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51.1248 (Greybull Valley) J

GEl Consllitants, Inc.

GREYBULL VALLEY DAM AND RESERVOIR PROJECT Level II - Phase VI

Alternatives Evaluation Report

Prepared by:

Wyoming Water Development Commission GEl Consultants, Inc. Cheyenne, \Vyonling CD - 0 and the In association with: _It) -~ ~ Greybull Valley Irrigation District States West Water Resources Corporation ~ Emblem, Wyoming ====mN ------====0 m ('I') 5660 Greenwood Plaza Blvd., Suite 202 August 1994 ~ Englewood, CO 80111 Project 94071 (303) 779-5565 GREYBULL VALLEY DAM AND RESERVOIR PROJECT Level II - Phase VI Alternatives Evaluation Report

Prepared for:

Wyoming Water Development Commission Cheyenne, Wyoming

and

Greybull Valley Irrigation District Emblem, Wyoming

Prepared by

GEl Consultants, Inc. 5660 Greenwood Plaza Blvd., Suite 202 Englewood, Colorado 80011

August 1994 Project 94071

, P.E. Members of the Greybull Valley Irrigation District (GVID) currently face frequent irrigation shortages that can result in substantial crop losses, especially to water-dependent crops such as sugar beets and dry beans. The average annual expected cost of these crop failures has been estimated to be approximately $1.5 million. The present value of this average annual cost, assuming a four percent discount rate over a 50-year period, is over $34 million. Several previous studies have indicated that the key to reducing the potential for periodic crop failures in the Greybull River Valley is to provide supplemental storage for water which is currently available in the watershed [HDR, 1988], [Bereman, 1989].

Consistent with previous evaluations, recent engineering studies have focused on the Lower Roach Gulch Dam and Reservoir project [GEl, 1994-2]. The sponsor's (GVID) preferred project configuration includes a 150-foot-high zoned-earth embankment dam located near the mouth of Roach Gulch. Water would be delivered to the 30,000 acre-foot reservoir via a six-mile-long water supply canal, which would divert excess river flows from the Greybull River. The estimated average annual water yield from the project would be approximately 26,500 acre-feet.

A large portion of the project will be located on lands administered by the U.S. Bureau of Land Management (BLM). Hence, the approval of a BLM Right-of-Way application and the approval of a U.S. Army Corps of Engineers (COE) 404 permit for the project will be a major federal action. Compliance with the National Environmental Policy Act (NEPA) will require that an Environmental Impact Statement (EIS) be prepared for the project.

The sponsor's purpose and need for the project can be summarized as follows:

The purpose of the Greybull Valley Dam and Reservoir Project is to provide supplemental lower basin storage of water that can significantly reduce crop failures and increase crop yields. Lower river basin storage will also provide river re-regulation benefits that will reduce current water waste by providing more timely delivery of water to the majority of the irrigated lands and provide the ability to capture return flows for beneficial use during the non-irrigation season. Approximately 30,000 acre-feet of supplemental irrigation water are needed to meet the sponsor's current demands for supplemental water.

During the EIS process an evaluation of reasonable and practicable alternatives must be performed in accordance with the alternatives analysis guidelines of Section 1502.14 of the Council on Environmental Quality Regulations for the Implementation of NEPA (40 CFR 1500-1508 as amended) and Section 404(b) of the Clean Water Act. Hence, a reconnaissance level initial screening of practicable alternatives to meet the GVID's purpose and need has been completed by GEl Consultants, Inc. (GEl) under contract to the Wyoming

94071\REPOR1\TEXT. VI i Water Development Commission (WWDC). This information can be used to provide more focused and efficient study efforts during the future EIS process.

Several reconnaissance level alternatives were developed to describe the full range of reasonable and practical projects that would meet the sponsor's purpose and need in a cost effective manner. These included the following types of alternatives:

• transbasin diversions • enlargement of existing Upper and Lower Sunshine Reservoirs • other off-channel reservoir sites • other main stem river storage sites • groundwater alternatives • conservation alternatives • No Action alternative

Consistent with the above project types and GVID purpose and need, fifteen alternatives were developed based on previous stu"dies and discussions with the WWDC staff and the GVm. A comparative evaluation qf the alternatives was then completed in which all alternatives were identified as either primary or secondary projects. Primary alternatives were defined as those projects that appear to provide a practicable and cost effective solution to the sponsor's purpose and need. Secondary alternatives are those projects which appear to have serious technical or economic obstacles or are otherwise not practical solutions to the OVID's water supply challenge.

A two-staged screening process was used to compare the relative merits of the alternatives. The first stage of screening, called coarse screening, evaluated the ability of each project to meet the sponsor's purpose and need. Previous studies have identified a need to provide at least 26,500 acre-feet of supplemental water supplies to the GVID on an average annual basis. Of equal importance to the GVID is the ability to improve the operational efficiency of their water supply system with storage located in the lower portion of the river valley, closer to the majority of the end users. Hence, during coarse screening, any project which could not provide a yield of 26,500 acre-feet with storage located in the lower portion of the basin was classified as a secondary alternative. Four of the initially considered 15 alternatives met the requirements of coarse screening.

The second stage of screening, termed fine screening, evaluated the cost of the remaining alternatives. The objective of fine screening was to categorize the remaining four projects to determine if they were too expensive for the GVID to finance as secondary alternatives. Previous economic evaluations indicate that there is a high interest in purchasing supplemental irrigation supplies at less than $21 per acre-foot [GEl, 1994-2]. However, the demand for additional water drops dramatically above this apparent threshold level. Only three alternatives remained as primary alternatives as a result of fine screening. These alternatives are recommended for consideration by the GVID, WWDC, and lead Federal agencies as primary alternatives during the future EIS scoping process. The primary alternatives which met the conditions of both stages of screening are as follows:

94071\REPOR1\TEXT. VI ii • Lower Roach Gulch Reservoir • Blackstone Gulch Reservoir • No Action

It should be noted that the No Action alternative did not meet the purpose and need criteria associated with coarse screening and should not be considered as a viable alternative. However, because it must be evaluated in the EIS in accordance with NEPA, it has remained as a primary alternative.

The initial screening process was performed by GEl based on our experience with other similar water resources projects, but lacks one of the key elements of success that will be required during the EIS. The key requirement is that the screening and permitting decision analysis must be conducted in an open and public format where all project stakeholders have the opportunity to provide input. Public involvement was not included in this evaluation because of the reconnaissance nature of the work and because public involvement will occur during future EIS hearings. During the EIS additional primary alternatives may be identified or additional studies may also result in the reclassification of some secondary alternatives as primary alternatives.

A preliminary, systematic and defensible decision support system (DSS) model has also been developed as part of this work. The development of a DSS, including the planning hierarchy if developed as early as possible during the EIS process, has the potential to prevent unnecessary and inefficient data gathering efforts and provide the sponsor with the ability to establish responsible management of the process.

94071\REPORTITEXT.VI iii EXECUTIVE SUMMARY ...... i

1.0 INTRODUCTION ...... 1-1 1.1 WYOMING WATER DEVELOPMENT (WWDC) PLANNING PROCESS. 1-1 1.2 REPORT OBJECTIVE ...... 1-1 1.3 OVERVIEW OF PROJECT DEVELOPMENT ...... 1-2 1.4 SCOPE OF WORK ...... 1-3 1.5 AUTHORIZATION ...... 1-3 1.6 PROJECT TEAM ...... 1-4

2.0 BACKGROUND INFORMATION ...... 2-1 2.1 PROJECT HISTORY ...... 2-1 2.2 PURPOSE & NEED ...... 2-4

3.0 FORMULATION OF ALTERNATIVES ...... 3-1 3.1 PREVIOUS STUDIES ...... 3-1 3.2 CRITERIA FOR THE FORMULATION OF ALTERNATIVES ...... 3-3 3.3 INITIAL ALTERNATIVES THAT WERE NOT CONSIDERED ...... 3-5 3.4 DESCRIPTIONS OF ALTERNATIVES CONSIDERED FOR SCREENING 3-6 3.4.1 Enlargement of Upper Sunshine Reservoir ...... 3-6 3.4.2 Rawhide Creek Dam ...... 3-7 3.4.3 Spring Creek Dam ...... 3-7 3.4.4 Blackstone Gulch Dam ...... 3-7 3.4.5 Lower Roach Gulch Dam ...... 3-8 3.4.6 Mainstem Dam Site A ...... 3-8 3.4.7 Mainstem Dam Site B ...... 3-8 3.4.8 Mainstem Dam Site C ...... 3-9 3.4.9 Mainstem Dam Site D ...... 3-9 3.4.10 Mainstem Dam Site E ...... 3-9 3.4.11 Mainstem Dam Site F ...... 3-9 3.4.12 Transbasin Diversion from the Shoshone River ...... 3-10 3.4.13 Conservation ...... 3-10 3.4.14 Groundwater ...... 3-11 3.4.15 No Action ...... 3-11

4.0 COMPARATIVE ANALYSIS ...... 4-1

94071\REPOR1\TEXT.VI iv 5.0 EIS MANAGEMENT FRAMEWORK •.••.•...••.•.•.•.•..•.••... 5-1 5.1 PROPOSED METHODOLOGY FOR COMPARING AND RANKING EIS ALTERNATIVES ...... 5-1 5.2 EXAMPLE APPLICATION OF SIMPLIFIED SCREENING MODEL .... 5-3 5.3 OTHER ISSUES AND PLANNING CONSIDERATIONS ...... 5-3 5.3.1 Primary Alternatives ...... 5-3 5.3.2 Secondary Alternatives ...... 5-4

6.0 CONCLUSIONS ..•...•...•.•...... •.....•••.•••.••••.•• 6-1 6.1 PRIMARY ALTERNATIVES FOR EIS CONSIDERATION ...... 6-1 6.2 RECOMMENDATIONS FOR FUTURE EIS MANAGEMENT ...... 6-1

7.0 REFERENCES ••.••..•.••.•.•.•.••.•.....•••••.••.••••.•.•• 7-1

APPENDIX A: Groundwater Evaluations APPENDIX B: Economic Costs of the No Action Alternative APPENDIX C: Development of Estimated Total Project Investment APPENDIX D: Development of Estimated Project Yields

94071\REPORWfEXT.VI v Table No.

3.1 Summary of Previously Proposed Alternatives ...... 3-3

4.1 Summary of Initial Screening Criteria ...... 4-2

C.1 General Cost Estimate Formula ...... C-2 C.2 Summary of Enlargement and Off-channel Investment ...... C-3 C.3 Summary of Mainstem Dam Investment ...... C-4 C.4 Summary of Non-storage Dam Investment ...... C-5

D.1 Summary of Lower Reservoir Demands and Systemwide Yields ...... D-3 D.2 Summary of the Development of Alterative Total Project Investment . .. D-4

9407I\REPOR1\TEXT.VI vi After Figure No. Page

2.1 Greybull River Location and Vicinity Map ...... 2-1 2.2 Greybull River Profile ...... 2-1 2.3 Comparison of Meeteetse Flows vs. Lower River Irrigation Demands ... 2-2

3.1 Plan of Initially Evaluated Alternatives ...... 3-1 3.2 General Off-Channel and Main Stem Dam Cross Sections ...... 3-4 3.3 Enlargement of Upper Sunshine Reservoir ...... 3-6 3.4 Cross Section of Enlarged Upper Sunshine Dam ...... 3-6 3.5 Upper and Lower Sunshine Reservoir Area-Capacity Curves ...... 3-6 3.6.1 Off-channel Reservoir - Rawhide Creek ...... 3-7 3.6.2 Off-channel Reservoir - Rawhide Creek ...... 3-7 3.7 Off-channel Reservoir - Spring Creek ...... 3-7 3.8 Off-channel Reservoir - Blackstone Gulch ...... 3-7 3.9 Off-channel Reservoir - Lower Roach Gulch ...... 3-8 3.10 Mainstem Reservoir Site A ...... 3-8 3.11 Mainstem Reservoir Site B ...... 3-8 3.12 Mainstem Reservoir Site C ...... 3-9 3.13 Mainstem Reservoir Site D ...... 3-9 3.14 Mainstem Reservoir Site E ...... 3-9 3.15 Mainstem Reservoir Site F ...... 3-9 3.16 Shoshone River Transbasin Diversion ...... 3-10 3.17 Farmers and Bench Canal Systems ...... 3-10

4.1 Initial Screening Process Schematic ...... 4-1

5.1 Preliminary Planning Functional Hierarchy for the Greybull Valley Project 5-2 5.2 Example Initial Screening Model Functional Hierarchy ...... 5-3 5.3 Example Initial Screening Model Preference Relationships ...... 5-3 5.4 Example Results of Initial Screening Model ...... 5-3

94071\REPOR1\TEXT. VI vii 1.1 WYOMING WATER DEVELOPMENT (WWDC) PlANNING PROCESS

The WWDC was created in 1975 to plan, finance, construct and operate facilities for the conservation, storage, delivery and use of water in the State of Wyoming. Water projects are developed under the WWDC program in a three-step progress described as follows:

• Level I - Preliminary Analysis • Level II - Feasibility Study • Level III - Development Plans and Construction

Level I studies provide preliminary planning level information relative to the project. A project can proceed to Level II evaluations if an opportunity exists to develop water for beneficial use and it is apparent that economic, technical, legal, and environmental challenges can be fully addressed leading to permit acquisition. A project progresses to the Level III development stage if the project sponsor and the WWDC commit to project completion. Project permitting, final design and construction generally occur during the Level III stage of project development. Each project must be approved by the Wyoming State Legislature prior to proceeding to the next level of study.

1.2 REPORT OBJECTIVE

The information submitted in this report is intended to provide a focus to and eliminate unnecessary study efforts during the EIS. Hence, the objective of this report is to provide reconnaissance level information for the project sponsors and lead Federal agencies for their use in formulating reasonable and practicable water supply alternatives consistent with meeting the sponsor's purpose and need. The alternatives discussed herein will be considered during the scoping phase of the Environmental Impact Statement (EIS). Additional information relative to the project purpose and need is included in Section 2.

This report contains an introductory section, a section which summarizes project background information and sections which describe the formulation and comparison of project alternatives. Our conclusions include recommendations for an EIS management framework and recommendations for primary alternatives that appear appropriate for inclusion in the EIS.

94071\REPOR1\TEXT.VI 1-1 1.3 OVERVIEW OF PROJECT DEVELOPMENT

Since 1990, the project sponsor, the Greybull Valley Irrigation District (GVID) has been working with the WWDC to develop conceptual designs to provide supplemental irrigation water to its members. GEl Consultants, Inc. (GEl) has been the prime engineering consultant responsible for the development of this information. These and other previous studies are summarized in Section 3.1 of this report.

The sponsor's preferred project configuration consists of a 150-foot-high, zoned-earth dam located at the mouth of Roach Gulch in Park County, Wyoming. The dam would impound a 30,OOO-acre-foot, off-channel storage reservoir which would be supplied by a six-mile-long water supply canal. The canal would convey deliveries from the Greybull River to the reservoir. The project, referred to in the remainder of this report as the Lower Roach Gulch project, is described in the Level II, Phase V Final Conceptual Design Report [GEl, 1994-2].

Previous studies associated with this project have been funded by the WWDC and have focused on issues related to technical feasibility and preliminary assessment of environmental impacts. During Level 11 evaluations, preliminary meetings and discussions have been held with the U.S. Bureau of Land Management (BLM) and the U.S. Army Corps of Engineers (COE). These discussions have confirmed that the project will require approval of a BLM Right-of-Way application (standard form 299) for the us~ of BLM lands associated with the project. In addition, a COE 404 permit will be required to approve the dredging and filling of materials into the waters of the United States [GEl, 1994-2].

It is our present understanding that the WWDC and GVID will be finalizing a memorandum of understanding (MOU) in the near future with the COE and the BLM relative to the project EIS. We understand that both the BLM and COE have indicated that the project would be considered as a major federal action which would require the completion of an EIS in accordance with the National Environmental Policy Act (NEPA). It is also our understanding that the COE will be the lead agency responsible for preparation of the EIS.

Significant portions of the EIS will include: 1) conducting public scoping meetings to identify key issues for consideration in the EIS; 2) development of the project purpose and need; 3) evaluation of alternatives to meet the project purpose and need; 4) preparation of a description of the existing environment in the vicinity of the project; and 5) an assessment of environmental consequences and appropriate mitigation requirements associated with the project.

Permit applications have not yet been prepared for the project nor has a Memorandum of Agreement (MOA) been finalized among the GVID, the WWDC, and other Federal and State agencies. Other project stakeholders identified to date will include the U.S. Fish and Wildlife Service (FWS), the U.S. Environmental Protection Agency (EPA) and the Wyoming Game and Fish Department (WG&FD). Additional public project stakeholders will have the opportunity to become involved in the project permitting decision through the EIS process.

94071\REPORT\TEXT. VI 1-2 1.4 SCOPE OF WORK

Alternatives analysis required during the EIS must be completed in accordance with the guidelines prescribed by Section 404(b) of the Clean Water Act as well as Section 1502.14 of the Council on Environmental Quality Regulations for the Implementation of NEPA (40 CFR 1500-1508 as amended). In accordance with the spirit of these guidelines, the Level II, Phase VI scope of work included: 1) a review of available project alternative information provided by the WWDC and the GVID; 2) reconnaissance level engineering evaluations of alternatives to the current project configuration; 3) a comparative evaluation of the alternatives; and 4) preparation of draft and final reports which summarize the work.

The scope of work for the Level II, Phase VI study includes evaluation of the following alternatives:

• transbasin diversions • enlargement of existing Upper and Lower Sunshine Reservoirs • other off-channel reservoir sites • other main stem sites • groundwater alternatives • conservation alternatives • No Action alternative

1.5 AUTHORIZATION

This pre-EIS, Level II contract was authorized by the Wyoming State Legislature and administered by the Wyoming Water Development Commission (WWDC) under Contract For Services No. 9-01064, dated June 6, 1990, and Contract Amendment No.9, dated March 16, 1994.

94071\REPORT\TEXT.VI 1-3 1.6 PROJECT TEAM

This report was prepared by GEl Consultants, Inc. (GEl) in association with States West Water Resources Corporation (SWWRC). The following personnel contributed to the preparation of this report:

• Project Manager (GEl) Keith A. Ferguson, P .E. • Project Engineer (GEl) Steve Jamieson, P.E. • Technical Review (GEl) VIi Kappus, P.E. • Geotechnical Engineer (GEl) Karen Knight, P.E. • Civil Engineer (GEl) Brian Johnson, P.E. • Project Manager (SWWRC) Michael 0' Grady • Hydrologist (SWWRC) Karen Mumper • Groundwater Specialist (SWWRC) Marlin Lowry, P.G. • Groundwater Specialist (SWWRC) Dave McElhaney, P.G.

Mr. Jon Wade, P.G., was the WWDC project manager and Mr. Dave Edwards of the GVID provided valuable information during the performance of our evaluations and preparation of this report.

94071\REPORT\TEXT.VI 1-4 A brief history and background of the project, particularly as it relates to the project purpose and need, are provided in this section.

2.1 PROJECT HISTORY

The Greybull River Valley is located in southern Park and Big Horn Counties in northwest Wyoming as shown on Figure 2.1. The headwaters of the Greybull River and its major tributary, the Wood River, originate at nearly elevation 11,0001 in the Absaroka Mountain range. The Greybull River is approximately 90 miles long and drops to approximately elevation 3870 at its confluence with the Bighorn River near the Town of Greybull. A profile of the Greybull and Wood Rivers is provided on Figure 2.2. This figure also shows the location of some of the alternatives considered during this evaluation.

Most of the GVID shareholders are farmers who irrigate approximately 65,000 acres of land in the Greybull River Valley and on the Emblem Bench. The Emblem Bench is located in the Dry Creek drainage west of the Town of Greybull. Crops grown in the Greybull River Valley include sugar beets, dry beans, malt barley, alfalfa, and smaller acreages of corn, hay, and pasture land. Most of the farmers in the lower reaches of the valley receive water from either the Farmers or Bench Canal Companies which are separate companies from the GVID. The development of the extensive Farmers and Bench Canal systems began in approximately 1890 and the companies now have combined diversion rights to approximately 470 cubic feet per second (cfs). Both canal companies share joint ownership and maintenance of the diversion structure on the Greybull River, the first 6,000 feet of canal, and the wasteway structure. The Farmers and Bench Canal diversion from the Greybull River is located in the southeast quarter of Section 7, T.51N., R.97.W.

Precipitation in the Greybull Basin varies significantly with elevation along the river. In the high mountains in the western portion of the basin average precipitation varies from 40 to 50 inches per year, mainly in the form of snowfall [HDR, 1988]. However, the lower reaches of the river valley near the Town of Greybull receive only about six inches of precipitation per year, mainly in the form of rainfall which occurs between the months of May and September [HDR, 1988]. Therefore, supplemental irrigation water is essential throughout the growing season to prevent crop failure.

In 1919, 1955, and 1960 severe droughts in the area originally prompted the formation of the GVID for the purpose of constructing Upper and Lower Sunshine Reservoirs in 1939 and 1972, respectively. These reservoirs, shown on Figure 2.1, allow the irrigators to capture

lAB elevations will be reported in feet, National Geodetic Vertical Datum.

94071\REPORl\TEXT.VI 2-1 '.u...... , .. u ILL RESERVOIR

, GREYBULL RIVER PROJECT LOCATION MAP BAIlIN BOUNDARY (NOT TO SCALE)

UPPER SUNSHINE RESERVOIR LEGEND

GREYBULL RIVER BASil\) BOUNDARY

RIYER RIVERS, CREEKS AND CANALS BASIN BOUtIDARY •• J "4.. HIGHWAYS

TOWNS GREYBULL RIVER VICINITY MAP IRRIGA TED ACRES o 3 6 12 18 II- SCALE IN MILES EXISTING RESERVOIRS

WWDC /GVID GREYBULL VALLEY PROJECT GREYBULL RIVER CHEYENNE, WYO~ING LOCATION AND LEVEL II - PHASE VI VICINITY MAP

rj) GEl Consultants, Inc. - PROJECT NO. 94071 ~AY 1994 FIGURE 2.1 DISTANCE FROM HEADWATERS OF WOOD RIVER (MILES) LEGEND o 10 20 30 11.000 4----'-----...L..---=----'----,------' RAWDmE CREEK DAM - OFF -CHANNEL RESERVOIR

DAM SITE C - MAINSTEM RESERVOIR

- PROPOSED RESERVOIR 10.000 NOTE 1. EXISTING FEATURES ARE SHOWN BELOW THE HYDRAULIC GRADE LINE. OFF-CHANNEL AND MAINSTEM AL TERNA liVES CONSIDERED ARE SHOWN 9000 ABOVE THE HYDRAULIC GRADE LINE.

