: By Node" tables summarizes the computed diversions which are made at each node. The nodes are grouped by reach. Note that this table is not incorporated into this memo, but is included within the model printouts (Appendices A, B, and C). The "Summary of Diversion Calculations: By Reach" table presents the total diversions taken within each reach. Table 12 presents the corresponding table from the Normal Year Model as an example. The "Comparison of Estimated vs Historic Diversions" table presents comparison results and would indicate if any shortages occurred to target diversion volumes (Table 13).

Table 12. Total Diversion per each Reach During Normal Hydrologic Conditions

Table 13. Comparison of Estimated v. Historic Diversions during Normal Hydrologic Conditions

2.5.3 Compact Allocations

An effort was made to incorporate sufficient detail in the spreadsheet models to determine whether water emergency conditions exist as defined in the Bear River Compact for either the Upper or Central Divisions. The Water Commissioners worksheets for both divisions were computerized and all appropriate flows and diversions were tabulated. These tables determine whether an emergency condition exists; however, no attempt was made in the model to restrict diversions based on this determination.

User Notes:

The "Bear River Commission Water Allocation: Upper Division" table (Table 14) uses the Water Commissioner's worksheet to determine if a water emergency exists in the Upper Division under the current scenario. If so, the worksheet computes the allocations for the Upper Utah, Upper Wyoming, Lower Utah, and Lower Wyoming sections, as defined in the Bear River Compact.

Table 14. Bear River Commission Water Allocation Worksheet: Upper Division (Normal Hydrologic Conditions)

The "Bear River Commission Water Allocation: Central Division" table (Table 15) uses the Water Commissioner's worksheet to determine if a water emergency exists in the Central Division under the current scenario. If so, the worksheet computes the allocations for the State of Wyoming and Idaho are computed as defined in the Bear River Compact.

Table 15. Bear River Commission Water Allocation Worksheet: Central Division (Normal Hydrologic Conditions)

A spreadsheet model of the Bear River Basin was developed which simulates the operation and flows in the Bear River system. All significant diversions were modeled in addition to two tributaries, Sulphur Creek and Smiths Fork. Prior to use, a full analysis and calibration of the model is required to insure that the results of model scenarios properly reflect the hydrology and operational aspects of the basin. The calibration effort is contained in the Task 3C Memorandum, Surface Water Model Calibration.

The value of this model to users in the basin is in assessing the impact of proposed projects to the flows in the river. By simulating the river operations with and without the project, the change in flows can be analyzed for project benefits and system costs. This will be discussed in detail in the Task 3D Memorandum, Available Surface Water Determination.

To the Bear River Basin Water Plan