IRAWtlDE CREIEK DAM. N.W.S•• El. 8440 o ~ 8000 DAM SITE F, N. W.S., El.. 8230 z DAM SITE E, N. W.S., EL 6212 I SUNSHINE CANAL DAM SITE ~ N. W.S., EL 11130 'P DIVERSION. EL. 6690 I.&J DAM $lTE ~ No »:S., EL II()gS I.&J ~ 7000 z UPPER SUNSHINE DAM. SPRING CREEK DAM. N.W.S•• EL. 8074 o N.W.S .• EL. 6595 F ~ I.&J .J I.&J 6000 LOWER SUNSHINE DAM.r ...... ;::::lI~======.. ::E. ~~.. -=.~~. ~ ...~ I... _ ... _ ... _ ... 1 DAM SITE ~ N.w.s, EL - N. W.S.. EL. 6277 BLACKSTONE GULCH IDAM. NoW.S •• EL. 1181 WOOD RIVER CANAL DIVERSION. EL. 6635 LOWER ROACH GULCH DAM. N.W.S•• EL. 4148

_____ -----'---.,;;:;::=:::::!-,...... _ ... _ ... _ ... DAM SITE A, No w.s., EL 4g24 5000 CONFLUENCE OF GREYBULL AND -.£ WOOD RIVERS. EL. 6102 MEETEETSE CREEK CONFLUENCE. EL. -.!.!. 5610 SPRING CREEK RAWHIDE CREEK CONFLUENCE OF GREYBULL AND ~ ~ CONFLUENCE. EL. 5692 CONFLUENCE. EL. 6086 BIG HORN RIVERS. EL. 3870 4000 I&J DIVERSION FOR '"I i~ BENCH AND FARMERS \) ~~ S :2 CANALS. EL. 4642--oJ ;:;: ! 3500~---~----~---~----~----r·-----'----~~---+----r-----~ .... o 10 20 ~ 40 ~ ~ ro 80 90 100 ~ DISTANCE FROM HEADWATERS OF GREYBULL RIVER (MILES) ! i GREYBULL RIVER PROFILE CHErrvN~E! ~"J~ING GREYBUll VAllEY PROJECT GREYBULL RIVER PROFILE ~ LEVEL II - PHASE VI

~ L..______-____ -__ W_O_OD_R_IVE_R_P_RO_F_IL_E ______._- .....-II-i: ::_:::;::::...;G;;.;;E;.;I....;;.CO;;.;n;;,;s;.;;u:.:.lt;.:a:.:.n:.::ts:::..~In~C::.: •...I ..L.. -_-:_ -P_R:O:J:E-C_ ....T_ -_N:O:. :9: ..:0 ...7:1_-_-_-:'--_-- ..._-A_V::1:9:9- .._-_ -':_F-I_G:U:R:E:::2-._2: water from wetter years for use during drought periods. These reservoirs also provide the GVm with the opportunity to capture excess river flows in the winter and spring run-off periods for use later in the summer when irrigation demands are the highest. Typical months of excess river flows and irrigation shortages are shown on Figure 2.3.

Despite the construction of Upper and Lower Sunshine Reservoirs, many farmers who attempt to raise crops such as dry beans and sugar beets continue to suffer from periodic irrigation shortages. Hence, the primary purpose of the project is to provide supplemental irrigation water to the members of the GVID. Additional water supplies would allow GVm irrigators to grow more high value crops which are dependent on a reliable water supply. The project would also reduce periodic crop failures which occur due to water shortages. Economic evaluations conducted for this Phase VI study indicated that the cost of crop failures can be significant. Crop failures can cost the GVm members from approximately $100,000 (at a two-year recurrence interval) to over $17 million (at a 25-year recurrence interval or greater). The average annual expected cost of crop failures without any further development of additional irrigation supplies is approximately $1.5 million. The present value of these average annual costs, assuming a four percent discount rate over a 50-year period, is over $34 million.

Under current conditions crop failures occur periodically due to insufficient precipitation in April and May. This generally occurs before the Sunshine Reservoirs can begin releasing water. Crop failures can also occur when there is not enough late season irrigation water in August and September to "finish off" beans, sugar beets, and other high value crops. Hence, because there is a greater risk associated with growing these crops, many farmers elect to plant less risky, lower value crops such as alfalfa. The Greybull Valley Dam and Reservoir project would increase the water supply available to the farmers and dramatically reduce the economic risk associated with periodic water shortages.

A secondary, but extremely important, benefit of the project will be more efficient use of the existing water available in the watershed. The headwaters of the Greybull River and its major tributary, the Wood River, are located in the Absaroka Mountains, over 20 miles upstream of the diversions to Upper Sunshine and Lower Sunshine Reservoirs. Mountain snowmelt is the primary source of water in the Greybull River during the spring and summer months. In addition, the diversion to the Farmers and Bench Canal systems is located over 35 miles downstream of Lower Sunshine Dam, where existing irrigation water deliveries are made. Hence, because of snowmelt, precipitation, other diversions, and return flows between the headwaters and the diversion to the Farmers and Bench Canal systems, diurnal flow variations in the Greybull River are very high. Daily flow variations can commonly exceed 400 to 500 cfs during the average irrigation season. These extreme river fluctuations, combined with the long distance and delivery time between water supply and end user, make it extremely difficult to deliver water to the present users. A great deal of available water is currently wasted because it cannot be captured and delivered for beneficial use at the appropriate time during the day or the growing season.

94071\REPOR1\TEXT.VI 2-2 200,000 ································1,····································1... ····································1.,··········· .. ········ .. ······· .. ··1.,,···· ...... 1" ...... ··········T···································"!··································.. f···························_······r···································1 .. ······· ...... !

i I I I I j : I --- Average Flow at Meeteetse Gage ! . I 180,000 ...... +.... ······· .. ···················l .. ····· .. ·············· .. ···········~··································r·································r ·· .. ···,·· .. ······ .. ····· .... ··············1 ---0-- Wet Year Flow at Meeteetse Gage i i i i 160,000 -+- Dry Year Flow at Meeteetse Gage ...... ····· .. ·r·· .. ····· .. ······ ·········· .. ··-r····· .. ··············· .. ·.. ····· .. r······· .. ·················· .. ····r········ .. ··· .. ········ .. ·.. ····T .. ·...... _...... :

140,000 I L-_·_-.,..-g_:_~_a~_~_~~_e-:-~s_e:o_o~_F_a_rm-,--e_rS_&_B_e_nc-.-h--1 ...... ················i--·················· __ · ;··-···-···········+~;~~~,f~;~~~i~·~··i~~ortag~~····· ········--1

120,000 ...... ;. .- ...... ~-...... ~ ...... -.. ·····················f····································f················· ················t······························· .... t···································1 ...... :...... -...... ~ t-w W LL w• 100,000 ./-...... ; ...... / ...... ~ ...... -.... ~ [I: 0 ~ ...... -...... [...... [ ...... "/" ,··+· .. ·······+ .. ·.. ···· .... ·· .. ·.. i'· ...... · ...... ·· ...... ·,;...... !...... _._ ...... : 80,000 i i : : : . ! f

.. ~...... ~ ...... -...... ~ 60,000 i i i ~"" i i It) --r-l

~ :. : : o . . i 40,000 ...... 1' ...... ···········1····································1 '"C) it --r-r-! ! I ; It ..., ·.A;·············i.... ········ .. · .. ··"""·············:········ ...... : I 20,000 ~ ; i S ~ ~ 0,000 ~ -..J ~ Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec ~ ~ ~ E WWDC /GVID ~ GREYBULL VALLEY PROJECT COMPARISON OF MEETEETSE C) CHEYENNE, WYOMING FLOWS VS. LOWER RIVER ! LEVEL II - PHASE VI IRRIGATION DEMANDS ~ L-______~~~~~~~~~~~~ ~ GEl Consultants, Inc. ______PROJECT NO. 94071 ~ ______MAY. 1994 ~ FIGURE ______2.3 ~ The location of the project with a large diversion canal capacity to capture excess flows during high run-off periods of the day and the ability to make timely water deliveries from a reservoir located within five miles of the Farmers and Bench Canal diversion would eliminate much of the existing water waste. Providing timely delivery of the appropriate amount of water is very important for the successful production of many crops in the Greybull Valley. This is especially important for dry beans, which are particularly sensitive to over- and under-applications of water. As a result, there would be crop yield increases attributable to the project even if there were no increase in water supply. Although not yet quantified, the ability to more efficiently re-regulate the river system may also provide additional project benefits to recreation, fisheries, water quality and other resources in the basin.

It is also important to understand that a significant amount of the river flow downstream of the Town of Meeteetse results from return flows from upstream irrigated lands. Previous studies have indicated that these return flows are significant during the winter months and may exceed 20,000 acre-feet in an average year [Bereman, 1989]. Return flows in this area of the river have increased significantly since the construction of Upper and Lower Sunshine Reservoirs [GEl, 1994-2], Hence, a t,hird benefit of the project is the ability to capture and store a substantial portion of these return flows during the non-growing season for use during the irrigation season when demands are highest.

The need for additional water in the Greybull River watershed is also evidenced by the irrigators' ability and willingness to pay for supplemental supplies. The GVID will finance its portion of the project costs by selling storage shares in a new project. Previous economic evaluations indicate that GVID members are willing to purchase up to 20,000 one-acre-foot storage shares at a price of approximately $21 per share per year [GEl, 1994-2]. In addition, the GVID already has commitments for over 18,000 one-acre-foot shares. Previous studies have also indicated that at prices less than $21 per acre-foot the demand for additional shares increases dramatically and that a 30,000 acre-foot reservoir will meet the demand for additional water supplies. A 30,000 acre-foot Lower Roach Gulch Reservoir, developed with a 1,000 cfs water supply canal, will provide an additional yield of approximately 26,500 acre-feet of water on an average annual basis.

94071\REPORTITEXT. VI 2-3 2.2 PURPOSE & NEED

The purpose and need for the project can be summarized as follows:

The purpose of the Greybull Valley Dam and Reservoir Project is to provide supplemental lower basin storage of water that can significantly reduce crop failures and increase crop yields. Lower river basin storage will also provide river re-regulation benefits that will reduce current water waste by providing more timely delivery of water to the majority of the irrigated lands and provide the ability to capture return flows for beneficial use during the non­ irrigation season. Approximately 30,000 acre-feet of supplemental irrigation water are needed to meet the sponsor's current demands for supplemental water.

The Greybull Valley Dam and Reservoir project may also have the potential to provide secondary benefits to fisheries, wetlands, recreational resources, water quality and the local economy. Evaluation of these other issues is beyond the scope of this study and can be addressed in future EIS studies.

94071\REPOR1\TEXT. VI 2-4 This section describes the development of alternative projects which were evaluated in an initial screening process to develop primary alternatives for consideration during EIS scoping. The locations of these alternatives are shown on Figure 3.1.

3.1 PREVIOUS STUDIES

Alternative formulation began with a review of previous studies in the vicinity of the project made available by the WWDC and the GVID. Solutions to the water resources challenges in the Greybull River watershed have been studied by a variety of organizations since the late 1950s. One of the most comprehensive summaries of previous similar work is provided in a 1988 WWDC report entitled "Guidebook for Water Resources Management and Development for the Bighorn and Clarks Fork Basins" (Guidebook), [HDR, 1988]. Several proposed water resources projects were summarized that would have the potential to reduce or eliminate the GVID's water supply shortages.

The majority of the projects described in the 1988 Guidebook were not pursued due to poor economic feasibility or insurmountable technical, institutional, or environmental issues. These projects have generally been considered as secondary alternatives in our evaluations. However, some of these projects were considered in our initial screening as shown in Table 3.1. A significant conclusion in the 1988 Guidebook was that non-structural solutions such as exchanges, irrigation system rehabilitation, groundwater recharge, and drainage projects will not reduce the water supply challenges in the basin without providing structural storage projects that can store higher flows for supplemental irrigation deliveries.

Another significant planning effort in the basin is summarized in a 1989 study by John S. Bereman and Company. Bereman identified twelve reservoir sites in the reach of the Greybull River downstream of the Town of Meeteetse and upstream of the community of Otto. The upper limit of the study was established as a location where significant return flows enter the river from upstream irrigated lands and the lower boundary was set as the farthest downstream location where a reservoir could serve a considerable acreage of the GVID by gravity flow. Bereman screened the original twelve dam sites to six projects located at five sites. His screening was based on difficulties in constructing a water supply canal to the off-channel reservoirs or because reservoirs with a minimum storage capacity of 20,000 acre-feet could not be developed at the specific site. Bereman's primary project alternati ves were as follows:

• Lower Roach Gulch Dam • Blackstone Gulch Dam • Middle Roach Gulch Dam • Blackstone\McGee Gulch Dam • Upper Roach Gulch Dam • Sheets Flat Dam

94071\REPORl\TEXT.VI 3-1 o- --6 12- 18 SCALE- IN MilES tEGEND PRO.£CT CANAl AL TERNA n'tCI GREYBUlL RIVER BASIN BOUNDARY

.~--... - EXIS~ RIVERS. CREEKS AND CANAlS HIGHWAYS .. /' .,~' .,- '~"",-- .. , • TOYIHS ,/ CIn-V."'" VA" _V DAM I\NA EXlS~ RESERVOIRS ,f'tI A .....VOlA PA0:4-CT ~ PRO.£CT RESERVOIR ALTERNAnVES / PLAN OF AL lERNAliVES --... /' _ OAEGON ~ AREA WWDC /GVID CHEYENNE, WYOW'NG GREYBULL VALLEY PROJECT PLAN OF INITIALLY LEVEL II .- PHASE VI EYALUA TED AL TERNA liVES ~L-______~111=3=~:~~G~E~1_c~o~n~S~U~l~ta~n~U~.~ln~C'~L~-_-_-_-_P:RO:J:E:C:T::NO:.::9:40:7:1:::~~::W:AY::1:9:9:4:::F:IG:U:R:E::::a~1 Bereman's analysis indicated that construction of a reservoir with a storage capacity of up to 30,000 acre-feet was justified in this reach of the river. He also estimated that return flows provide the opportunity to divert an average flow of 70 cfs during the months of November through March [Bereman, 1989]. Hence, an average annual yield of approximately 21,000 acre-feet could be expected from these winter return flows. Bereman concluded that the most feasible alternative would be a dam site in Roach Gulch.

Bereman's report focused previous Level II studies funded by the WWDC on first the Upper Roach Gulch Dam and Reservoir site, and later on the Lower Roach Gulch site. The lower dam site is preferred by the WWDC and Gvm to the upper dam site due to technical concerns [GEl, 1991-2]. The location of the lower project is shown on Figure 3.1. Significant features of the project include a diversion dam on the Greybull River downstream of Meeteetse with a capacity to divert up to 1,000 cfs through a six-mile-long water supply canal to the Lower Roach Gulch Reservoir site. The reservoir would be created by the construction of a 150-foot-high, zoned-earth embankment dam with a storage capacity of 30,000 acre-feet.

Previous Level II evaluations for this project were completed by the GEl and SWWRC team and are described in greater detail in the Phase V report [GEl, 1994-2]. These studies can be summarized as follows:

• Phase I: Draft feasibility study of the Upper Roach Gulch Dam site [GEl, 1991-1].

• Phase II: Draft feasibility comparison of 35,000 acre-foot reservoirs at the Upper and Lower Roach Gulch Dam sites with a water supply canal designed to convey 500 cfs. The lower site was selected over the upper site by the WWDC due to technical concerns [GEl, 1991-2].

• Phase III: Draft feasibility design of a 25,000 acre-foot Lower Roach Gulch Reservoir with a 500 cfs water supply canal at a lower alignment [GEl, 1992].

• Phase IV: Evaluation of alternative financing under the U.S. Bureau of Reclamation's Small Reclamation Project Act. A systemwide project operations model was developed during this phase. The initial results of the systemwide modeling, willingness-to-pay evaluations and current interest in the project by shareholders confirmed that a 30,000 acre-foot Lower Roach Gulch Reservoir was the sponsor's preferred project configuration. A 1,000- cfs water supply canal was also included in this configuration because its river re-regulation benefits were determined to be well worth the incremental investment in additional capacity. The yield at the preferred project configuration was determined to be approximately 26,500 acre-feet [GEl, 1994-1].

• Phase V: Conceptual design report for the project defined during the Phase IV evaluations [GEl, 1994-2].

94071\REPORT\TEXT.VI 3-2 TABLE 3.1 SUMMARY OF PREVIOUSLY PROPOSED ALTERNATIVES

Sheets Flat Dam Bereman, 1989 Yes Similar to Mainstem Dam Site A Lower Roach Gulch Dam Bereman, 1989 Yes Middle Roach Gulch Dam GEl, 1991-2 No Similar to, but more expensive than, Lower Roach Gulch Upper Roach Gulch Dam GEl, 1991-2 No The Lower Roach Gulch was a technically superior dam site Blackstone Gulch Dam Bereman, 1989 Yes McGee Gulch Dam Bereman, 1989 No Similar to, but more expensive than, Blackstone Gulch Dam Rawhide Creek Dam HDR,1988 Yes Lower Greybull Watershed HDR,1988 No Does not provide increased Project water yield Shoshone Extension South HDR, 1988 Yes Transbasin Diversion Project Meeteetse Reservoir HDR,1988 Yes Similar to Mainstem Dam Sites B, C, D, & E Spring Creek Dam HDR,1988 Yes Wood River Reservoir HDR,1988 Yes Similar to Mainstem Dam Site F Clarks Fork Diversion HDR, 1988 No Very costly and complex Diversion to Gooseberry Creek HDR,1988 No The project would increase GVID shortages System Improvements HDR,1988 Yes Considered in conservation alternative Groundwater Recharge HDR,1988 Considered in groundwater alternative

3.2 CRITERIA FOR THE FORMUlATION OF ALTERNATIVES

Eighteen alternatives to meet the sponsor's purpose and need were initially considered for evaluation under a two-stage screening process. These alternatives were developed to provide the full range of practicable solutions to Greybull Basin water shortages based on previous studies and discussions with the WWDC and GVID. The intent of the screening was to categorize all projects as either primary or secondary alternatives. Primary alternatives are those projects which, based on GEl's screening described in Section 4, have the potential to meet the sponsor's purpose and need in a reasonable, practical, and cost effective manner. Secondary alternatives are those projects which do not appear to meet this criteria. Hence, it is GEl's recommendation that those projects which meet the screening

94071\REPOR1\TEXT.VI 3-3 criteria be considered by the GVID, WWDC, and lead Federal agency as primary alternatives during future EIS scoping activities.

This initial list of 18 alternatives was reduced to 15 before screening as described in Section 3.3. The original 18 alternatives are as follows:

1) Upper Sunshine Reservoir Enlargement 2) Lower Sunshine Reservoir Enlargement 3) Rawhide Creek Reservoir 4) Spring Creek Reservoir 5) Meeteetse Creek Reservoir 6) Blackstone Gulch Reservoir 7) McGee Gulch Reservoir 8) Lower Roach Gulch Reservoir 9) Mainstem Reservoir Site A 10) Mainstem Reservoir Site B 11) Mainstem Reservoir Site C 12) Mainstem Reservoir Site D 13) Mainstem Reservoir Site E 14) Mainstem Reservoir Site F 15) Transbasin Diversion from the Shoshone River 16) A Conservation Project 17) A Groundwater Supply Project 18) No Action Scenario

Alternative water storage projects were developed for consideration during screening to be comparable with the Lower Roach Gulch Dam and Reservoir project. At the time of the writing of this report, this project is the sponsor's preferred alternative. Previous studies have indicated that it is a feasible project that GVID members are both willing and able to finance [GEl, 1994-2]. Hence, the following feasibility criteria were applied to develop alternative project reservoir configurations that are consistent with the Lower Roach Gulch Dam and Reservoir project:

1) Consistent with Lower Roach Gulch Reservoir, a storage capacity of 30,000 acre-feet should be available at the dam site;

2) Layouts for off-channel dams and mainstem dams (dams on the mainstem of the Greybull River or Wood River) were developed based on typical cross sections shown on Figure 3.2.

3) Off-channel reservoir sites should include a water supply canal with a design discharge capacity of 1,000 cfs.

4) Mainstem dams were sited to evaluate a variety of yields associated with different combinations of drainage areas along the Greybull River. These

94071\REPOR1\TEXT.VI 3-4 25' n CREST ELEVATION

50' - SITE A ESTIMATED ORIGINAL 30' - SITE B THROUGH F GROUND SURFACE l£J TYPICAL SECTION - MAXIMUM HEIGHT MAINSTEM DAM SITES (NOT TO SCALE)

25' n ~DAM CREST ELEVATION 100' 40' I" H/2

H/4 ESTIMATED ORIGINAL .--~---+- GROUND SURFACE ~

TYPICAL SECTION - MAXIMUM HEIGHT OFF-CHANNEL DAM SITES (NOT TO SCALE)

WWDC / GVIO GENERAL OFF-CHANNEL 1. SADDLE DIKES, IF REQUIRED CHEYENNE, WYOMING GREYBULL VALLEY PROJECT CONSIST OF 3H:1V UPSTREAM ~~ ______--I AND MAIN STEM DAM LEVEL II - PHASE VI AND DOWNSTREAM SLOPES. CROSS SECTIONS dams were also located to represent similar previously studied projects in the basin [HDR, 1988].

5) Consistent with Lower Roach Gulch and Level II, Phase I water resources systems modeling, dam outlet works must be able to provide an additional discharge capacity of 500 cfs beyond existing capacity [1991-1]. This is also the approximate capacity of the Farmers and Bench Canal diversion. This criteria resulted in the assumption of a 500 cfs an outlet works capacity for off-channel reservoirs and an additional 500 cfs capacity for enlarged reservoirs. Mainstem dam sites were developed with a discharge capacity of 1,000 cfs.

6) Spillway configurations were estimated to be capable of safely passing approximations of the Probable Maximum Flood (PMF).

Consistent with alternative evaluation guidelines described under the CEQ regulations (40 CFR 1500-1508) and 404(b) of the Clean Water Act and in an effort to illustrate the full range of reasonable and practical alternatives to meet the sponsor's purpose and need, some non-storage alternatives were also considered. These projects include the Shoshone River trans basin diversion, a groundwater project, and a conservation project. In addition, NEP A requires that a No Action alternative be evaluated in the EIS. Hence, the No Action scenario was included in the screening process.

It is important to note that the development of alternatives and subsequent comparative analysis were based on GEl's experience with similar water resources projects and were not performed in a public forum with the input of a diverse group of project stakeholders. Once the EIS process begins, additional alternatives may be developed, or alternatives described herein may be reclassified as either primary or secondary alternatives. With the exception of the No Action scenario, all alternatives reported in this document are considered to provide independent solutions to the existing water supply challenges facing the GVID. The development of alternative combinations or systems of projects was beyond the scope of this study, but may be required in the EIS.

3.3 INITIAL ALTERNATIVES THAT WERE NOT CONSIDERED

Three of the originally considered 18 alternatives were not considered in our screening process and have subsequently been categorized as secondary projects. These include the Meeteetse Creek Reservoir, enlargement of Lower Sunshine Reservoir, and all combinations of the McGee Gulch Reservoir.

The Meeteetse Creek Dam site cannot provide 30,000 acre-feet of storage capacity. In addition, a water supply canal in excess of 20 miles in length would be required to provide a project water yield that was comparable to other storage projects. It was determined that it would likely be cost prohibitive to consider a canal of this length.

94071\REPOR1\TEXT.VI 3-5 There are significant technical feasibility and dam safety issues associated with raising Lower Sunshine Dam. There is very high seepage in the sandstone and shale foundation and abutments at Lower Sunshine Dam which has been a historic concern of the Wyoming State Engineer. Remedial grouting programs have previously been attempted to reduce this seepage with limited success. Raising the dam would increase water pressures on the foundations and abutments by approximately 26 feet. This additional seepage pressure could create dangerous conditions at the dam which could threaten overall downstream human health and safety. Hence, at the time of the writing of this report, the enlargement of Lower Sunshine Dam has been classified as a secondary alternative -and no additional engineering evaluations have been pursued.

McGee Gulch and Blackstone Gulch are adjacent drainages in which the respective mouths of each drainage are less than a mile apart. Bereman' s evaluations included a project with combined dams on both Blackstone and McGee Gulch with the capability of storing up to 80,000 acre-feet of water. The combined project was not initially considered for screening because previous studies indicated that this is more water than the GVID can sell to its membership and it provides more water than is currently required during an average year [GEl, 1994-2]. The Blackstone dam site is capable of providing up to 30,000 acre-feet of storage independent of a dam on McGee Gulch. It is also closer to the Greybull River which would require a shorter water supply canal and it appears to be a better dam site located in a narrower valley. Both sites are located very close to each other and represent essentially the same project, but Blackstone Dam will likely be more economical. For this reasons, no engineering evaluations were performed for McGee Reservoir and it was not considered during screening.

3.4 DESCRIPTIONS OF ALTERNATIVES CONSIDERED FOR SCREENING

3.4.1 Enlargement of Upper Sunshine Reservoir

Upper Sunshine Dam is an existing zoned-earthfill dam located in Section 12, T.47N., R.1 02W. The dam is approximately 150 feet high and would need to be raised approximately 23 feet to provide an additional 30,000 acre-feet of storage as shown on Figures 3.3, 3.4, and 3.5. This alternative would require: 1) the placement of additional fill on the crest and downstream slope of Upper Sunshine Dam; 2) removal and reconstruction of the existing saddle dike near the spillway on the left reservoir rim; and 3) construction of an additional saddle dike and 150-foot-wide, trapezoidal-shaped, excavated earth spillway channel in this area. This would require over 800,000 cubic yards (cy) of earthwork. In addition, the existing outlet works conduit would likely need: 1) to be extended and relined with steel pipe; 2) a new upstream gate and downstream valve house and valves; and 3) channel improvements to allow for increase discharge capacities in Sunshine Creek. It is also evident that the existing capacity of both the outlet works at Upper and Lower Sunshine Dams would need to be increased by approximately 500 cfs to provide comparable water delivery capabilities with the Lower Roach Gulch Dam. We have assumed that a 2,500-foot­ long, nine-foot-diameter tunnel could be constructed under Upper Sunshine Dam to provide

94071\REPOR1\TEXT.VI 3-6 MATCHllNE

- ~ I I

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WL65Bl

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-I ~ ~ "- ~ .~ MATCHLINE i ~ ~ PLAN ~ WWDC /GVID GREYBUll VALlEY PROJECT ENLARGEMENT OF UPPER o 1000 2000 4000 6000 CHEYENNE, WYOWING I ------LEVEL II - PHASE VI SUNSHINE RESERVOIR 6: SCALE IN FEET ~ PROJECT NO. 94071 WAY 1994 F'lGURE a3 " II GEl Consultants: Inc. 6800 £ EXISTING 6800 I EMBANKMENT I ~ ENLARGEMENT c I DAM AXIS c:i >: 6700 6700 >: EXISTING CREST, I 30' RAISED CREST, o ~ z EL. 6605.5] EL. 6628 z ~""""-::::---_---£-r 6600 -'----.J;,,"""'" 6600 ,-... ,..... I­ RAISED EMBANKMENT I­ UJ UJ UJ UJ lL.. lL.. '-" ~EL. 6482 '-" z 6500 6500 z o ~~~~~~---r--~~~~~~~ o ~ ~ > > ~ 6400 6400 ~ UJ UPPER SUNSHINE DAM ENLARGEMENT UJ TYPICAL EMBANKMENT SECTION 6300 6300 o 100 200 400 I I SCALE IN FEET 6700 6700 't SADDLE DAM AXIS ci I ci >: 6650 30' EL. 6628 6650 :> ~ ~ z z

,-... 6600 6600 ,-... I­ I­ UJ EL. 6558 UJ UI UI lL.. lL.. '-" '-" z 6550 6550 z o o i= i= -< < 'I'- > > ~ ~ 6500 6500 ~ s UI UPPER SUNSHINE DAM ENLARGEMENT UI 6450 TYPICAL SADDLE DIKE SECTION i 6450 '-J :5 o 50 100 200 ~ I I ~ SCALE IN FEET E ~ WWDC / GVID GREYBULL VALLEY PROJECT CROSS SECTION OF _(3 CHEYENNE, WYOMING ENLARGED It - LEVEL II - PHASE VI UPPER SUNSHINE DAM ~ ~ GEl ConsuUant~ Inc. ~~-P-R-O-J-EC-T~N-O-.~9-4-0-7-1~~~M-A-Y~1-9-9-4~TF-I-G-U-R-E~~3-.4~ ~------~~~~~~~~~~~~~------~------~~------6650

6625 N.W.S. ENLARGEMENT, EL. 6618 ... _ ... _ ... _ ... _ ... _ ... _ ... _ ... _ ... _ ... _ ... _ ... _ ... _ .. . _ ... -;;r-r-- c -> -" -- (,!) -- 6600 N.W.S., EL. 6595 = 53,515 A.F. __ -,,--- z, .-.. 6575 .-w W '-'"La.. 6550 z o .- u: ~ < 6525 .( .( >w ...J &I') &I') W -&I') ...... &I') 6500 ttl 1 ttl I &1')1 001 I I I I I I I I 6475~--~----~--~----~--~~'--~--~----~~'~--~ o 1 0 20 30 40 50 60 70 80 90 100 ACRE-FEET (x1000) UPPER SUNSHINE RESERVOIR 6325

N.W.S. ENLARGEMENT, EL. 6303 _ c ... _... _ ... _... _... _... _... _... _... _... _ ... _... _... _... - ... ~- 6300 ,,--" > ,," (,!) ,," z N.W.S., EL. 6277 = 56,378 A.F. ,,",," 6275 .-...- w w 6250 La.. '-'" Z 0 6225 ~ ~ ~ ~ .- .( .( Ii) < > OJ 00 -.!!. w ...J ,." 0 w 6200 ""'!.I " .... (01 tOl C) &1')1 OJI I I I I ~ I I I I a: I I 6175 I I Ii) I ~ 10 20 30 40 50 60 70 80 90 S. o § STORAGE CAPACITY ~ ACRE-FEET (x1000) ~ ..... ~ ~ LOWER SUNSHINE RESERVOIR ~G~ ______~ ______~ ______~

~ WWDC / GVID GREYBULL VALLEY PROJECT UPPER AND LOWER C) CHEYENNE, WYOMING SUNSHINE RESERVOIR !t-_-_-_------1 LEVEL II - PHASE VI AREA-CAPACITY CURVES ~~GID~n~R~~fu~~---P-R-O-J-EC-T--N-O-.-9-4-0-7-1----~-M-A-Y--1-9-9-4~~F-IG-U-R-E-----a~5 this additional capacity. A similar tunnel would be required under Lower Sunshine Dam in order to match the release capacity of Upper Sunshine Dam. Finally, the existing Sunshine Diversion Dam and Canal would need to be enlarged and reconstructed to provide an additional water delivery capacity of 1,000 cfs which is comparable to the Lower Roach Gulch alternative. The upper 5.5 miles of canal section can be enlarged to provide a total discharge capacity of 2,000 cfs. The lower two miles of canal would need to be reconstructed to allow delivery to Upper Sunshine Reservoir at the higher reservoir water surface elevation.

3.4.2 Rawhide Creek Dam

The Rawhide Creek Dam site is located approximately 3.6 miles upstream of its confluence with the Greybull River in the eastern half of Section 7, T.48N., R.lOlW. as shown on Figures 3.6.1 and 3.6.2. A l50-foot-high, zoned-earth embankment dam with a crest length of approximately 1,500 feet at approximately elevation 6460 would be required to store 30,000 acre-feet at this location. In addition, a 3,000-foot-Iong saddle dike with a maximum crest height of 50 feet would be required on the southern rim of the reservoir. It is estimated that the PMF could be safely routed through a 200-foot-wide, trapezoidal-shaped, excavated earth spillway located on the right abutment of the dam. Rawhide Creek would need to be stabilized between the dam and the Greybull River to prevent erosion at higher discharge rates. The project would also include a new diversion dam and a 7.3-mile-Iong water supply canal to deliver water from the Upper Greybull River to the reservoir.

3.4.3 Spring Creek Dam

This alternative is on Spring Creek approximately 2.7 miles upstream of its confluence with the Greybull River as shown on Figure 3.7. The dam would be located in a narrow valley in Section 1, T.48N., R.lOl W. A 30,OOO-acre-foot reservoir could be created at this site by constructing a zoned-earth embankment dam with a maximum height of approximately 215 feet. The dam's crest would be approximately 1,600 feet long at elevation 6090. No saddle dikes would be required and a l50-foot-wide, excavated earth spillway could be constructed on the left abutment of the dam. A new diversion dam and a l6-mile-Iong water supply canal would be required to deliver water from the Upper Greybull River to this reservoir site in order to provide water supplies in sufficient quantity to meet the needs of the GVID.

3.4.4 Blackstone Gulch Dam

It is apparent that the Blackstone Reservoir site was considered as a secondary alternative in Bereman's evaluations due to the difficulty of constructing a water supply canal to the reservoir. GEl concurs with the difficulties of canal construction at this site as shown on Figure 3.8, but we have developed what could prove to be a feasible concept to divert water from the Greybull River to the reservoir. This includes a two-mile-long diversion system that features approximately one mile of canal and a mile of l3-foot-diameter, concrete-lined tunnel. The tunnel could be constructed through sandstone, siltstone, and clay shales in the

94071\REPORTITEXT.VI 3-7 MATCHLINE

MATCHllNE -.1'LAN o 1000-- 2000 4000 6000 -- SC,t,LE- IN FEET

WWDC /GVID CHEYENNE, WYOMING GREYBULL VALL£Y PROJECT OFF-CHANNEL RESERVOIR LEVEL II - PHASE VI RAWHID! CREEK

~ ______,______~~~~~~~~~I~n~c.WL __~P~R~O~JE~C~T~NO~.~I~40~7~1 __-L-=MA~Y~1~99~4~~F~I=G~UR=E~3=.=e.~1 6550~------

6500~·························;······················· ... ;...... ;...... ~ ...... ~ ...... ~ ...... ~ ...... ;························1

-.::- 6450 -I ...... :...... ;...... L ...... ~ ...... ;...... L_...... -- ...... =L_------~~--- tj ....-----....------~ ~~ 5 6400 ..v- ~ L ..... ~ 6350-V

6300'·························,······················· .. ~ ...... ;...... ·~·························i··························; •...... •..••.•.•••...••.~ .•••••.•.•••.•••••.•••••• ·~·························I

6250~----r----+----~----r-1---+----~----~--~--~ o 5000 10000 15000 20000 25000 30000 35000 40000 45000 VOLUME (ACRE-FEET)

CREST EL. 6460

6450 ···-:···-···r···_···_···-···-···_··· L NORMAL POOL EL. 6440

6400 -t; UJ ~ '-" z o ~ < >UJ "'" ...J ~ Ie) 6350 UJ -.!!.

•t..... ~ a:~ <\j I ~ 6300 I <3 0+00 10+00 20+00 S. r::: STATION <::) ~"'" ooJ ;5 PROFILE - MAIN DAM ~ ~ Gr------~~------~------~ ~ WWDC / GVID GREYBULL VALLEY PROJECT <::) CHEYENNE, WYOMING OFF-CHANNEL RESERVOIR !~-~~~------~ LEVEL II - PHASE VI RAWHIDE CREEK ~ ~ GEl Consultants. Inc. PROJECT NO. 94071 MAY 1 994 FIGURE 3.6.2 8100

".- ~ ~ ~ / V / ~ f

o 5000 10000 15000 20000 25000 30000 35000 40000 4SOOO \Q.UME (ACRE-FEET) ELEVATION - VOLUME CURVE

CREST EL 6090 .6100

··-··~···-···--···l···-···-···-···-···-···-··· NORMAL POOL EL. 6074 6050

PROFILE - MAIN DAM

PLAN ~------~~------~~ 0+00 10+00 20+00 o 1500-- 3000 6000 9000 - SCALE- IN FEET 1- ' \ 5250 /! I I I I I ! I i I I I I I 5200 ! (~---- -~·-W I - I i I I -t:i I ...... ,. I ! I I I I! ~ 5150 III" I I - i I ( -~ I I F= I; 5100 ~ ! I ~ I i I( I

~ I I I I I I 5050 i I I I i I i I ! i I I I I 5000 I I I I o 5000 10000 15000 20000• 25000 30000 35000 40000 45000 \Q.UME (ACRE-FEET) ELEVATION - VOLUME CURVE

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5200

"'-"'~'"-'''1''-'''-'''-'''-'''-''' ~ NORMAL POOL - EL. 5181 ~ 5150 - ~ F= ~ ~

5100 ... .!!. • PROFLE - MAIN DAM r------~~------~505O 0+00 10+00 20+00

PLAN o 1000 2000 4000 6000 ------WWDC /GVID SCALE IN FEET CHEYENNE, WYOMING GREYBUll VAU.£Y PROJECT OFF-CHANtEL RESERVOIR LEVEL II - PHASE VI BLACKSTONE GULCH ~~ ______, ______~-_:lE_i_~~G~E~1~C~O~n_IU_l~W_n_~ __ ~ln_C~.~~-~_-_P:R:O:J~E_C:T:~N_~O_-._~'_40::7:1::::::MA:-Y_-_1:9:9-4_-_~~~F:I-G~U~R:E::-~~-8~-4~ left abutment of the reservoir. The project diversion dam would be located approximately two miles upstream of the location of the Roach Gulch Diversion.

A 30,000-acre-foot reservoir could be created with a 115-foot-high, zoned-earthfill dam located at the mouth of Blackstone Gulch in the eastern half of Section 12, T.50N., R.99W. The crest length of the dam would be approximately 1,400 feet in length at elevation 5190 and two small saddle dikes less than 15 feet in height would be necessary on the right reservoir rim. A 150-foot-wide, trapezoidal-shaped, excavated earth channel spillway could be located on the right abutment of the dam and a 7,000-foot-long, excavated earth channel would be required to discharge water from the outlet works back to the Greybull River.

3.4.5 Lower Roach Gulch Dam

Conceptual designs have been previously developed for the Lower Roach Gulch Dam and Reservoir during Level II, Phase V evaluations [GEl, 1994-2]. The dam shown on Figure 3.9 would be a 150-foot-high, zoned-earth embankment dam with a crest length of approximately 1,700 feet at elevation 4950. The dam site is located mainly in the southwestern quarter of Section 23, ~.51.N., R.98.W. A 150-foot-wide, excavated earth channel spillway would be located on the left abutment of the dam and a 1,100-foot-Iong, excavated earth channel would be required to discharge water from the outlet works back to the Greybull River. Water would be delivered to the reservoir via a six-mile-long water supply canal.

3.4.6 Mainstem Dam Site A

The mainstem dam site A shown on Figure 3.10 is essentially the same configuration as the Sheets Flat Dam identified by Bereman. A 30,OOO-acre-foot reservoir would require a 110-foot-high, zoned-earth embankment dam located in Section 21, T.51N., R.98W., approximately five miles upstream of the Farmers and Bench Canal Diversion Structure. The dam crest would be approximately 5,000 feet long at approximately elevation 4,950. A 700-foot-wide, concrete overflow spillway would be required to pass the estimated PMF.

3.4.7 Mainstem Dam Site B

Mainstem dam site B would be located within a mile upstream of the Town of Meeteetse in Section 8, T.48N., R.100W. A project in this vicinity was considered at one time by the GVID, but was eventually abandoned in favor of the Lower Sunshine project. The site B dam shown on Figure 3.11 would be approximately 130 feet high with a crest length of approximately 3,600 feet at elevation 5930.

A 700-foot-wide, concrete overflow spillway would also be required to pass the estimated PMF associated with a 30,000-acre-foot reservoir located at this site.

94071\REPOR1\TEXT. VI 3-8 5000~----~--~----~--~----~----~--- CREST EL. 4950 ci 5020 > 4950 ...... NORt.AAL POOL, ci EL. 4946 Z I 4940 I- 4900 ...... -LaJ LaJ I.&.. ,...... I­ 4860 z ..... 0 ...... ~ 4850 ...... f= ~ ~ 4780 ~ f= LaJ ~ 4800 ...... ~ ..... 4720 4750

j I 4660 4700~----r----T----+----;----~----~--~ 0+00 10+00 20+00 o 10000 20000 30000 40000 50000 60000 70000 PROFILE_ VOLUt.AE (ACRE-FEET) ELEVA liON - VOLUME CURVE

"

.... ! •

PLAN WWDC /GVID 1500 3000 6000 9000 CHEYENNE. WYOWING GREYBUU VALLEY PROJECT OFF-CHANNEL RESERVOIR o------~~ ______S_C_A_L_E_I_N_F_E_E_T ______~=1II=:~:~~G~E~I~C~O~n~8~ul~t~an~U~.~In~C~ ..r~_-_-~~!R~;:~~E~C~I~~:-~N:~O~P_.~H~:~~:a:E~7~:~I __ ~_~~_-!M~:~::~~1-9~:~4_R~OjjA~_:~_~~G~:~:_E~L:C!:_.~.:j ~,---~----!.----~---.----r---~--~----~--__ : i t; ! I

~ 49~~----4!----~.·r ---'l-~::t:::~~--t---~~~~---iI ; ....~ i I ..I r-. i ! ~ 4900 .----i-- __-!- __+- __+ ! ____.~ ______~ ! ____L - ! ; I I - ! ! ! i d ! i i ! .-L-_+.----L_--L-_r ' I I ! i ! ! ! i I I i I I I 4800 -t---....,-----+---+----+----i-'---- ...' ----i'..---~,--__I o 10000 20000 30000 40000 50000 60000 70000 80000 90000 VOLUME (ACRE-FEET) ~~~~,',~' ELEVA TION - VOLUME CURVE J.\/,.o ,/' -4860- , -~-;- ~- -::::. "-,' C'

,...... ---..- 30

W.S. EL. 4924 5000 )

CREST EL. 4949 4950

, - ,- - -~·"-···-·"l··-···-··'-···-···-"'-' ,-",-". NORMAL POOL EL. 4924 .. S...... ~ •.... t) /::: ~ "- I w" ,~ ,,0 ~ .. i I~ ~ ~ PROFILE - MAIN DAM i PLAN r------r------~------~------~------~~4800 ~ 0+00 10+00 20+00 30+00 40+00 50+00 f o 1000 2000 4000 6000 WWDC /GVID ---- CHEYENNE. WYO ..ING GREYBULL VALLEY PROJECT MAIHSTEM RESERVOIR ~ SCALE IN FEET ~ LEVEL II - PHASE VI SITE A ~ ~ ,. GEl Consultants. Inc. t--....P.... RO-J .. [.... C~T---N .... O- ....9- .....07..... 1--+-- ..-A-Y-19-9-.-..-F-IG-U-R-E-3-.1-0 .... 6000 I i I ! I ! I i 5950 ------·-t--·---·--·--·t----t---·- ---_.--1,! -_-_. ~ ~ LIJ i I'I ii' i ~ 5900 ------.-.-.t----.---...,..--. '~I . --t-- 1 t -r----,I - : I ~ ! !! ~ I I I I I I • : : : : ~ 5850 -·-·-'T'--·--··----·1-·.. ·-·--·-T-M--.-.-"'t"---.. --... --;--._._._--,...-_._-_._.- ~ ; ! ! it! LIJ iii II i i i j! I I 5800 -.--.---.-.-+.------.--.+-.-----i---+-.-- I I i ! i I i ! i I ! I i 5750 o 10000 20000 30000 40000 50000 60000 70000 VOLUME (ACRE-fEET) ELEVATION - VOLUME CURVE

5950 CREST EL. 5930

---[_ .. - ... - ... -- 5900 NORMAL POOL EL. 5905

• 5800

PROFILE • MAIN DAM

PLAN r------~------,------_r------~------~575O o 1000 2000 4000 6000 0+00 10+00 20+00 30+00 40+00 50+00 - - - - WWDC /GVID SCALE IN FEET CHEYENNE, WYOMING GREYBULL VALLEY PROJECT MAINSTEM RESERVOIR LEVEL II - PHASE VI SITE B II GEl Consultants, Inc. t---P-RO-J-E-C-r-N-O-.-9-4-07-1--f--M-A-Y-1-9-9-4-.....F-IG-U-R-E-3-.1-1 .... CREST EL. 6256

6250 __ 'i7_ ---- 6200 -l------I: , I i NORMAL POOL i i 6150 -i---~---1__--.-.-.--.-+------.I I I ----i-·------r- EL. 6231 i i! !! 6200 ! i ! i iii ! i I Ii' 6100 -1---....1 --.,J£4----t-----f-----t-----+-----I ! 1 j i ~ i i ! LIJ ~ 6050 ... -#-.-{----+--.------~--.--.---.--.~.---.---~-----+:---I I : : : I i - t j ! i i ! 6150 ~ iii i i ~ F= I Ii! ! i ~ 6000 . -·-i----·-,---·---·1·-·--·--·-r--·-----:·--·-~-- ~ i i ! iii LIJ ! ! j i t i 5950 -+--+-----j-----+--+---+-- 6100 ! ! ! i ! i I Iii i 5900 ! 0 10000 20000 30000 40000 50000 60000 70000 VOLUME (ACRE -FEET) ELEVATION· VOLUME CURVE rl------r------r------~------~6050 0+00 1(HOO 20+00 30+00 40+00 ... ~ PROFILE • MAIN DAM ! ~\ I' ~ __ . ___ • - r~_ -I~ -:----hH+-.-t+------'-"---....,...-!f':---t.~r__-I__~~.._.f_~~~!JIf

Ii \ h/-10. gI i i PLAN ~ o 1000 2000 4000 6000 ~ WWDC /GVID ~_ SCALE IN FEET CHEYENNE. WYO~ING GREYBULL VAu.EY PROJECT MAINSTEM RESERVOIR LEVEL II - PHASE VI SITE F

~ ______~~~~~~~~~~ mGEl Consultants. Inc. t--""""P""""R-O-JE~C~T~N ____~~~~~~_L~~~~~ ... O-. -9-...-0-7-1---I~-~-AY-1-9-9- ...- .....F-IG-U-R-E-3.-15-1 ~~~~ 3.4.8 Mainstem Dam Site C

Mainstem dam site C was located near the confluence of the Wood River and downstream of the confluence of Rawhide Creek to take advantage of run-off from this drainage which extends above elevation 10,000. The dam, shown on Figure 3.12, is located in Section 14 and 23, T.48N., R.I0IW. A 30,000-acre-foot reservoir would require a dam approximately 150 feet in height and its crest would be approximately 4,300 feet long at approximately elevation 6120. A 700-foot-wide, concrete overflow spillway would also be required at site C.

3.4.9 Mainstem Dam Site D

Mainstem dam site D would be located in Section 22, T.48N., R.I0IW. below the Greybull and Wood River confluence. A 30,OOO-acre-foot reservoir at this site would be located above the Rawhide Creek confluence and was evaluated for comparison with Site C. This dam is shown on Figure 3.13 and would back water up near the Lower Sunshine dam outlet works. This dam would be approximately 140 feet high and would have a crest length of approximately 4,600 feet at elevation 6155. A 500-foot-wide, concrete spillway would be required to pass the PMF at this location.

3.4.10 Mainstem Dam Site E

Mainstem dam site E would be located on the Greybull River approximately one mile upstream of the confluence of the Greybull and Wood Rivers in Section 21 and 28, T.48N., R.I0IW. A 30,000-acre-foot reservoir in this location would store only excess water from the upper Greybull basin and could not take advantage of run-off from the Wood River. The dam, shown on Figure 3.14 would be approximately 160 feet high and would have a crest length of approximately 2,200 feet at approximately elevation 6237. A 500-foot-wide, concrete overflow spillway would be necessary at this location to pass the estimated PMF.

3.4.11 Mainstem Dam Site F

Mainstem dam site F was evaluated to be comparable to the Wood River Reservoir described in the 1988 Guidebook [HDR, 1988]. The original Wood River Reservoir was to be located upstream of the Wood River Canal and would have provided a water supply for Gooseberry Creek as well as flood control benefits for the Wood River and lower reaches of the Greybull River. Mainstem dam site F is located approximately seven miles downstream of the Wood River Canal diversion dam in Section 27, T.48N., R.I0IW., as shown on Figure 3.15. This lower location was utilized to take advantage of run-off from a larger Wood River drainage than the original Wood River Reservoir. A 30,OOO-acre-foot reservoir at this site would require a 160-foot-high dam with an overall crest length of approximately 3,400 feet at approximately elevation 6256. A 300-foot-wide, concrete overflow spillway was included in this project configuration.

94071\REPOR1\TEXT.VI 3-9 . I, I' 6150,-----~--~----~--~----~--~----~ - 14 i

!: ; '., I 'P 6100 --'--'-'--'-'-r-'--"--'--l-'-'-'--'--'--I -.----,---.--.-.

LU i i W Iii -; 6050 --.--.-.-. -· ....,1,.. --.-- .. --.--.-;-.-.-.---.--t-.--+.---+--r-·-

~< 6000 _. ___ .__ ._._ .. i...; __ . __•• __ . __ ._._._.______i I• W> !! -1---' ~ ~ ~ 1 j I 5950 ------·----·-·+·-----·-----·-1--·-·-·----·-: ---t---._._. j ! i ! ! 1 I ; ! I 1 1 f i i! ~ 5900~----T---~----~----+---~----~--~ o 10000 20000 30000 40000 50000 60000 70000 VOLUME (ACRt-F'EEl) ELEVA TION - VOLUME CURVE

6150

29 CREST El. 6121

.. -"-' '-:-"-"'-"'1"-"'-'"-'''-'''-'''-'''-'''-'''-''' 6100 NORMAl POOL EL. 6095

• 6000

PROf'J f - MAIN DAM PLAN r------r------~------r------~~------~595O 0+00 10+00 20+00 30+00 40+00 so+oo o 1000 2000 4000 6000 -- WWDC /GVID - SCALE- IN FEET CHEYENNE, WYOt.4ING GREYBULL VALlEY PROJECT MAIHSTEM RESERVOIR LEVEL II - PHASE VI SITE C

~~ ______~~~i~:~G~E~I~Co~n=s~u~l~ta~n~~~.~I~n~c~.~ ___P_R_O_JE_C~T __ N~O~._'_40_7_1 ____ L-_t.4_A_Y_1~9~9~4~~!F~I~G~U~R:E~3~.1=2~ ,- , ~ J , r I 1._- ,- - 14 6200 ,-----'i----~--~----~--~----~.----~

!i I II

'P 6150 ---+---+-,-+--+-=:;;;;iii....r~---+-----! i . I&J I I i ~ : I ! ....., ! . I ~ 6100 ----.--~.- _.-.1..-i ;;i ------4----- ~ ! ! 1 iii ~ iii .--_. _ i __.. _ .. ~ 6050 -14'-- __~I ..:----~---+----+I- 1 j i i

1,1 I I 6000 -t------i;-----+----;;----+---+---+----I. 1 1 o 10000 20000 30000 40000 50000 60000 70000 VOlUME (ACRE-F£ET) ELEVA TION - VOLUME CURVE

6200

CREST EL. 6155 29 l ~::. 6150 "1"-' ,-",_ .. ,_ ... _... _" - ' -",-", NORMAL POOL EL. 6130

6050 W~'-[O b_? -,

'- r------~------T------~------~------~6000 0+00 10+00 20+00 30+00 40+00 50+00 PLAN PROFILE - MAIN DAM o 1000-- 2000 4000 6000 - SCALE- IN FEET 62~~----~--~----r---~----~--~----~~:..-__ i

I; 6200 -:::i...... =--t----+---.-t---.---t---. I : ~ I I L&J i i ad i i ~ 61~ --I---t---+----'f----+---r---r-- i i ~ i i ~ ; I ~ 6100 i f-.---I lIJ ! I -J i I lIJ . . ! ! 6295; .. 6050 -.---- +----i---+---+---.--.;.-.--.-.-.----~-.--- ! ! ! i ! ! ! ! I ; ! ! I ! iii 6000~----+---~-----r;----~;-----+;----~;~---i o 10000 20000 30000 40000 50000 60000 70000 VOLUME (ACRE-FEET) ELEVATION - VOLUME CURVE N.W.S.

CREST EL 62.37 6250

"~6226T- 6200 " " p -~ 6150 ~ ~

~ WP-Io 6100 {-,~-,

~------~------~------~605O 0+00 10+00 20+00 30+00 PLAN PROFILE - MAIN DAM o 1000 2000 4000 6000 - - - - WWDC /GVID SCALE IN FEET CHEYENNE, WYOMING GREYBUll VALlEY PROJECT MAINSTEM RESERVOIR LEVEL II - PHASE VI SITE E

~ til GEl Con8ultanta. Inc. PROJECT NO. 9~071 MAY 199~ FIGURE 3.14 ~------~----~~~~~----~------~------~------~ 3.4.12 Transbasin Diversion from the Shoshone River

Previous transbasin diversion projects evaluated in the area have included a diversion from the Clarks Fork of the Yellowstone River to the Shoshone River and then into the Greybull River. This project appears to be a secondary alternative because it is very costly and complex [HDR, 1988]. The diversion from the Greybull River to Gooseberry Creek mentioned in the previous section would only increase current irrigation shortages in the Greybull River. A diversion from Gooseberry Creek into the Greybull was evaluated by SWWRC. However, their conclusion was that there are not sufficient excess water supplies in Gooseberry Creek to consider this concept as a primary alternative.

The data review indicated that the most feasible transbasin diversion project, from a cost perspective, would consist of components of the U.S. Bureau of Reclamation's Shoshone Extension-South project. Applicable components of this project are shown on Figure 3.16 and include a 23-mile-long Oregon Basin Feeder Canal that would deliver water at a rate of approximately 600 cfs to Oregon Basin and a 24-mile-long Dry Creek Canal to convey water to the Greybull River immediately upstream of the Farmers and Bench Canal diversion. The Dry Creek Canal would be designed to discharge 500 cfs which is comparable to the additional outlet works delivery capacity assumed for other storage concepts. The original USBR concept included storage of approximately 120,000 acre-feet in Oregon Basin. Our analysis was based on the assumption that an equivalent of 30,000 acre-feet of additional water could be stored in the recently enlarged Buffalo Bill Reservoir. Therefore, Oregon Basin storage could be eliminated.

3.4.13 Conservation

Conservation of existing irrigation supplies can include more efficient use of the existing water or reuse of the available water supplies. Our development of conservation alternatives was focused on the Farmers and Bench Canal systems where the majority of the water demands in the GVID occur. These systems are shown on Figure 3.17. Reuse conservation is already practiced extensively by the GVID membership. The lower portions of the Farmers and Bench systems are irrigated with an extensive system of collection ditches to capture irrigation return flows from upstream irrigated lands. Hence, several thousand acres of land are already irrigated by reused water.

A 1986 rehabilitation report for the Bench Canal irrigation system states that about 20 percent of the water diverted into the system is lost to canal seepage [SCS, 1986]. Therefore, the goal of our conservation project evaluations targeted elimination of this lost water by lining existing laterals in the Farmers and Bench Canal systems. SWWRC modeled the impact of concrete lining approximately 100 miles of laterals in the Farmers and Bench Canal systems. It was assumed that this work could reduce seepage losses to approximately 10 percent resulting in an average annual water savings of approximately 11,500 acre-feet. The results of our conservation analysis and estimate of project investment are provided in Section 4.

94071\REPOR1\TEXT.VI 3-10 .-aIRE(~ON BASIN FEEDER CANAL

.. -- ... ~ ...

ALO BILL OREGON RESERVOIR BASIN

GREYBtLL RIVER BASIN BOUNDARY ... .",...,. ... .-... / ... ../ "

LEGEND,

GREYBULL RIVER BASIN BOUNDARY •... -. _... __ ...... RIVERS AND CREEKS HIGHWAYS _...... ,...... _ _.. LATERALS AND CANALS

TOWNS

IRRIGA TED ACRES

I)(JSTING RESERVOIRS

OREGON BASIN BOUNDARY o-,- - 8- 12 SCALE IN MIlES

WWOC /GVIO CHEYENNE, WYOMING GREYBUll VAlLEY PROJECT SHOSHONE RIVER LEVEL " - PHASE VI TRAN8BASIN DIVERSION

'"~L- ______~~~~ ______~~~~~~~~~~~GEl Consultants Inc. ______PROJECT NO. 94071 ----~-- MAY______1994 ~FIGURE ______3.18 ~ -. \\

noW ~,.. A..~_ ••• \,rAJ ... ~ .. --" - ~....,. ,.A4

FARMERS AND BENCH CANAL DIVERSION DAM

...

• ~CZ7 ~TTO // ~ (

.---LOWER ROACH GULCH RESERVOIR LEGEND

ANAL TERMINUS ~LL RIVER BASIN BOUNDARY ••• ~ ••• ' JU't'ERS AND CREEKS LOWER ROACH GULCH CANAL HIGHWAYS LATERALS AND CANALS laWNS GREYBULL RIVER ~~• NlCA TED ACRES BASIN BOUNDARY PRO-ECT RESERVOIR Al TERNA nVES

WWOC / GVIO CHEYENNE. WYOWING GREYBULL VALlEY PROJECT FARMERS AND BENCH o, 6, LEVEL II - PHASE VI CANAL SYSTEMS SCALE IN MILES '-i ;;: L-______~==~~~~~~~~ . GEl Consultants Inc. __ ~~~~~~PROJECT NO. 94071 __ _L~~~~~~~~~WAY 1994 FIGURE 3.17 3.4.14 Groundwater

A reconnaissance evaluation of groundwater supplies that have the potential to meet the sponsor's purpose and need has been prepared by SWWRC and is attached as Appendix A [SWWRC, 1994]. SWWRC prepared cost estimates for drilling wells and constructing collection and delivery pipelines for a groundwater project that could provide approximately 11,000 acre-feet of additional irrigation water to farmers in the Farmers and Bench Canal Systems. The unconsolidated quaternary alluvial deposits of the Greybull Terrace and flood­ plain alluvium along the Greybull River, between the towns of Burlington and Otto, appear to have the best potential for groundwater development.

3.4.15 No Action

Our evaluation of the No Action scenario included an economic analysis of the cost of this alternative. This analysis is provided in Appendix B [Watts, 1994]. The analysis performed by Watts and Associates, Inc. indicates that the expected annual cost of the No Action alternative is approximately $1.5 million. The present value of these costs, assuming a four percent discount rate and a 50-year time period, is over $34 million.

No additional supplemental water supplies or reduction in periodic irrigation shortages will occur under this scenario. Hence, it does not meet the sponsor's purpose and need and should not be considered as a viable alternative. However, in accordance with NEPA, a "No Action" alternative must be evaluated in the EIS.

94071\REPORT\TEXT.VI 3-11 This section describes the screening methodology that was used by GEl to perform a comparative analysis of the alternatives. Primary alternatives are those projects which have the potential to meet the sponsor's purpose and need and provide reasonable and practical solutions to the GVID's water supply challenges in a cost effective manner. Secondary alternatives are those projects which do not meet the screening criteria described in this section. Secondary alternatives also include the three projects which were not given any additional consideration because of obvious technical or cost considerations.

After the Meeteetse Creek Dam, Lower Sunshine Dam Enlargement, and McGee Gulch Dam were classified as secondary alternatives, 15 of the initially-considered 18 alternatives were evaluated in a two-staged screening process. Per direction from Mr. Michael Purcell, Director of the WWDC, the two key screening criteria were established as: 1) the ability of a project to meet the sponsor's purpose and need and 2) project cost considerations. These criteria were consistent with COE recommendations for initial screening of water resources projects [Purcell, 1994].

The screening process used to compare alternatives is illustrated on Figure 4.1. The first stage, called coarse screening, evaluated the ability of an alternative to meet the sponsor's purpose and need. Two essential aspects of the GVID's purpose and need are to provide sufficient supplemental irrigation water and river re-regulation benefits to significantly reduce periodic crop failures. Previous studies have indicated that supplemental water supplies of approximately 26,500 acre-feet on an average annual basis will substantially reduce crop failures [GEl, 1994-2]. This is consistent with the yield associated with Lower Roach Gulch Reservoir and reflects the amount of supplemental water that is currently needed and can be sold by the GVID [GEI,1994-2]. It is also essential that lower basin storage be provided in order to reduce water waste and provide for more efficient operation of the GVID system. Hence, the coarse screening criteria used in our comparative analysis were to provide a minimum of 26,500 acre-feet of average annual yield which can be delivered from a lower basin site. Projects that could not meet this yield and site location threshold were considered unable to meet the sponsor's purpose and need and were reclassified as secondary alternatives during coarse screening.

Those projects which met the first stage of coarse screening were then evaluated in terms the second screening stage which is called fine screening. Project investment was the sole criteria for fine screening. Previous economic evaluations and a survey of GVID members have indicated that there is a high interest among GVID shareholders to purchase supplemental irrigation supplies at an annual price of less than approximately $21 per acre­ foot [GEl, 1994-2]. The ability to sell shares at prices higher than this threshold drops dramatically as the price increases above this threshold. Hence, if the number of available shares in the project could not be made available for less than $21 per acre-foot, the alternative was reclassified as a secondary alternative.

94071\REPOR1YfEXT. VI 4-1 ALTERNATIVES CONSIDERED FOR COARSE SCREENING

1) TRANSBASIN DIVERSION (SHOSHONE EXT.) 8) ... AINSTE... DA... B

2) UPPER SUNSHINE RESERVOIR ENLARGE ... ENT 9) ... AINSTE... DA... C

3) LOWER ROACH GULCH DA ... 10) ...AINSTE... DA... 0

.) BLACKSTONE GULCH DA ... 11 ) ...AINSTE... DA... E

5) RAWHIDE CREEK DA ... 12) ...AINSTE... DA... F'

6) SPRING CREEK DAM 13) CONSERVATION

7) MAINSTE... DAM A 1.) GROUNDWATER

15) NO ACTION

COARSE SCREENING SCREENING CRITERIA: (PURPOSE AND NEED) AVERAGE ANNUAL YIELD AND RIVER RE-REGULATING LOCATION , 1

ALTERNATIVES CONSIDERED FOR FINE SCREENING

1) LOWER ROACH GULCH DAM

2) BLACKSTONE GULCH DA ...

3) MAINSTEM DAM A

.) NO ACTION

FINE SCREENING SCREENING CRITERIA: (PROJECT INVESTMENT) ANNUAL COST PER SHARE , 1

PRIMARY ALTERNATIVES FOR EIS SCOPING

1) LOWER ROACH GULCH DAM

2) BLACKSTONE GULCH DAM

3) NO ACTION

...... ~ ~ ~ ~~------,------~------f ~ WWDC / GVID <:> CHEYENNE, WYOMING GREYBULL VALLEY PROJECT INITIAL SCREENING !~------~ LEVEL II - PHASE VI PROCESS SCHEMA TIC ~ ~ GEl Consultants. Inc. PROJECT NO. 94071 MAY 1994 I FIGURE 4.1 With the exception of the No Action alternative, reconnaissance level estimates of total project investment and yield were extrapolated from previously developed information. These estimates along with the location of the project in the basin were used as the basis for coarse and fine screening. Project investment and yield information is summarized in Table 4.1 and additional information is provided in Appendices C and D, respectively.

TABLE 4.1 SUMMARY OF INITIAL SCREENING CRITERIA

Transbasin Diversion Shoshone Extension 91.8 30,000 -26,500 68.9 37.6 Existing Dam Enlargement Upper Sunshine Dam Enlargement 45.9 30,000 -26,500 34.4 19.33 Off-Channel Dam Sites Blackstone Dam 47.6 30,000 26,500 35.7 20.47 Rawhide Dam 40.2 30,000 30,000 30.1 17.60 Spring Creek Dam 61.1 30,000 29,100 45.9 25.73 Lower Roach Gulch Dam 43.2 30,000 26,500 32.4 18.73 Mainstem Dam Sites Dam Site A(2) 90.1 30,000 30,000 67.6 36.97 Dam Site B(2) 67.2 30,000 30,000 50.4 28.07 Dam Site C(2) 70.1 30,000 30,000 52.6 29.20 Dam Site 0(2) 80.0 30,000 30,000 60.1 33.07 Dam Site E(2) 98.2 30,000 30,000 73.7 40.10 Dam Site F 85.5 30,000 -15,000 64.1 35.17 Conservation Ditch Lining 27.8 11,500 11,500 20.9 30.69(5) Groundwater Wells 60.3 11,200 11,200 45.2 66.15(6) No Action N/A a a N/A N/A

Notes: 1) NtA = Not Applicable 2) The maximum yield was assumed to be limited to 30,000 acre-feet by reservoir storage capacity. 3) All costs are shown in 1995 dollars and have been escalated at four percent per year. 4) Costs per share include annual operation and maintenance costs and assumes 30,000 or maximum available shares sold. 5) Assumes 11,500 shares sold. 6) Assumes 11,200 shares sold.

As illustrated on Figure 4.1, only four of the 15 alternatives considered met the yield and project location criteria associated with the coarse screening. As a result of this first stage

94071 \REPOR1\TEXT. VI 4-2 of screening, the conservation alternative was reclassified as a secondary alternative because it provided only 11,500 acre-feet of supplemental water. The transbasin diversion project, Upper Sunshine Reservoir Enlargement, Rawhide Creek Dam, Spring Creek Dam and Mainstem Dam Sites B through E all provide adequate yields, but are not sited in a location to improve river re-regulation benefits. This is very important to allow for more efficient operation of the GVID system. Mainstem Dam Site A remained as a primary alternative after coarse screening because of its lower basin location. The groundwater alternative was developed to provide an additional water supply of approximately 11,000 acre-feet and it was assumed that it would be possible to construct additional wells and pipelines at comparable acre-foot unit costs to meet the average annual yield criteria of 26,500 acre-feet. However, it does not provide river re-regulation benefits. The No Action alternative did not meet the coarse screening criteria, but remained as a primary alternative consistent with the requirements of NEPA.

The remaining four alternatives which met the coarse screening criteria were then evaluated in fine screening with respect to the cost criteria. Mainstem Dam Site A was subsequently reclassified as a secondary alternative due to high costs. Therefore, the alternatives which met both the coarse and fine screeni~g criteria are listed as follows:

• Lower Roach Gulch Dam • Blackstone Dam • No Action (required by NEPA)

It is again important to note that additional primary alternatives can be included in the EIS through the scoping process. Additional studies may also result in the reclassification of some secondary alternatives as primary alternatives, or may result in the development of alternative systems consisting of components of several individual projects.

The initial screening process was performed based on our experience with other similar water resources projects, but lacks one of the key aspects of success that will be required during the EIS. The key element is that the screening and permitting decision analysis be conducted in an open and public forum where all project stakeholders have the opportunity to provide input and review the trade-offs associated with competing resource objectives.

94071\REPORT\TEXT.VI 4-3 This section includes a proposed method for ranking EIS alternatives and includes an example of this method. Other EIS planning considerations are also provided for additional information.

5.1 PROPOSED METHODOLOGY FOR COMPARING AND RANKING EIS ALTERNATIVES

The evaluation of alternatives in the EIS process requires a decision framework that can objectively compare the alternatives through a systematic evaluation of a large array of attributes. Decision support systems (DSS) are a well recognized means of accomplishing this task. While it may be recognized by several names, a DSS essentially consists of a participatory polling (group-based decision) process developed by the Rand Corporation after World War II for use in making strategic military decisions [Kappus, 1994]. Over the past 20 years, the process has been refined to apply to decisions concerning siting studies, such as the current effort by the aVID and WWDC.

The development of a DSS requires several steps. First is the development of a "Hierarchy of Planning Values". The hierarchy takes the form of a decision tree and consists of several levels of values such as goals, subgoals, objectives and finally criteria. Planning values represent issues that are judged to be important to the decision making process for a particular project. The usefulness of the hierarchy derives from the observation that goals can be set and analyzed in such a manner that the essential factors contributing to their achievement can be identified and defined. If necessary, these contributing factors can be expressed in terms of intermediate goals that can be similarly analyzed. The process of subdividing intermediate goals into their component elements continues until a set of fundamental decision criteria is identified. This process provides a complete set of criteria that are consistent with, and are derived from overall project policies and goals, the scope of the project, and the characteristics of the environment in which the project is located.

Structuring the hierarchy of project values is largely judgmental. It requires an orderly, interactive examination of numerous project-related factors by an interdisciplinary group of individuals who are knowledgeable about the goals and purposes of the project being studied, as well as the local setting. The output of this effort is a set of pertinent project objectives and explicit criteria that represent the key decision factors that will be used to evaluate the various alternative solutions to meet the project goals and objectives.

Once the hierarchy is developed, preference relationships (utility functions) are developed for each of its criteria. The development of preference relationships requires several steps, the first of which is the identification of the "measures" of the criteria in terms of some definable unit such as dollars, acres, linear feet, etc. Next a common preference rating scale

94071\REPOR1\TEXT.VI 5-1 is developed that will be applied to all criteria. Once these two items are identified, the preference relationship is established by developing the relationship between the measure (generally shown on the "x" scale of a two-dimensional plot), and the common preference rating scale (generally shown on the "y" scale). The preference relationship can be a linear, bi-linear, step, hyperbolic, or other appropriate function.

The final step is the development of weighting factors for each functional level within the hierarchy. The weighting factors are assigned in the range of 0 to 1.0. To provide the necessary mathematical integrity within the model, the sum of the weights assigned to each variable emanating from a node within the decision tree must equal 1.0. For example, the sum of the weighting factors for all goals must equal 1.0. Likewise, the sum of the weighting factors for each subgoal under a particular goal must also equal 1.0. A composite weight indicating the relative importance of each measurable criteria can be developed by the following equation:

CCW = GW x SW x OW x CW

where GW, SW, OW, and CW represent the weighting factors for the related goal, subgoal, objective and criteria.

Preparation of a functional hierarchy including the definition of criteria and their corresponding measurement systems represents a management framework that should guide the data gathering requirements for preparation of the EIS. Hence, the development of the DSS including the hierarchy should be developed as early as possible during the EIS process in order to prevent unnecessary and inefficient data gathering efforts.

Based on our experience with other water resource projects and our understanding of the general institutional and environmental setting of the Greybull River basin, we have prepared a preliminary hierarchy for guiding future EIS work for the project. This functional hierarchy is shown on Figure 5.1. This hierarchy includes four overall project goals including:

1. Minimize Environmental Impacts 2. Minimize SociallEconomic Impacts 3. Maximize Sponsors Operational Effectiveness 4. Minimize Overall Project Costs

The four functional levels within the model result in nineteen functionally independent criteria. We recommend the EIS scoping process be initiated with this hierarchy. It should be appropriately modified based on input from the scoping process, including comments from Federal and State jurisdictional agencies.

9407l\REPOR1\TEXT. VI 5-2 MEASURED PREFERENCE GOALS SUBGOALS OBJECTIVES CRITERIA RELA nONSHIP (SCORES} f RSHERIES ~1; WE1l.ANDS MINIMIZE IMPACTS TO BIOLOGICAL HABITAT ~ SENSlTI'JE HABITAT MINIMIZE BIOLOGICAL . I I MINIMIZE IMPACTS TO SENSITIVE SPEaES .... SENSlTI'JE SPECIES RESOURCE IMPACTS 0 ) I MINIMIZE HABITAT FRAGMENTATION 5. lARGE MAMMALS MINIMIZE ENV'lRONMENTAL 0 IMPACTS I I MINIMIZE IMPACTS TO HISTORICAL RESOURCES I I C HISTORICAL RESOURCES MINIMIZE CULTURAL 0 RESOURCE IMPACTS D MINIMIZE IMPACTS TO PREHISTORICAL RESOURCES 1.: PREHISTORICAL RESOURCES 0 CJ

FEDERAL LANDS MINIMIZE LAND I I MINIMIZE LAND USE IMPACTS a. USE IMPACTS 0<8 L PRIME AGRICUlTURAL LANDS

MINIMIZE SOCIAL 10- CONSlRUCTION TRAFFlC GREYBULL IMPACTS MINIMIZE TRAFFIC IMPACTS VALLEY 11. ROAD RELOCATION PROJECT MINIMIZE COMMUNITY IMPACTS ECONOMIC GAIN MAXIMIZE LOCAL ECONOMIC BENEFITS RECREATIONAL USER DAYS

c::J MINIMIZE WATER QUAlITY IMPACTS rd 14. WATER QUAlITY 0

0 D .15; SYSTEM YIELD * MAXIMIZE SPONSORS MAXIMIZE OPERATIONAL MINIMIZE IRRIGATION SHORTAGES 1•• ANNUAL IRRIGATION SHORTAGES OPERA TlONAL EFFECTIVENESS REUABIUTY AND EFFICIENCY .... IMPROVE EXISTING OPERATIONS t7. RIVER RE-REGUlATlON ! 0 CJ *

MINIMIZE WWDC INVESTMENT MINIMIZE W'K>C F1JNDlNG TOTAL PRO.£CT COSTS .... * I MINIMIZE O'JERALL PRo.£CT COSTS ~ MINIMIZE GV'lD INVESTMENT MINIMIZE GVlD SHAREHOLDER COST ,. !CO I I r ANNUAL COST PER SHAREHOLDER (;{ 0 ACRE-FOOT * ~ ~ ~ ! ! LEGEND ~ 0 - =Ttr~~~A~:rOlNT • - ~RI;~~:L MsEtiEuE~~~G WWDC / GVID PRELIMINARY PLANNING ~ COMPUTED MODEL CHEYENNE. WYO ... ING GREYBULL VAu.£Y PROJECT FUNCTIONAL HEIRARCHY f c:J - INDICATES LOCATION WHERE LEVEL II - PHASE VI FOR THE r WEIGHT IS REQUIRED FOR (I)..... GREYBULL VALLEY PROJECT MODEL COMPUTATION . .. ------.....--+-----~r_-----_t ~L______~.== .. ~. ~G=E~I~C~o~n~s~u~lt=a~n~t~s~.~ln~c~.~L_· ___P_RO_J_E_C_T __ NO_. __ 9_40_7_1 ____ ~_ ... _A_Y __ 1_9_94 __ ~F_IG_U_R_E ___ ._5_.1~ 5.2 EXAMPLE APPLICATION OF SIMPLIFIED SCREENING MODEL

To illustrate how a DSS can be applied to this project, we have performed an example evaluation using the screening criteria described in Section 4. This includes system yield, river re-regulation benefits (project location) and total project cost. These correspond to criteria 15, 17, 18, and 19 shown on Figure 5.1.

An example of a simplified hierarchy of planning values using only four criteria is shown on Figure 5.2. Example weighting factors are also presented in this figure. For those examples we have weighted the three overall project goals of minimizing project investment, maximizing sponsor's operational effectiveness and maximizing available water used at 0.5, 0.25 and 0.25, respectively. It is important to note that the sum of these weights equals 1.0. In addition, the sum of the weights associated with the subgoals of minimizing WWDC cost and GVID cost also equal 1.0. For this example we have weighted these subgoals as a direct inverse of the 75 percentl25 percent WWDC financing. Once the basic scoring model has been developed, it can be easily manipulated to perform sensitivity analysis and illustrate the trade-offs associated with competing goals, subgoals, and objectives. Example preference relationships which may be applicable to the Greybull Valley Project are illustrated on Figure 5.3.

A summary of example results for the 15 alternatives considered in our comparative evaluation is shown graphically on Figure 5.4. The score for each criteria is indicated separately by the different hatching patterns on this figure. As can be seen, the two viable recommended primary alternatives for consideration in the EIS received the highest scores in this example. The No Action alternative did not rank in the top five of those alternatives evaluated, but must be included as a primary alternative in the EIS as specified by the Council on Environmental Quality regulations (CEQ, 40 CFR 1500-1508).

5.3 OTHER ISSUES AND PLANNING CONSIDERATIONS

Some very significant additional issues associated with other goals, subgoals, and objectives were not addressed in our initial screening. These issues can be expected to develop during the EIS process. A general issue that can be expected to be raised is that the level of the evaluations associated with all alternatives, except Lower Roach Gulch, is preliminary. Key technical issues associated with yield analysis, geotechnical concerns, and constructability need to be evaluated in greater detail for each alternative. The results of these analyses may increase or decrease the reconnaissance level estimates of project investment or yields and impact the project's overall ability to meet the GVID's purpose and need. A discussion of some of these key issues follows.

5.3.1 Primary Alternatives

Data extrapolations from previous modeling performed by SWWRC indicate that there could be 40,000 to 80,000 acre-feet of additional water available in the Upper Greybull River and

94071\REPOR1\TEXT.YI 5-3 MEASURED PREFERENCE RELA TIONSHIP GOALS SUBGOALS CRITERIA (SCORES)

TOTAL PROJECT COST See Fig 5.3A

MINIMIZE PROJECT INVESTMENT

ANNUAL SHAREHOLDER See COST Fig 5.38 GREYBULL VALLEY ~ PROJECT ~ ! Q MAXIMIZE AVAILABLE MAXIMIZE SYSTEM YIELD PROJECT YIELD See ..... c WATER USE Fig S.3C a:~

~ I ~ S. 13Vi ~ ~ MAXIMIZE SPONSORS MAXIMIZE OPERATIONAL RIVER RE-REGULATION See ~ OPERATIONAL RELIABILITY AND EffiCIENCY Fig 5.30 ~ EffECTIVENESS ...... ~ LEGEND ~ ~ o - INDICATES NODAL POINT G WHERE SCORES ARE E COMPUTED WWDC / GVID EXAMPLE ~ [==:J - INDICATES LOCATION WHERE GREYBULL VALLEY PROJECT c:> WEIGHT IS REOUIRED FOR CHEYENNE, WYOMING INITIAL SCREENING MODEL ! MODEL COMPUTATION LEVEL II - PHASE VI FUNCTIONAL HEIRARCHY ~ ~ GEl Consultants, Inc. PROJECT NO. 94071 MAY 1994 FIGURE 5.2 ~------~------~~~------~------100 100

90 90

80 80

70 70

60 60 w W a:: 0:: 8 50 8 50 II) VI

30 30

20 20

10 10

10 20 30 40 so 60 10,000 20,000 30,000 WWDC COST, ~ILLION $ YIELD, AF A. TOTAL PROJECT COST C. PROJECT YIELD 100------100

90 PROJECT LOCATION eo PROVIDES RIVER RE -REGULATION o 70 ~ C 60 ~ W w 0:: a:: It 8 so 8 so "') VI II) I ~ S. 30 ~Vi PROJECT LOCATION 20 DOES NOT PROVIDE ~ RIVER RE-REGULATION ~ ~ 10 ~ O+------.--~--~----~--~--~ o g 0 10 15 20 30 40 ~ GVID COST, $/AF D. RIVER RE-REGULA TION B. ANNUAL SHAREHOLDER COST ~ E ~ WWDC / GVID EXAMPLE GREYBULL VALLEY PROJECT o CHEYENNE, WYOMING INITIAL SCREENING MODEL LEVEL II - PHASE VI ! PREFERENCE RELATIONSHIPS § ~ GEl Consultants, Inc. PROJECT NO. 94071 MAY 1994 FIGURE 5.3 ~------~~------~------~------~ 90.0 • River Re-regulation 80.0 1m Project Yield 70.0 o GVID Cost

60.0 II WWDC Cost

50.0

40.0

30.0

20.0

10.0

0.0 (]) c w c u...... c ..c ...:: « c .... CD u 0 (]) (J (J c o 0 (]) "iii (]) +-' u (]) U (]) (]) (]) ".;:; co :::J ..c ".;:; +-' +-' +-' +-' co +-' co (]) +-' (J C) co O..c C) en ..c ~ (J "'C C en en en en a: c en « en en > "'C .... :::J (]) ..c :::J "§. Q; c c (])C) c CJ) o en co :::J ~ z CJ) ~ 0 co .... c .:: +-' (]) 0 e 0 en a: C) ...J ..::.t. Q. u (J Q. co :::> OJ

WWDC / GVID GREYBULL VALLEY PROJECT EXAMPLE RESULTS CHEYENNE, WYOMING OF INITIAL LEVEL II - PHASE VI SCREENING MODEL

<::Jr) GEl Consultants, Inc. PROJECT NO. 94071 MAY 1994 FIGURE 5.4 Wood River. However, most of this water is available as excess run-off only during June and July. We have assumed that, on average, an additional 225 cfs could be diverted from the Upper Greybull River to provide water to an enlarged Upper Sunshine Reservoir, Rawhide Creek Reservoir, or Spring Creek Reservoir. If a closer evaluation of diurnal river fluctuations in this area indicates that this is not possible, these three projects would not meet the yield criteria associated with our coarse screening described in Section 4. These projects do not provide the river re-regulating benefits of our coarse screening criteria.

The most significant cost item associated with the Blackstone Dam Project is the diversion tunnel in the left abutment. A more detailed assessment of technical feasibility for this concept could significantly increase or decrease the costs associated with this primary alternative. A conservative cost estimate has been provided to date. If lower unit costs for tunneling can be provided by more detailed investigations, significant cost savings could be realized over the Lower Roach Gulch Project.

5.3.2 Secondary Alternatives

Enlargement of Upper Sunshine Dam. would require that outlet tunnels be constructed in the foundation or abutments of both Upper and Lower Sunshine Dams. A geotechnical assessment of the overall feasibility of this concept would be critical to any further serious considerations. In addition, this alternative would require that each reservoir be drained for at least one irrigation season to construct these features. The environmental and economic impacts associated with draining these reservoirs are expected to be significant and were not included in our initial screening.

An important item that was not included in our cost estimate must be considered when evaluating the Shoshone River Transbasin diversion. There is a provision in the WWDC contract with the USBR that allows the WWDC to defer payment for the next 10 years on the soon-to-be- completed Buffalo Bill Reservoir enlargement. Deferred payment may only take place if the State does not use the yield from the project during that 10-year period. The penalty for use of the yield before that time would be approximately $2 million which would add significant cost to the already expensive Shoshone River Transbasin alternative.

The key element that most conservation projects cannot provide is timely irrigation deliveries. High value crops such as sugar beets and dry beans must have a constant, reliable supply of water to survive. This can best be provided by storing excess river flows for supplemental use when the flow is not available in the river. The impact of timely water deliveries was not included as part of our initial screening criteria and could be significant for any future conservation project. In addition, lower basin storage should be considered as a very important aspect of water conservation because it provides the ability to capture and reuse existing river flows which are currently wasted during spring run-off and during the winter return flow months.

Two key challenges are associated with the groundwater development alternative. These include reduced return flows associated with the interconnection of groundwater in the

94071\REPOR1\TEXT. VI 5-4 alluvial deposits with the Greybull River and extensive pumping that would eventually interfere with groundwater supplies of existing wells in the area. Both of these conditions could result in regulation of wells by the Wyoming State Engineer which could further reduce the overall feasibility of this alternative.

94071\REPORT\TEXT.VI 5-5 A preliminary purpose and need statement for the Greybull Valley Project has been developed. A review of previous studies and discussions with the GVID and the WWDC has resulted in the identification of 18 independent project alternatives that could have the potential to meet the initial purpose and need of the GVID.

Three of the originally considered 18 alternatives were reclassified as secondary alternatives based on technical or practicability issues. Concepts and reconnaissance level yield, river re-regulation and investment screening criteria have been developed for the remaining 15 alternatives. These projects were subject to a two-staged comparative screening analysis which has resulted in our recommendation of two primary alternatives and the No Action scenario for consideration in the EIS scoping process.

In addition, we have developed a functional planning hierarchy including the definition of criteria and their corresponding measurement systems which can be represented in a management framework. The hierarchy could be used to guide the data gathering requirements for preparation of the EIS. The development of a decision support system including the planning hierarchy, if developed as early as possible during the EIS process, has the potential to prevent unnecessary and inefficient data gathering efforts and provide the sponsor with the ability to establish responsible management of the process.

6.1 PRIMARY ALTERNATIVES FOR EIS CONSIDERATION

We recommend that the GVID consider three primary alternatives in future EIS scoping documents and public meetings. These alternatives include:

• Lower Roach Gulch Dam • Blackstone Gulch Dam • No Action Scenario

As previously documented, storage is the key to more efficient use of the available water in the Greybull Basin and two of our three primary alternative recommendations are storage projects [HDR, 1988].

6.2 RECOMMENDATIONS FOR FUTURE EIS MANAGEMENT

We recommend that a decision support system model be considered as a tool to develop consensus and evaluate alternatives during the EIS. To be successful, the model must be developed in a very open public forum so that all interested project stakeholders understand the issues and trade-offs associated with permit decisions for the project. It is our

9407I\REPOR1'.TEXT.VI 6-1 recommendation that a diverse committee representing the interests of the sponsors, the WWDC, regulatory agencies, environmental groups, and citizens' groups be formed during the EIS scoping process to develop and refine the decision analysis model.

94071\REPOR1\TEXT.VI 6-2 1. Bereman, 1989, "Reconnaissance Report on Roach Gulch Reservoir Site, Park County, Wyoming," prepared for the Greybull Valley Irrigation District, July.

2. GEl Consultants, Inc., 1991-1, "Phase I Draft Summary Report - Greybull Valley Dam and Reservoir," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, GEl Project No. 90214, January.

3. GEl Consultants, Inc., 1991-1, "Appendices A through D to the Phase I Draft Summary Report - Greybull Valley Dam and Reservoir," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, GEl Project No. 90214, January.

4. GEl Consultants, Inc., 1991-2, "Phase II Summary Report - Greybull Valley Dam and Reservoir," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, GEl Project No. 91075, August.

5. GEl Consultants, Inc., 1991-2, "Enclosures 1 through 3 - Phase II Summary Report - Greybull Valley Dam and Reservoir," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, GEl Project No. 91075, August.

6. GEl Consultants, Inc., 1992, "Addendum No.2 to Appendix A - Geotechnical Investigations Report of Alternative Borrow Sources on Private Property Downstream of the Lower Dam Site - Greybull Valley Dam and Reservoir," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, GEl Project No. 91239, April.

7. GEl Consultants, Inc., 1992, "Level II, Phase III, Draft Conceptual Design Report, Greybull Valley Dam and Reservoir Project," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, August.

8. GEl Consultants, Inc., 1994-1, "Greybull Valley Dam and Reservoir Project, Final Level II, Phase IV Summary Report, Small Reclamation Projects Evaluation," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, August.

9. GEl Consultants, Inc., 1994-2, "Greybull Valley Dam and Reservoir Project, Level II, Phase V, Final Conceptual Design Report," prepared for the Wyoming Water Development Commission and the Greybull Valley Irrigation District, GEl Project No. 93151, August.

94071\REPOR1\TEXT.VI 7-1 10. HDR, 1988, "Guidebook for Water Resources Management & Development, Big Horn & Clarks Fork Basins - Final Report," prepared for the Wyoming Water Development Commission, October.

11. Kappus, Ulrich, et. aI., 1994, "San Diego County Water Authority's Emergency Storage Project, Supplying Water During Natural Disasters," presented at Water Policy and Management: Solving the Problems, Proceedings of the 21 st Annual ASCE Water Resources and Management Conference, Denver, Colorado, May.

12. Libra, Robert et aI, 1981, "Volume II-A, Occurrence and Characteristics of Ground Water in the Bighorn Basin, Wyoming," prepared for the U.S. Environmental Protection Agency, June.

13. Libra, Robert et aI, 1981, "Volume II-B, Occurrence and Characteristics of Ground Water in the Bighorn Basin, Wyoming," prepared for the U.S. Environmental Protection Agency, June.

14. Purcell, 1994, "Personal Communication from Michael Purcell, Director of the WWDC, April.

15. Soil Conservation Service, 1986, "Bench Canal Irrigation System Report, Wyoming Cooperative Irrigation Water Conservation Study," prepared in cooperation with the Wyoming State Engineer's Office, U.S. Department of Agriculture and Wyoming State Engineer's Office.

16. States West Water Resources Corporation (SWWRC), 1994, "Greybull Valley Dam, Level II, Phase VI - Alternatives Potential Groundwater Development Alternative," prepared for GEl Consultants, Inc., April.

17. U.S. Department of the Interior, 1959, "Status Report - Shoshone Extensions Unit (South) Wyoming, Missouri River Basin Project," prepared for the Yellowstone­ Bighorn Projects Office, Cody, Wyoming, January.

18. Watts, 1994, "Economic Costs of the No Action Alternative for the Greybull Valley Project," prepared for GEl Consultants, Inc., August.

94071\REPORnTEXT.VI 7-2 GROUNDWATER EVALUATIONS Suite 204, Pioneer Center 2424 Pioneer Avenue P.O. Box 2092 Cheyenne, Wyoming 82001 Cheyenne, Wyoming 82003 (307) 634-7848 FAX: (307) 634-7851

----=-=~ --~.~~~ . rr-D ... :. ':"" t.. .. - .~~.- April 11, 1994 \ APR 1 4 94

• -.' ..... ?" -"lT~, Inc. Mr. Steve Jamieson ·~·i). ~2G2 ) ~';111 GEl Consultants \ 5660 Greenwood Plaza Blvd. Suite 202 Englewood, CO 80111

Re: Greybull Yalley Dam Level n - Phase VI - Alternatives Potential Groundwater Development Alternative

Dear Steve:

Enclosed is the attached report outlining the potential for groundwater development as an Alternative to the Proposed Action for the Greybull Valley Dam and Reservoir Project. Please review the document and call with any questions which you may have.

The authors of this document from SWWRC are Marlin Lowry and David McElhaney.

Sincerely, ~ Michael T. O'Grady, Vice President FILE COpy Proj.lProp." 91{D7! Folder ...ci.. ·... l) ______cc: Karen Mumper, SWWRC Marlin Lowry, SWWRC fGIder Tdte 7iual -2- &lmAIJ9 lJJ a~ Vic Anderson, SWWRC David McElhaney, SWWRC GREYBULL RESERVOIR ALTERNATIVES

Groundwater Alternative

Introduction

Irrigation of croplands in the Greybull River Valley (Figure 1) has been accomplished for more than 100 years primarily by diversions of water from the Greybull River. A small amount of groundwater has provided an additional supply for irrigation of a limited number of acres in the valley since about 1930 (state Engineer records).

A preliminary analysis of the potential to supply additional water for irrigation from groundwater was conducted from available published information and public records. A bibliography of relevant publications is attached. Analyses were conducted to evaluate potential groundwater deliveries at times of surface water deficiencies (April, August and September) and at rates comparable to predicted supplies from the proposed Roach Gulch reservoir (approximately 11,200 acre-feet).

Geology/Geohydrology

The Greybull River Valley lies in the Bighorn Basin of north­ central Wyoming. The Bighorn Basin is an asymmetric syncline bounded by compressional uplifts formed during Laramide orogenic activity in late Cretaceous and early Tertiary time. The struc­ tural axis of the basin is oriented in a generally northwest to southeast direction near the west basin margin.

Basin margins are defined to the north and east by the Pryor Mountains in Montana and Bighorn Mountains of Wyoming. The Owl Creek Mountains form the southern boundary of the basin. The west basin margin is formed by the Beartooth Uplift and Laramide structures overlapped by Yellowstone and Absaroka volcanics.

1 10a030' MONTANA 15' 100°00' _...... -- 45°00' r -- Wyl(jMING -,-...... ---.- ~Fr.nni8 I ~"_""n"

o 5 10 15 20MILES 1--.-,--I'~ir--ij-_..---l J o 5 10 15 20 KILOMETEnS

FIGURE 1. Location Map of Study Area Typical of Laramide style deformation, basement rocks of Precam­ brian age form the core of the uplifts and are exposed at the surface in the uplifted structures. Rocks deposited during Paleozoic and Mesozoic eras flank the uplifts and the central basin area is covered by Tertiary and Quaternary sediments.

Previous groundwater investigations in the Bighorn Basin indicate the Paleozoic and Quaternary aquifer systems have potential for groundwater development for irrigation use (Appendix, Table 1). The thick sequence of rocks lying stratigraphically between the Paleozoic aquifer system and Quaternary sedimentary fill contains minor aquifers that generally yield only small quantities of water and/or contain water of poor quality.

Paleozoic Aquifer System

Paleozoic aquifers include the sequence of marine sediments from the top of the Tensleep Sandstone through the Flathead Sandstone. outcrops of the Paleozoic sequence nearest the study area are mapped south and west of Cody, Wyo. and. north of the Town of Greybull (Figure 2). Distances to these outcrops from the diver­ sion structure on the Greybull River for the Farmers and Bench canals are approximately 28 miles and 25 miles, respectively. Rocks of Paleozoic age near the west basin margin dip steeply into the basin so that depths to the sequence become too great for economical drilling in a short distance from the outcrop. Extensive structural deformation along the western basin margin may have also disrupted the continuity of the aquifer sequence in that area, thereby restricting recharge to the aquifer at depth. The top of the Paleozoic sequence in the study area lies at depths of about 15,000 feet to 18,000 feet below the land surface (Figure 3). Potential for development of groundwater for irriga­ tion supplies from Paleozoic aquifers is therefore, confined to the eastern basin margin where drilling depths are reasonable.

3 GEOLOGIC MAP OF BIGHORN BASIN

2

Wells constructed in the Paleozoic aquifer system in the Bighorn structural basin commonly yield from 25 gallons per minute (gpm) to 200 gpm (Libra et aI, 1981). Plafcan et al (1993) reported a median yield of 508 gpm from 16 wells completed in the Madison­ Bighorn portion of the Paleozoic aquifer system. yields in the basin have been reported from 2 gpm to 14,000 gpm.

Specific capacities for wells constructed into the Paleozoic sequence range from 0.20 to 10.2 gpm per foot of drawdown (Libra et aI, 1981). Specific capacities of less than 1.0 gpm per foot of drawdown are calculated for most wells completed in the Paleo­ zoic aquifer system in the basin. Transmissivity values range from 0.9 to 1900 square feet per day (Plafcan et aI, 1993).

Most wells are artesian and many flow at the land surface. Average artesian heads (converted from wellhead shut-in pres­ sures) are reported to have declined more than 150 feet between 1968 and 1988 in six wells completed in the Madison-Bighorn sequence (Plafcan et aI, 1993).

Recharge of the Paleozoic sequence occurs chiefly by infiltration of precipitation in the outcrop area. Water from wells located near the recharge area commonly contains less than 500 milligrams per liter (mg/l) of total dissolved solids (TDS). TDS tend to increase in the aquifers to more than 3000 mg/l at greater dis­ tances from the outcrop and aquifer depth.

Potential Alternative water Source

We believe that further evaluation of the Paleozoic aquifer system as an alternative source of irrigation water for the Greybull Valley Irrigation District (GVID) is probably not worth­ while. Two major factors lead to this conclusion:

6 1. Estimated cost of a water delivery system.

Distance of water conveyance from the groundwater source to the area of irrigation use is the primary cost factor. The nearest outcrops of the Paleozoic sequence are located in T.53 and 54 N., R.93 and 94 w. and are about 25 miles northeast of the diversion structure for the Farmers and Bench canals on the Greybull River. However, the Paleozoic units at that location have a limited outcrop area for recharge and appear to produce small yields of relatively poor quality water.

The nearest potential sites for the construction of water wells into the Paleozoic aquifer system lie approximately 33 miles east of the diversion in T.51 and 52 N., R.91 and 92 W. Estimated costs for well drilling and pipeline construction to convey 11,200 acre-feet of water in a 90 day period are:

Drilling (28 wells, see Table 2) ... $ 5,000,000 Collection pipelines (24-inch) ..... $ 7,000,000 Delivery pipeline (36-inch) .....•.. $25,000,000

Total ...... $37,000,000

Cost estimates do not include pump and power costs and test well expenses.

2. Areal variability of hydrologic characteristics in the Paleozoic aquifer system reduces the chance of successful well completion with adequate well yield.

Yields in excess of 1000 gpm are not uncommon from wells completed in the Paleozoic sequence, but most well yields are significantly less. Table 2 indicates that 28 wells capable of sustaining a yield of 1000 gpm each are needed to deliver 11,200 acre-feet of water in 90 days. Construction of this many wells

7 TABLE 2

GREYBULL RESERVOIR ALTERNATIVES GROUND WATER ALTERNATIVE PALEOZOIC AQUIFERS Number of wells needed to supply 11,200 acre-feet Yield per well = 1000 gpm For T.D = 2000 ft For T.D.= 3000 ft Acre-Feet Total Number Estimated Cost Estimated Cost Jays Per Day GPM of Wells Drilling/Casing Drilling/Casing

30 373.3 84495 84 $12,222,000 $18,270,000 60 186.7 42259 42 $ 6,111,000 $ 9,135,000 90 124.4 28158 28 $ 4,060,000 $ 6,090,000 120 93.3 21118 21 $ 3,045,000 $ 4,567,500 150 74.7 16908 17 $ 2,465,000 $ 3,697,500 180 62.2 14079 14 $ 2,030,000 $ 3,045,000

Cost estimates include: Surface casing to 150 ft (cemented) 10 1/4-inch hole with 8 5/8 steel casing (cemented Rig-up charge and blow-out protection

8 that yield 1000 gpm or more requires many wells to be located at sUbstantial distances from a central water collection point when well spacing and existing water rights from the aquifers are considered.

Well spacing, potential yields ang number of wells needed for the desired quantities of water for this project can not be precisely determined from available hydrologic information in the area. In general, to diminish the effects of interference between wells, they should probably not be spaced less than about 0.5 mile apart. Several test wells would have to be constructed to determine aquifer properties and potential for development of sufficient well yields. Adequate well spacing could then be determined.

The top of the Paleozoic aquifer system in the Burlington and otto, Wyo. area is estimated to lie at elevations between -11,000 feet and -14,000 feet (mean sea level datum) or 15,000 feet to 18,000 feet below the land surface. Depths to the Paleozoic sequence decrease eastward to an estimated 6000 feet to 7000 feet below the land surface near the Town of Greybull. Aquifer depths at these locations and the distance from the recharge area reduce the chance of producing water of suitable quality for irrigation. The Paleozoic sequence is also buried too deep to economically construct water wells in the area.

Quaternary Aquifers

The Greybull Terrace and flood-plain alluvium between Burlington and otto, Wyoming offer the best potential for development of ground water for irrigation (Cooley"et aI, 1979). Combined, these deposits have a thickness up to 60 feet, but are less than 35 to 40 feet thick throughout most of the area. Groundwater recharge to the terrace and flood-plain deposits in the study area is primarily a result of infiltration of irrigation water and, to a lesser extent, from precipitation (Robinove et aI,

9 1963). The water table in the aquifer rises in the spring with the application of irrigation water on the surface of the alluvial deposits and declines when irrigation ceases (Robinove et al,1963). Ground water levels continue to decline until recharge from irrigation resumes the following season. Groundwater fluctuations in the study area of nearly 20 feet are reported (Robinove et aI, 1963). Groundwater elevation in the alluvium is controlled by the stage of water in the Greybull River (Cooley et aI, 1979).

Greybull Terrace Deposits

The deposits of the Greybull Terrace consist of pebble to cobble­ size material overlain in part by one to three feet of silt and silty sand (Cooley et aI, 1979). The terrace deposits are from 30 feet to 50 feet thick in the study area. The extent that Greybull Terrace deposits are exposed near the Greybull River is shown on Plate 1. saturated thickness of the terrace deposits ranges from 20 feet to 45 feet (Robinove et aI, 1963) depending primarily on the amount and duration of irrigation on the terrace surface.

Wells completed in the deposits mapped as the Greybull Terrace are capable of yielding 900 gpm or more (state Engineer's Office - personal communication) and have estimated specific capacities near 60 gpm per foot of drawdown. Water quality in the Greybull Terrace deposits is generally good with TDS ranging between 385 mg/l and 887 mg/l (Cooley et aI, 1979).

Flood-Plain Alluvium

The flood-plain alluvium of the Greybull River consists of unconsolidated clay to boulder-size material deposited during flooding of low areas adjacent to the river. Flood-plain alluvium is up to 30 feet thick in the study area and groundwater levels are often found within 3 to 10 feet of the land surface.

10 The water table fluctuates with the amount of irrigation water applied in the area and changes in stage in the Greybull River.

Wells completed in the flood-plain alluvium yield from 5 gpm to 140 gpm with specific capacities of 1 to 200 gpm per foot of drawdown (Plafcan et aI, 1993). Water quality in the flood-plain deposits is similar to water quality in the Greybull Terrace deposits. TDS tend to increase in a downstream direction to more than 2000 mg/l east of otto (Cooley et aI, 1979).

Potential Alternative water Source

Groundwater appears to be available for some development from the alluvial aquifer in the area, but two primary conditions will limit the amount of water that can be developed.

1. Limited saturated thickness and areal extent of the aquifer.

Cooley (1979) stated "the thickness forms a major control on the amount of water that can be obtained from the alluvial deposits" (Cooley et aI, 1979).

Existing irrigation wells may yield 900 gpm or more from the unconsolidated material in the area indicated to have the best potential for groundwater development (Figure 4.), but the limit­ ed saturated thickness of the aquifer suggests that such yields may only be attainable for short pumping durations even if the deposits possess optimum aquifer properties. Wells capable of sustained yields of 1000 gpm would probably have to be construct­ ed with deeply buried horizontal drains to intercept additional groundwater.

Water quantities required for early spring irrigation do not appear to be available from the alluvial aquifer due to the diminished saturated thickness of the deposits at that time. Groundwater elevations are at their lowest in April, just prior

11 n. 96 W. R. 95 w.

.1 - -j F' V f::!. ] . C.-)f) t· mf.~ n t - r'()u 110 tAl ater- F i (Jt.t rF:! 4. (~f'E'a "tOf' (... (1;;;hadE:-d). of ~~. Coo 1 ey in Va:l. J !-';.'y' ...., F,"'om. a. nd to commencement of irrigation from surface water diversions. Depth to water in alluvial deposits may be as much as 25 to 30 feet below the land surface in April (Robinove et aI, Tbl. 4, 1963) because of natural discharge to the Greybull River through late winter and early spring. Groundwater pumpage during the late irrigation season would diminish the amount of aquifer storage available for discharge to the river and may further lower early spring groundwater levels.

2. Potential interference with existing water wells and adverse effects on flow in the Greybull River.

It appears that good hydraulic communication exists between the alluvial aquifers and surface water sources in the study area. Some dewatering may be beneficial by lowering the water table in areas where it is at or near the land surface and water is being lost to evaporation, but pumpage of amounts greater than what is normally lost to evaporation would reduce the amount of irrigation return flow discharged back into the river system. Wells located close to the river could have a more direct effect on stream flows. Groundwater modeling may provide some indication of the cumulative effects of well pumpage on stream flows.

Plate 1 indicates the approximate location of existing water wells permitted by the state Engineer in the area and their reported depths, static water levels and yields. Siting of 28 or more new wells in the relatively small area without adverse effects on existing groundwater rights may be difficult. Groundwater pumpage that produces adverse effects on stream flow and/or existing groundwater rights may induce regulation of the well field by the State Engineer.

13 Conclusions

Aquifers are found throughout the Bighorn Basin that are capable of well yields of 1000 gpm or more (Lowry et aI, 1976). The Paleozoic aquifer system near the basin margins and the Quaternary aquifers in the Burlington-otto, Wyoming area offer the best potential for groundwater development.

Preliminary evaluation of the Paleozoic aquifer system as a potential groundwater source for the GVID project indicates high cost ($37,000,000 +) for well drilling, water collection and delivery pipelines. Further, areal variability of aquifer char­ acteristics and typical well yields of 25 to 500 gpm suggest that the Paleozoic sequence does not provide a reasonable alternative to the proposed Roach Gulch reservoir.

The unconsolidated Quaternary alluvial deposits adjacent to the Greybull River between Burlington and otto appear to have some potential for groundwater development. A relatively small saturated thickness and areal extent of the deposits and low water table levels in April severely limits the amount of ground­ water that would be available in the early irrigation season. Additional supplies may be available after aquifer recharge (by surface irrigation) has resumed, but wells of sufficient capacity would probably have to be constructed with horizontal drains.

The interconnection of groundwater in the alluvial deposits and the Greybull River suggest that sustained pumping of numerous wells would probably reduce the amount of return flows to the river. Extensive pumping may also interfere with groundwater supplies of existing wells in the area. Either of these condi­ tions could result in regulation of the wells by the state Engi- neer.

14 Biblioqraphy

Cooley, Maurice E. and Head, William J.; 1979; Hydrogeologic Features of the Alluvial Deposits in the Greybull River Valley, Bighorn Basin, Wyoming: u.s. Geological Survey water Resources Investigations 79-6, 38 p.

Fisher, C. A.; 1906; Geology and Water Resources of the Bighorn Basin, Wyoming: u.s. Geological Survey Professional Paper 53

HDR Engineering Inc. and Water Development Commission; October 1988; Guidebook for Water Resources Management and Development, Big Horn and Clarks Fork Basins, 323 p.

Kennedy, Hugh I. and Green, Sharon L.; 1992; Ground Water Levels in Wyoming, 1982 through September 1991: U.S. Geological Survey Open File Report 92-111, 124 p.

Libra, Robert, Doremus, Dale and Goodwin, Craig; June, 1981; Occurrence and Character of Ground water in the Bighorn Basin, Wyoming: Water Resources Research Institute report to u.s. Environmental Protection Agency, 2 vol.

Lowry, Marlin E., Smalley, Myron L. and others; 1993; Hydrology of Park County, Wyoming, Exclusive of Yellowstone National Park: u.s. Geological Survey Water Resources Investigations Report 93-4183; 67 p.

Lowry, Marlin E., Lowham Hugh W. and Lines, Gregory C.; 1976; Water Resources of the Bighorn Basin, Northwestern Wyoming: Hydrologic Investigations Atlas HA-512, 2 sheets.

Peterson, David A. and others; June, 1987; Hydrology of Area 51, Northern Great Plains and Rocky Mountain Coal Provinces, Wyoming and Montana: u.S. Geological Survey Water Resources Investigations Open File Report 84-734; 73 p.

Plafcan, Maria, Cassidy, E. W. and Smalley, M. L.; 1993; Water Resources of Big Horn County, Wyoming: u.s. Geological Survey Water Resources Investigations Report 93-4021, 142 p.

Robinove, Charles J. and Langford, Russell H.; 1963; Geology and Ground Water Resources of the Greybull River-Dry Creek Area, Wyoming: u.s. Geological Survey Water Supply Paper 1596; 88 p.

15 A P PEN D I X

16 Table 1. Lithologic and llydrologic CIUlnlcteristics of Rock Units in the Bighorn Basin, Wyoming. (From Libra et ai, 1981)

Aqulfer System Th I L:kIHHW ,______I r [Ie t 1!.:..r ______....:'!Y!!.ro 1 c Cila r aC' [e rc_I___ _ 2ystem Ernthem anti/or Series G_,e_o_)_o1t!E_~.!~!_L {~~l ______!~~o (~lt!.~---f!~ ~ t

Quaternary: Flood-p Iii I u 0-100 .. Silt, sand, gravel and boulders. ~Ialor.-!'_ql\ff~. Yields >200 RP" 1/1 ~ alluvium ilnd I'rl?:wnl "IIln" iIIul adjoining mil.l0r IHISS I b Il!. cspec tall y where hHh ... ed II .... lIo1ocene & terrace gravel stream channels & trlhulclrJes . recharge frolll divert cd irr iGal iOIl ::J ,'jelRtucene der°tiILs. Tl'rr;u'(Js 50-]On' .. hov(~ presl, .. t waler Ol:CllrS. YtehJs BClier.llly <50 CT -1: fit re!aln l(Jvcls. gpm thrnughout Basin. Terraces are :-. tnl'0grarhlcally high and oft"" ~ IU dnlllwd by seeps and springs alonR «= ~ all es(.~a rpmen t • 41 tj ra Speciric Cnpaclty: 0,1-10 Rpm/ft. :J 0- I'e rml.!ilb 11 t LY : 2.200-4,'.00 t;11J/ ([ ~ Transmissivity: 200-80,000 RPd/fl

----_. Tertiary; ....u 0 ":ocene \11 ll.wood Fill. I , 100- 2 , 'II,\) "Iglaly varlahle. "red-hllncle"" slIlI­ ~ql!.!J'!!.. C:hlcf wilt,'r-yleldlnJ; IInte ~ 0 (IJ- E) .1I1~lItil! Hilllllulullll Illll!rhclhlcil Wllh lIf l he Uppt'r Cruli":I.:ClIItJ-TcrL Llr!" ~ II O·-II,()()() I; IllliIIlIlC. 1II11l1:;lunc, m,,1 IlIc(\ II y AIIIII fer SYIHCIR wiLh yll.'hlu .t"",'rllliv U HIlII. -Hilx.) I·UIII~lullicrilr.ll: cllfil:lllll1nuuuto lH'lWel!ll ')-20 spm lhrulI~h,,"t 1I'" s,.. "lIi ll"IC I CIISCIJ. 1'1' lilt: IIHlll y ",wtn,l Basin. flllll,,1 1.11 thl! cClltral RJtiiu. Srecl£Jc Capacity: 0.01-1.50 gp-/ft

-UHCOHFOfU-11 TV

Paleocene Fort Union FlU. ()OO-J, SOO lIilsal. cllff-fonnlng sandstonc ~q"Hcr. Dcvelorment not ilS exten­ (Polccat lIelleh (~a.J-Cclllra I) m,,1 cong lOlllcrate. over lit III by sive

-_'___ -J __ UHCOHFORtIITY--

Cretaceous: ~q~1 fer. Hot extens lve I y developed. Urrer l.anec Pm. ROO-I,BO!) Hilsstve sand:ltonc overlaIn by ....u Cretllceous (~a.J-IO In[crhctlded cLay~tUl"!, sllt­ Wells locatell l,rlmarlly in Lhe o Blulle. shale ilntl mll10r l:oal west-central and cast-central partR ~ o Sl~'III1~. Forms resistilllt ledges. of the 8asln. l~lowll1H wel1u ln the I/) cen[ral BasIn. Ocr[h to water ...IY ~ ...... he up to 200 feet .atung !lastn lIIarHlns. ,--~---...---,------..,:------,------.. ----.------_.---_._--- Aquifer System Thll"klletw _~l!!.~~ __ -Era_tl;..'e:;.:m;.;....-~--n"'-'~1

1.('lltll"lIlilr, poorly Indunltc,1 flll~­ ~!lI_I.!£C.!.. Hlnor un It of the Upr(>r Upper tlcetc.~ctfle Fill. {j'jO-1 ,20n gr"III(~d (~layey to silty smu)stulle Cretaceous-TertIary Aquifer Systrim. Crctlll'eous (SE-Nl-l) IlIlerlwdded wlth slltstone, cluy­ Few wells ('ompleted tn thls unit in utolle, shale, hentunilc, alld the 8ostn. Yields less thnn IS Rill •• IIIllIor thin coal beds.

A(I'.!!fer. tlesaverde water w(>ll!l tlcslIvcrde Fill. 1 , 100- I ,/100 1I11~hly varlahle sequence o( flll(!­ (tlE-!i ,e) III (-UilrUc-r,ralll(!ti ullntl!:ltollc, slll­ pr imild Iy located In 60uthwl'st lind 1)00-1,/11)0 :llfllle ci.rhllllaccous shale ilIld ,·oid. southclist parts of Dilsln yielding .;20 (1-:-\-1) Trlpartlle c11vl!;lon inlo lower, Rilln (')-10 gplA on the avcrage). f III('-'I~rilllll''' !illlldlltOIlC, mld,lll! III th(lu~h y lclds up to 1.8 gpl" hllve IlIlt~rlH!ddt!tI :;;IIIIIIILlllle ... ,,1 fihnle, Iwell repor l cd. autl upper t:uarse-gr.11nd IHlIldstolle. Specific Capor.it~: 0.75-1.8 gpm/ft

'l,IOO-'I,nO{) I.ow~r half 1I01llinantly dark gray !~~ltlon.!!!....A9.ultard.. Separates the --'.- (NI-I-SE) marine ~hal(!, l~lauc()nlte sllllll­ Upper Cretaceous-Tertiary Aquifer fitllll(!, IIl1d III III bentonite bell!:l System from underlying, JRolated wlll:reils "I'per huH 19 mnlnly luwer tlesozolc '''luUers. In (rac­ 1111 ,~dll~dllcd I~ray, sandy Gha Ie alltl lllred areas and where encnuntering HalltililulIl·. (:unCincd sund6tone beds, yields ul' U to 2n gpm may be ubtained. ·rt -UHCOHFOIU-I ITY- o N !u...!..oJ_~qui fer, ,lrudlll·C o I, ~o- ]()() 1."lItlclIl"r fJnc- to medtllm­ Snndstones III front fer Fm. ....u (W-SE) I~I-i""etl sillld:HUIU! and cunglulllcr­ wall'r under artesian contlit 'uns. "0 ~ alll: ~ilndstonc lJeds alternating "0 l'oruRlty: 10-26% 2 ;: wllh HlliIlc anti Icsser amounts uf ",!rtncab' 11 ty: 0-1.4 Klld/ f t hcnlUlIILe. "0 III Tran~QllsHlvlty: 0-100 ~1"I/h2. C W i-UHCOHFOlttlITY-- ...... IU w·... )70-1- SlIlceuus hrittle shale with thin Aqllltard. Yields watC'r Im·ally IU :J Lower Howry Shale ) 0- sfIIHlstonc and bentun I te beds in in fracture zones. '.)~ Cretaceous ...l the uppl~r part. I U UTi Ti 0 o N shale with hentunlte beds and Aquitard. Huddy Sandstone m~mb~r N 0 The rmopn ll!i (JOO-M)O sort o III salldy alld silty zOlles. Huddy sand­ yleld~ minor amounts IIf W'lter. IU IU Sha lEo (NI-I-S) ,....:;: stone IIIclIlhcr, approxlmately 40 feet p... lhlc.:k, ahout 20U feet ahove hase. W IU ~Aqu t r er. I'rodu('es W3 rer under Po Cloverly Fm. 8'j-/e70 Composed or t.hree unlrs, nn "pper arL(!fd,1Il pre:.sure, primarily frUlA ~ (~;E-N\.J) SiliHlslulIl', n IIIlddle Rh.Jle, 31111 a luwl'r ICllllndar conglomeratIc: uPllcr sandstone. Y le Id ±2 ~t' gpm. I.and:;! Olll' I'oroslty: 7-1')% lind up til 2.2 l~pd/ft2 (120 md) TrrllHillllsslvity: 0-6 gpd/ft anel uI' La 50 gpd!rt -fahlE-1 1.. (COl-it: :i_ nUF~d) ------A'1 uircr System TIa ll:klwss ~~ltl.«:..._I_JI!Lt______(!i.L ____ .______l~~~,I~(_~tc~fi.LC~!!1.a:,n.£.Lc..r J~~1~s..!.£.....!!.!!!!~t~:.r:.! ~nl ~rathem and/or Series Ceol ______

-UNCON FORI-II TV- Jurassic Horrls un Fill. 7';- Jon Varlel~ .. rc,1 smltly RIaale an,1 Rlud­ ~~!_n~.r_~(l~I_L!.£.r.. Santi stun&! llL'd s p ro- (NIJ-S) slune willa lCllses of flne-erilined llll!:&! 6111a1l yields where Lhey ufC sanaltlt(llw. (:unglllllll!r;alc iIIul cXlcnsj,,&!. I I IIIl!SI.IIIWS • I'nrnslty: 15%±

Sundlln "',' 1'111. 1001 l:rily-grC(~1I :llaal (! J IIrerhcdllcd wi til ~~l.!!.'!!-Aq~~lf cr. S.uHls tOil&! I ilyt.'rR liillllisLUlW i1lhl hl"llwn fn:wlli("rUlJ:i I'rllallln~ lilllilil ylcltls. IllIIl!litOlW,

u Gypsum Srr lug:; Fill. 21S-1I0 lied !;llls'onc and l.halp. with nr(lY ~!~!!~.!"~~l~!!!.e.!.. Soillt lnn wnes In rl TriaRSic "U U (E-Il) Lo hrowlI IIUII!SLIIIIC I.Jcds iIIltl I:YIHilll1I heds y leid sma 11 amounts of "0 .... orl 0 1IIi1:;:-; I ve ltv II!' 11111 huds, wal('r. ~ N 0 "0 1/1 - UNCONFORN JTY- s:: 1/1 U ~ :J: " u Chugwa rer FIll. la ,)()-I ,000 Jnl.{!rhl!llllcti relll tlhll"~Y siltstone m...!IE..~_A'l~Uer. SandsloneH ilnd ~ ..... u .... (NE-S) mill f 11ll~-nralllc" sand:.tlluc with nYlltillnt hcdli produce sma I l 1IR1llllnl tI 'l=- 0";:J lHIl' 111II(!Hla~IW heal In tlw t;oullwrn (II art"tilun Willer loc.t! Iy. ~< I l'ill't IIf I he lIau III. Cuntilins U U Itoros It y: 1 ')-22% orl orl :>lIl11e IWIHlIIIII. o 0 Itcrllll!i.hlilty: U.'.-2.2 r.lllIJrl"l. N N o 0 (up Lu 11U lilt.!) U 1/1 rl U Transmissivity: 5-40 Kpd/fl ":': 11-

~ Ulnwon dy rill. 0-100 Th I n-hetlded I. lit y slw I e and Not: generally considered &In u a. slltstune. Ul'per rart contains ll'JuHer. a. p SUIII(' I I 1Il(!Stont! and gYPSUIII.

Permian l'hoSl,h urfa Fill. IOO-JOn ,In the eastern rart of the basin t I.e'!.ky C()nfll!l!!.8-"~!!. Some (;,,:ics (N-SE) lhe 1'1101> 1'110 r 1a C:UIISJ slS of a produces gruunJ walt.'r under 5hale tlnd slJlslonl! se(luence wltla arlesLan t:ulldlt:ioIl6. 1 illl(!stollc tlild ~ypsllm bcds. III ~oroslty: 2-24~ lhe we:Hern naslll It is a sandy "crmeabillty: common!y

------....------_._---_._- -'- --.--.----.. -_._ .. _-----_._._------Aquifur Systcm Th I t'kllcss 2Y~~ ____--=.I·::..:r..;a::..;t:;I.:.:IC::;.m:::.....-I:---=.;u:.:.;n;.:d;.;.I-.:..:)r:-;S::..·e::...::..r.;..l.;..c.;..s-_. ___(-:c.;.. •• _,_I.~!.!..~-- _. __ .____ .1! ~ 1__ _. ____ . ___~~U~!. ~~Jl!.£.E!!.) rilc:ter______!!l'.c!!~~ol> Ie CI~lr&lc[l!r-~ ______

-UNCONFOIUI I TY- H •• 'nr IUluHer. Artelilim wulls uhen 1'enslccp S 7 -f.OU Tun til white, lIIassJvu, t~rtl!.l::J­ Pcnnsylvanian flow LIt thc surfacc with yluld21 Sandstone (NIJ-:a:) hCllth!tI liilnJ:;l:OIlI!. Luwer part mure dolollllll! wllh lnlerhecldud carhun- cOlllmonly 50 lo 200 Rpm. ar ale bcds. Prlillilry JnLcrgrllllul Porosity: 3-26% 2 porn:; II y mill lWI~Olld .. ry fnl(; lurc l'ernwablUty:

~lt!cnvcrJ-1t"t~\l)(I : TrallslIIl ss I v It y: 400-3,000 Cplil ft 8:~IYS Ica 1 tlethuds:': 2 I't!rmcabllhy: 0.02-tl. cpd/fL (1111 lo 800 till!) & II Transmhslvlty: 7-L,I!(}0 GJld/ft p ~. tl.!.!lor AJIuJ fer. Uarwln sandstone en Amt.iden 1"111. 117-:100 Itc!d sl ... le allli c1ulumlte willi churl ... U (lnl··I·: ) ullcI tlc:c:.,:iI UIlII I I~YlwlllII. Uurwln mcmher y h·ldu wllt,!r undcr I,relluuru. II 'rl ... o lJillIIIIlLIIIIC mClllllt!r ;at IIiISC ...1I11;es ori N I'oros I 1 Y : WZ± :J o III llalc:kllCHS I rOIll 0 to 1)0 fct!t. CT II -UNCONFORHI'l'V- r-i -< III p.. !.!!!J0r Aquifer. ArtesIan, yleldll tIt ....U tHsslssippian HCldlson HUn-JOO Hafislve crystallinc limcstollc and o dolumlte wILla siJlstone and shalt! ) ,000 tpm, but usually lesH. N Limestonu (NW-$E) o ;tOIlCS, clat!rly In places. Ilrecc:la II Porosity: 10-20% rl filled jlilleukurs[ In "PI,er Ilurl 1 III l'urmcahJllty: 0.4-0.6 cpd/ft p.. illlcI a sCI:oud hrc!c(: J a ZOIiC In TrillltimJ ss' v, t y: lltwa 11 y 7-I,Onn IIIlcltllu. Sct:ollliary puroslty due tn lWd! ft to JO ,000 slIlullun allllle JollllS and fractu ....!s. Kpd!ft when: hlghly fractured -UNCONFORN lTV--

Slllstllnc. Iiolumllc and IImcstonc ~()lIltllrd. Not ecnurally considered DevonJan 1'hrce Furks­ JOU-() llll uClllifcr. Jeffersoll Fm. (rH~-~i\n willi green ilnd hLllck fihalcs ilnel (und Lv ltled) s J I ty 110 I omlll! In lhe westcrn "ill·t of lhe nasln. -UNCONFOltfol lTV--

~qul fer. Jlrud .. c:cH lIrtuli Ian wilt,,'r OrdovIcian BIghorn II ')()-o tlusslve tu thln-hcdded dolom1Lt! J n CIrCUli of f rat'lur llle and till) ut Inn. Oolulllltc (tlll-SE) and dolomJt(! limestone • .,·ine- 1~I'itlnetl ilia liS I ve sandstone LIt thc I'oros I ty: 1J~+ hm,e. "orns I ty Jlr IlIlar J ly due to fl-actllrlllC ulld solution. Contains CilvenlClllS zunes ncar outcrup ill·C'W.

l\J o TablF~ 1 .. (con t :i. nl.ted )

Aquifer System 'I'll I ekn(lSS .2!!.tem Erathem and/or Series __C_'!.'ll.~!&!~~_~.I1_~ 1: _____ . ____ ~LU ____. ___

-UNCONFOIUIITY-

Cambrinn GnU at In/ 1,100-900 SI lale, flat Jll!hhle (!onglomer,ltl' ~~~~-'..!J.!.~!~. Ult;persed sillhl~ IlIlerlwclli t Gros Ventre fin. (UE-S\-I) ,II Itl I Ime!ilollc tie(I"CIH~e. lUay y II! It! slIIall qu,Ult J til!:> uf wllt~r. ~...... u (untlivilled) (; rlls VClltrc cOlltallllO bentonite :J 0 CT N II c,I!!. .-:: 0 -u u :-) -.III Flathcllt! 0-170 rI((Hilc .11111 'I'Hlrtzll Il' Halllltaolw ~!I~Jfer. l'ruduccR watt!r Uliliur 11 P. ..t: SlIIuhaollc (NE-!iW) "w Itll IlIrl!.hed,I(!11 t;hales III lIlt! VL"'Y hleh Ilft(!:;Ian pftHitWfl', !.Iulc u III III 'pcr "ilr L. dala avnJI"hle 1111 hytlrulot:lc r-i chilracterlstIcs. Jte(lortetl yields '"' ~(lm. , of over 2,000

::NCONFORMlTY-

~ ...III ~ .tl G Co r,Ul I t I (~ and III(! t a-sed I men t ary I.ocally yields small amountR of III u r, ,ck:i. water [0 wells ...QI Cl. ECONOMIC COSTS OF THE NO ACTION ALTERNATIVE Am 0 2 94 WATTS & AsSOCIATES, INC. 1472 NORTH snf STREET, SUITE 105 .- - - . -. ': 7· . ·7~.:.;: "?~±:ONE ECONOMIC RESEARCH ~, ~O~G82070 ill AND CONSULTING _~ ... -3Q 742·7881 SERVICES TELECOPIER 307·742·7882 MEMORANDUM

To: GEl Consultants, Inc. Re: Economic Costs of the No Action Alternative for the Greybull Valley Project Date: August 1, 1994

1.0 Introduction

Under current ope rat i ng condi t ions, Upper and Lower Sunshi ne Reservoi rs are not able to deliver adequate supplies of irrigation water to the GVID in many years. As recently as 1988, approximately 50 percent of the irrigated lands in the Lower Basin experienced crop failures due to a lack of late season water supply. As a result, there are significant economic costs associated with the No Action alternative to the proposed Greybull Valley Dam and Reservoir Project.

The Draft Conceptual Design Report for the Greybull Valley Project contains an economic analysis of project benefits and costs based upon the average value of irrigation water in the project area (GEI,1993). That assessment was based upon the estimated difference between returns to irrigated farming and returns to dryland agriculture in the Greybull Valley. That approach provides reliable est imates of the benefi ts of bri ngi ng new 1ands under i rri gat ion. It also provides benefit estimates for supplemental water supplies in situations where water shortages are not severe enough to cause crop failures.

In situations where crop failures occur, however, economic costs can be significantly greater than the average value of irrigation water. The reason is that irrigators that lose an entire crop suffer a larger loss than they would have by not irrigating. In this situation, significant production expenditures are incurred during the growing season, but no revenue is generated to offset those expenses. In economic terms, the cost of a crop failure can be expressed as the difference in farm income between a full water supply scenario and a crop failure scenario; i.e.,

Full Water Supply farm income = value of crop - sunk production costs - variable harvest costs Crop Failure farm income - sunk production costs Difference = value of crop - variable harvest costs

Thus, the appropriate way of estimating the economic cost of a crop failure is to subtract variable harvest costs from the value of the crop that was lost.

Estimating the total economic costs of the No Action alternative involves estimating the extent and frequency of water shortages under current conditions, and then estimating the cost of those shortages. The methodology necessary to make such estimates is similar to that used to estimate the economic cost of agricultural flood damages. The application of these methods to water shortages in the Greybull Valley is described in the following subsections.

1.1 Frequency of Shortages

The first step in the analysis was to estimate the frequency and magnitude of i rri gat i on water shortages in the GVID. States West Water Resources Corporation (SWWRC) provided estimates of shortages under current conditions for the 2, 5, 7, 10, 12, 15, 20, 25, and 30-year recurrences, which are depicted graphically in Figure 1. Because the economic analysis requires estimates of shortages over a continuous interval, a linear regression line was fitted to the data using least squares techniques. The resulting regression equation is:

Y = -3,964.09 + 3,489.91 X where Y = shortage in acre feet X recurrence frequency in years 2 FIGURE 1 GREYBULL VALLEY IRRIGATION SHORTAGES Current Conditions

Shortage (1000 AF) 100 •

80 •

,/ ./ 60 w

40 •

20 •

O~----~----~----~------L------~----~----~ o 5 10 15 20 25 30 35 Frequency (Years) The R2 value associated with the regression line is 0.97, meaning that knowledge of the recurrence frequency explains 97 percent of the variation in irrigation water shortages, a good fit to the available data.

1.2 lower Basin Costs

This subsection describes the analysis of No Action alternative costs for the 48,000 irrigated acres in GVIO along the lower Greybull River.' The first step in the analysis was to estimate the number of acres subject to crop failure as a function of the magnitude and frequency of water shortages. According to Dave Edwards of the GVIO, the 1988 drought resulted in the loss of slightly over 50 percent of all irrigated beets, beans, and barley in the Lower Basin, and a substantial portion of the alfalfa hay was limited to one cutting (Edwards,1994). Accord i ng to SWWRC' s hydro log i c model, i rri gat i on water shortages of 1988 magnitude or greater will occur at 11.8 year intervals, on the average, in the Greybull Valley.

Table 1 presents estimates of lost crop production due to irrigation water shortages in the Lower Basin. The information in the second row of the table corresponds to the effects of the 1988 drought. During that year, approximately 6,000 acres each of beets and beans, and 8,000 acres of malt barley were lost. An additional 4,000 acres of alfalfa was limited to one cutting rather than the usual three.

The remaining entries in Table 1 were generated assuming that crop losses at other recurrences woul d be proport i onate to the 1988 losses, wi th some restrictions. First, it was assumed that beet and bean losses would never exceed 8,000 acres each regardless of the magnitude of shortages. The rationale for that restriction is that these crops involve higher production costs and are more vulnerable to late season water shortages than barley or alfalfa. As a result, i rri gators are more 1 ike 1y to restri ct acreages of these crops when wi nter

The division of GVID irrigated lands into 48,000 Lower Basin acres and 16,800 Upper Basin acres is the same convention employed by SWWRC's hydrologic model. Previous economic analyses of the Greybull Valley Project have focused on the 33,500 irrigated acres along the Farmers and Bench canals. 4 Table 1 Estimated Frequency and Extent GVID Crop Failures - lower Basin

Crop Losses (Acres) Frequency Shortage Alfalfa Alfalfa (Years) (A.F.) Beets Beans Barley (2nd cutting) (3rd cutting)

10.5 24,300 5,300 5,300 3,500 11.8 27,400 6,000 6,000 8,000 4,000 4,000

13.3 31,500 6,900 6,900 9,20~ 4,600 4,600 15.4 36,800 8,000 8,000 10,700 5,300 5,300 18.2 49,500 8,000 8,000 14,500 10,800 10,800 t.n 22.2 54,500 8,000 8,000 15,800 16,200 16,200 >25.0 >54,500 8,000 8,000 15,800 16,200 16,200 snowpack has been 1 i ght. I rri gat i on water avail abi 1 i ty cannot be pred i cted re 1 i ab 1y, however, because much of the storage in Upper and Lower Sunsh i ne Reservoi rs resul ts from 1ate spri ng storms that occur after the plant i ng date for these crops. As a result, substantial acreages of beets and beans will continue to be at risk of failure.

The other rest ri ct i on used in generat i ng the data in Table 1 is the assumption that water shortages of less than a 10-year recurrence magnitude do not routinely result in total crop failures. That assumption is based upon the fact that the magnitude of shortages drops off significantly at less than 10-year recurrences, and irrigators have some flexibility to stress their forage crops and get at least some yield out of their higher valued crops when shortages are not too severe.

The second step in the analysis was to estimate the value of crop losses and the variable harvest costs associated with each crop. The estimates of lost crop val ue were taken from the Conceptual Des i gn Report (GE 1,1993) . The est imates of vari abl e harvest costs were deri ved from enterpri se budgets developed by the University of Wyoming for the Worland area (UW,1986) and the Powell area (UW,1991). The results of the analysis are presented in Table 2.

Table 2 Estimated Costs of GVID Crop Failures

Value of Variable Crop Lost Crop/ Harvest Costs/ Lost Acre Acre Income/Acre

Sugar beets $841.82 $102.65 $739.17 Beans 513.69 38.81 474.88 Malt barley 319.50 28.87 290.63 Alfalfa (1 cutting) 114.34 25.09 89.25 Alfalfa (2 cuttings) 228.67 50.19 178.48

6 The last column of that table gives the estimated economic loss (crop value minus variable harvest costs) associated with crop failures on a per-acre basis. The costs range from a high of approximately $740 per acre for sugar beets to $90 per acre for one cutting of alfalfa.

Estimates of the total cost of irrigation water shortages in the Lower Basin are presented in Table 3. These estimates were derived using an interval estimation technique that approximates the results of integration to measure the area under a damage curve. Approximate methods were used because the relationship between exceedance values expressed as probabilities and damages is non-linear and the form of that relationship is unknown. The linear relationship between exceedance values expressed as years and damages, depicted in Figure 1, was used to generate the average shortage figures in Table 3 for each exceedance interval. The average cost data in Table 3 for the 10-year and greater shortages (exceedance values >.100) were derived by multiplying the cost data in Table 2 by the appropriate acreage figures in Table 1. For shortages with less than a 10-year recurrence value. the average value of irrigation water in the Lower Basin -- $37.39 per acre foot -- was used to estimate average costs.

The results in Table 3 indicate that the average cost of water shortages can range from approximately $105,000 (at slightly greater than two-year intervals) to as much as $17.1 million (at 25-year intervals or greater). The expected annual cost of water shortages was calculated by multiplying the exceedance values by their respective average damages, and then summing the results. The annual expected cost of the No Action alternative for the Lower Basin is approximately $1.5 million.

1.3 Upper Basin

The cost of water shortages along the upper Greybull River is more difficult to estimate because less information is available concerning the effects of the 1988 drought, and because the predominant crop in the Upper Basin is hay, which seldom suffers a complete crop failure even under severe water restrictions. An approximation of Upper Basin costs was developed, 7 Table 3 Estimated Cost of Irrigation Water Shortages - lower Basin

Exceedance Average Average Expected Value Interval Shortage Cost Cost

.500 .400 .100 2,800 $104,700 $10,470 .300 .100 4,400 164,500 16,450 .200 .100 7,400 276,700 27,670 .100 .100 14,300 534,700 53,700 .090 .010 24,300 6,746,800 67,470

CD .080 .010 27,400 10,323,300 103,230 .070 .010 31,500 11,871,700 118 720 .060 .010 36,800 13,768,100 137,680 .050 .010 49,500 15,854,200 158,540 .040 .010 54,500 17,195,700 171,960 .030 .010 70,900 17,195,700 171,960 .020 .010 100,400 17,195,700 171,960 .010 .010 >100,400 17,195,700 171,960

.005 .005 >100,400 17,195,700 85 2 980 Expected Annual Cost $1,467,750 however, using assumptions similar to those used for the Lower Basin; i.e.-­ the 1988 drought resulted in the loss of one cutting of hay on approximately 50 percent of irrigated land, and hay losses for other events occur on a proportional basis. It was also assumed that shortages that occur at less than 10-year intervals may reduce yields, but do not reduce the acreage harvested.

The estimated frequency and extent of Upper Basin crop losses is given in Table 4, which indicates that for shortages ranging from the 10- to 25-year event, between 7,400 and 16,800 acres may lose one full cutting of hay. The cost of one lost cutting was valued at $89.25 (Table 1), and for shortages of less than 10-year severity, the average value of water in forage production ($15.26 per acre-foot), was used to estimate losses.

Table 5 presents the estimated costs of the No Action Alternative for the Upper Basin. The results were derived using the same analytical procedures as for the Lower Basin. The results indicate that the average annual cost of water shortages in the Upper Basin is approximately $130,000.

1.4 Summary

The estimated economic costs of the No Action alternative for the Upper and Lower Basins combined are presented in Table 6. The results in that table indicate that the expected annual cost of water shortages in the GVID is approximately $1.6 million under current conditions. The present value of those costs, assuming a 4 percent discount rate and a 50 year time period, is $34.3 million.

It should be noted that these cost estimates reflect the direct economic costs of the No Action alternative. All of the alternatives under consideration, including the No Action alterative, also have indirect economic implications for the regional economy. These indirect effects have not been considered in the present analysis.

9 Table 4 Estimated Frequency and Extent GVID Crop Failures - lower Basin

Frequency Shortage Alfalfa Acres {Years} {A. F. } {one cutting}

10.5 8,500 7,400 11.8 9,600 8,400 13.3 11,100 9,700 15.4 12,900 11,300 18.2 17,400 15,200 22.2 19,100 16,800 >25.0 >19,100 16,800

Two other things should be noted with respect to the results summarized above. First, the proposed Greybull Valley Project may not eliminate all of the water shortages that exist under current conditions. The extent to which shortages will be alleviated is a function of irrigation water demand, the manner in which irrigators utilize their additional storage, and operating restrictions that are imposed upon the project.

It is equally important to note, however, that the proposed project will have benefits that go beyond the simple alleviation of shortages. By increasing the total amount of storage in the Basin, irrigators can expand their production of higher valued crops, such as beets and beans, and have more assurance of late season water to finish those crops. Although some shortages to demand may continue to exist, they are more likely to accrue to forage crops, which have a lower value.

The project's proximity to irrigated lands in the Lower Basin will also allow more efficient use of irrigation water, which can increase returns per acre-foot of storage above current levels.

10 Table 5 Estimated Cost of Irrigation Water Shortages - Upper Basin

Exceedance Average Average Expected Value Interval Shortage Cost Cost

.500 .400 .100 900 $13,700 $1,370 .300 .100 1,600 24,400 2,440 .200 .100 2,600 39,700 3,970 .100 .100 5,000 76,300 7,630 .090 .010 8,500 660,500 6,610 ra .080 .010 9,600 750,700 7,510 ra .070 .010 11,100 865,700 8 660 .060 .010 12,900 1,008,500 10,090 .050 .010 17,400 1,356,600 13,570 .040 .010 19,100 1,499,400 14,990 .030 .010 24,900 1,499,400 14,990 .020 .010 35,300 1,499,400 14,990 .010 .010 >35,300 1,499,400 14,990

.005 .005 >35,300 1,499,400 72 500 Expected Annual Cost $129,310 Table 6 Estimated Cost of Irrigation Water Shortages - Upper and Lower Basins Combined

Exceedance Average Average Expected Value Interval Shortage Cost Cost

.500 .400 .100 3,700 $118,400 $11,840 .300 .100 6,000 188,900 18,890 .200 .100 10,000 316,400 31,640 .100 .100 19,300 611,000 61,100 .090 .010 32,800 7,407,300 74,070 .080 .010 37,000 11,074,000 110,740 ....l\.) .070 .010 42,600 12,737,400 127 370 .060 .010 49,700 14,776,600 147,770 .050 .010 66,900 17,210,800 172,110 .040 .010 76,600 18,695,100 186,950 .030 .010 95,800 18,695,100 186,950 .020 .010 135,700 18,695,100 186,950 .010 .010 >135,700 18,695,100 186,950

.005 .005 >135,700 17,195,700 93 2 480 Expected Annual Cost $1,596,810 References

Edwards, David W., Memorandum to Gary Watts entitled Effects of Water Shortages on Crop Production, July 20, 1994. GEl Consultants, Inc., Draft Conceptual Design Report, Greybull Valley Dam and Reservoir Project, Level II, Phase V, report to the Wyoming Water Development Commission, July 1993. University of Wyoming, Cost of Producing Crops: Worland Area, Wyoming, 1985- 1986, Cooperative Extension Service, Laramie, Wyoming, July 1986. University of Wyoming, Enterprise Budgets, Powell Area (Various Crops), Cooperative Extension Service, Laramie, Wyoming, August 1991.

13 DEVELOP:MENT OF ESTINIATED TOTAL PROJECT INVESTMENT APPENDIX C DEVELOPMENT OF ESTIMATED TOTAL PROJECT INVESTMENT

Reconnaissance level total project cost estimates were based on the WWDC general cost estimating formula which is shown in Table C.1. Construction quantity and reservoir area­ capacity information was developed from USGS 7.5 minute quadrangle maps. For consistency, unit costs and the costs of key project components were developed to be consistent with those developed in the conceptual design of the Lower Roach Gulch Dam and Reservoir [GEl, 1994-2]. Where this approach was not applicable, costs were estimated from our database of similar bid tabs, cost estimates, contractor quotes, and the Means estimating guide. Consistent with the previously prepared conceptual design cost estimate for Lower Roach Dam and Reservoir, all construction costs have been calculated in 1992 dollars and have been escalated to 1995 dollars for estimating total project investment.

Development of reconnaissance level costs for mitigation of environmental, social, and other impacts was beyond the scope of this contract. Therefore, previously developed cost estimates for this phase of project development at Lower Roach Gulch were used. If these costs are significant, the costs presented in this report could change substantially. Furthermore, additional geotechnical investigations, engineering evaluations, and water supply modeling would be required for those primary projects that have not been completed to a conceptual evaluation level. Therefore, estimated investments reported in this document may need to be modified in the future to reflect the results of these analyses. Also, land acquisition costs were estimated based on a preliminary estimate associated with lands impacted by alternative projects. The impacted lands were classified as follows:

• Irrigated farmland ($1,000 per acre) • Badlands ($150 per acre) • Scenic value lands upstream of Meeteetse ($2,000 per acre) • State or Federal government land (no cost)

This information was provided by Mr. Dave Edwards of the GVID and was considered adequate for a reconnaissance level of study. A summary of the development of total project investment for all alternatives is provided in Tables C.2, C.3 and C.4.

94071\REPOR1\TEXT. VI C-1 TABLE C.I GENERAL COST ESTIMATING FORMULA

Final Design (6% of CCS No.1) Permitting and Mitigation Legal Fees Acquisition of Access and Right-of-Way

Project Components Component A Component B Component C Component D Component E Component F

Mobilization (6%)

Construction Cost Subtotal No.1 (CCS No.1)

Engineering Costs (10% of #1)

Construction Cost Subtotal No.1 (CCS No.2)

Contingency (15% of #2) Construction Cost Total

TOTAL PROJECT COST(1)

Notes: (1) All project costs are presented in 1992 dollars to be consistent with previous cost estimates.

94071\REPOR1\TEXT.V1 C-2 8119194

TABLE C.2 SUMMARY OF ENLARGEMENT & OFF-CHANNEL INVESTMENT

Final Design (6%of CCS NO.1) Pennitting and Mitigation Legal Fees Land Acquisition

Project Components Component A Component B Component C Component 0 Component E Component F Mobilization

No.1 Engineering Costs (10% of '1)

No.2 Contingency (15% of '2)

1992 Total Construction Cost 1992 PROJECT COST 1993 PROJECT COST 1994 PROJECT COST 1995 PROJECT COST Annual O&M COST Equiv, Storage Shares

(75%) WWDC Grant (25%) GVID Cost Annual GVID Cost

Annual Cost if 5,000 Shares Sold Annual Cost if 10,000 Shares Sold Annual Cost if 15,000 Shares Sold Annual Cost if 20,000 Shares Sold Annual Cost if 25,000 Shares Sold Annual Cost if 30,000 Shares Sold

GVCEMS')

TABLE C.3 SUMMARY OF MAINSTEM DAM INVESTMENT

(6°hof CCS No.1) Permitting and Mitigation Legal Fees Land Acquisition

Project Components Component A t-:-~---,-~­ Component B f---=----="-­ Component C ~~~~:.-. Component 0 ~~~~:.-. Component E ~:..::-::~~:-­ Component F ~:....-...~~_ Mobilization

No.1 Engineering Costs (10% of #1)~~~~~

No.2 Contingency (15% of #2) t--;....-~--

1992 Total Construction Cost 1992 PROJECT COST 1993 PROJECT COST 1994 PROJECT COST 1995 PROJECT COST Annual O&M COST Equiv. Storage Shares

(75%) WWDC Grant (25%) GVID Cost Annual GVID Cost

Annual Cost if 5,000 Shares Sold I---__.,..-~ Annual Cost if 10,000 Shares Sold t---=::~:----t Annual Cost if 15,000 Shares Sold I--~~:----t Annual Cost if 20,000 Shares Sold I--""""",,,~_~ Annual Cost if 25,000 Shares Sold I----,,-,~,.--_I Annual Cost if Shares Sold

GVCEMS.xLS C-4 GEl Consultants, Inc. 8119194

TABLE C.4 SUMMARY OF NON·STORAGE PROJECT INVESTMENTS

Final Design (6%ofCCS No.1) Permitting and Mitigation Legal Fees Land Acquisition

Project Components Component A 37,928,532 Component B I--~---:' __ Component C 1-----­ Component 0 t----::---­ Component E t----:::---­ Component F ~~-::--::-::-::_ 1 ______M_o_bilization (6%)1~ __~

No.1 Engineering Costs (10% of #1)~~~~_

No.2 Contingency (1 5 % of #2) 1--___--'- __

1992 Total Construction Cost 1992 PROJECT COST 1993 PROJECT COST 1994 PROJECT COST 1995 PROJECT COST Annual O&M COST Equiv. Storage Shares

(75%) WWDC Grant (25%) GVID Cost Annual GVID Cost

Annual Cost if 5,000 Shares Sold t--~~::--_t Annual Cost if 10,000 Shares Sold t--~~-_t Annual Cost if 15,000 Shares Sold I------f Annual Cost if 20,000 Shares Sold t----:-::~~_t Annual Cost if 25,000 Shares Sold t---=~~_t Annual Cost if 30,000 Shares Sold

GVCEMS.XLS C-5 GEl Consultants. Inc. DEVELOPl\ffiNT OF ESTIMATED PROJECT YIELDS APPENDIXD DEVELOPMENT OF ESTIMATED PROJECT YIELDS

Project yield is the amount of additional water that could be captured and made available to provide supplement irrigation water during an average year. Yield increases as a function of demand. In other words, when there are higher demands on the reservoirs, more water is released providing additional storage capacity to capture excess flows, if available. Periodic irrigation shortages will also increase with increased demand. Another important consideration is minimum streamflows or minimum bypass flows at diversion dams intended to protect or enhance fisheries or other resources. This can have a dramatic impact on project yields as illustrated in Table 0.1.

Scenario A represents the existing condition in which the average annual yield from Upper and Lower Sunshine Reservoir is approximately 43,800 acre-feet. On average, irrigation shortages of about 14,000 acre-feet can be expected once every five years under this scenario. Scenario B illustrates how the total yield increases by approximately 19,000 acre­ feet to 62,800 acre-feet under high April demands. This occurs when more farmers raise sugar beets that require greater water usage in April and later in the growing season. Under this higher demand scenario, five-year irrigation shortages also increase by approximately 34,000 acre-feet to nearly 50,000 acre-feet. Because of these dramatic shortages, most GVID farmers are reluctant to take the risk of planting high cash value, water intensive crops such as sugar beets and dry beans. Hence, this demand scenario is unlikely without additional water supplies.

A comparison of Scenario A with Scenario C shows the impact of a 30,000 acre-foot Lower Roach Gulch reservoir. The reservoir will provide an additional yield of 26,500 acre-feet. Total systemwide yields increase by approximately 30,000 acre-feet to provide a total of yield of approximately 74,000 acre-feet. More importantly, the irrigation shortage expected once every five years is reduced by approximately 6,000 acre-feet. The assurance of a more reliable water supply will allow the GVID members to plant higher cash value crops with much a lower risk of crop failure.

Scenario C assumes moderate minimum streamflow requirements that were discussed with the WG&FD on a preliminary basis during Phase IV and V evaluations. However, more stringent recently proposed requirements for Scenario C are shown as Scenario D. These additional bypass requirements reduce the Lower Roach Gulch yield to approximately 24,000 acre-feet, but five year shortages increase to nearly 15,000 acre-feet. These shortages would be greater than the shortages which currently exist under Scenario A. Minimum streamflow requirements have not been fmalized with the WG&FD, but this comparison shows that these requirements will be crucial to the overall capability of a storage project to effectively reduce irrigation shortages.

94071\REPOR1\lECT.V1 0-1 Systemwide modeling of each alternative was beyond the scope of this study. Where possible, yield estimates were extrapolated by SWWRC from the systemwide water resources model completed during Phase IV and V of the project development cycle. Where this was not possible, data was extrapolated from previous model results, adjusted by drainage area, or estimated from other data sources. Estimated yield for each alternative are provided in Table 4.1.

An interesting conclusion of data extrapolations was that there may be an additional 50,000 to 80,000 acre-feet of divertable excess flows available during an average year from the Upper Greybull or Wood Rivers. However, as shown on Table D.2, most of this water is only available during June and July when the river fluctuations are extreme. We have made some preliminary yield estimates based on this data; however, a diurnal analysis of diversion data would be required by to make a defensible yield estimate. This analysis is beyond the scope of this reconnaissance level evaluation, but would be important in the assessment of the overall feasibility of the Upper and Lower Sunshine Reservoir enlargements and the Rawhide and Spring Creek projects.

94071\REPOR1\1EXT.VI D-2 TABLE D.l SUMMARY OF LOWER RESERVOIR DEMANDS AND SYSTEMWIDE YIELDS

Upper Sunshine Reservoir (AF) 15,910 32,890 18,250 18,500

Lower Sunshine Reservoir (AF) 27,850 29,880 29,200 28,400

Lower Roach Gulch Reservoir (AF) 26,510 24,200

Total System Yield 43,760 62,770 73,960 71,100

Two-Year S (AF) 1,550 10,840 910 1,200

Five Year S (AF) 14,065 48,160 8,030 14,800

Assumed Minimum Stream Flows At Sunshine Diversion (cfs) 5 At Wood River Diversion (cfs) 25 30 At Lower Roach Gulch Diversion (cfs) 35 40 Minimum Pool at Upper Sunshine (cfs) 5,000 5,000

(1) Assumed minimum streamflows from Phase V evaluations. (2) Minimum streamflow conditions proposed by Wyoming Game and Fish Department, January 1994.

9407I\REPOR'nTEXT.VI D-3 TABLE D.2 ADDITIONAL FLOW AV AILABLE FOR DIVERSION NEAR EXISTING SUNSHINE AND WOOD RIVER CANAL DIVERSIONS

Oct 0 80 1,636 259 1,943 1,482 Nov 0 167 1,094 512 1,392 2,218

Dec 0 45 703 178 1,010 1,735

Jan 0 14 509 72 816 1,558

Feb 0 12 453 54 730 1,320 Mar 0 22 586 103 894 1,542

0 0 66 0 80 55 787 376 2,236 431 2,475 1,136

21,894 11,605 25,090 12,138 25,374 13,844

717 3,181 12,840 3,463 13,075 4,599

0 0 91 10 112 84

0 0 0 0 0 0

Total 33,399 15,503 45,304 17,220 47,902 29,572

1) All values shown are in acre-feet. 2) Assumed minimum streamflow requirements.

94071 \REPOR1\TEXT.VI D-4 Meeting set on Greybull dam By TOM MAST Star-Tribune staff writer

GREYBULL - A dam and reservoir proposed by the Greybull Valley Irri­ gation District to provide additional late season water for farms in western Big Horn County will be the focus of a meeting this week in Emblem. The U.S. Army Corps of Engineers and the U.S. Bureau of Land Manage­ ment, both of which must approve the project, will prepare an environmen­ tal impact statement. The proposal calls for construction of a 150-foot-high, zoned-earth em­ bankment dam at the lower end of Roach Gulch near the Greybull River. The proposed dam site is located on private land. The dam would be about 1,700 feet long, with a 150-foot-wide earth chan­ nel spillway. The reservoir created by the dam would hold approximately 30,000 acre-feet of water, according to a scoping notice. Water to fill the reservoir would be diverted from the Greybull River by a small diversion dam and carried to the proposed reservoir via a six-mile-long supply canal. The diversion dam would be designed to allow stream flow by­ passes and passage by fish. A public scoping meeting for the project EIS will be conducted Oct. 26, 7 p.m., 3400 Road 10, in Emblem. Members of the public are being asked to help identify issues which should be addressed in considering the proposal. The Wyoming Water Development Commission has screened several al­ ternatives to the proposed project. As a result, at least four structural alter­ natives will be considered for evaluation in the draft EIS, the scoping notice indicates.

800) 442-6916; email [email protected]; fax (307)266-0568. QUESTIONS AND ANSWERS Use this space to remind yourself of questions you wish GREYBULL VALLEY DAM AND to ask or to make notes on comments you wish to make. RESERVOIR PROJECT EIS PUBLIC SCOPING MEETING

I

EMBLEM GYM October 26, 1994 7:00 PM

Greybull Valley Dam and Reservoir Location Area

u.s. ARMY, CORPS OF ENGINEERS U.S. DEPARTMENT OF INTERIOR BUREAU OF LAND MANAGEMENT WELCOME! PUBLIC SCOPING MEETING AGENDA GREYBULL VALLEY DAM & RESERVOIR PROJECT EIS PUBLIC MEETING

The Greybull Valley Irrigation District is proposing construction of an off-channel dam and reservoir to increase Greybull River storage capacity and improve Welcome and Introductions ...... Rodney Schwartz, delivery reliability and conservation opportunities for area Army Corps of Engineers farm irrigation water. Approvals by the U.S. Army Corps Don Ogaard, of Engineers and the Bureau of Land Management are Bureau of Land Management necessary for the project to proceed as proposed. An environmental impact statement (EIS) is being prepared to assist them in their decisions. Project and Process Overviews ...... Dale Strickland and Dennis Earhart, This meeting provides you an opportunity to learn about West Consulting Team the proposal, the EIS process, and to help determine what issues should be addressed in considering the proposal. Your involvement is important in determining the scope of Small Group Discussions ...... Everyone environmental reviews. Small Group Reports ...... Group Spokespersons After presentations on the proposed project, potential alternatives, and the EIS process, we will break into small discussion groups to hear about issues you want Closing Remarks ...... Army Corps of Engineers addressed. In addition to participating tonight, you are Bureau of Land Management encouraged to submit written comments. Copies of the Scoping Notice and a comment sheet are available. You may leave your written comments at the registration table or mail them to the address below by November 9, 1994. THANK YOU FOR YOUR PARTICIPATION. Robert Nebel, Chief Environmental Analysis Branch, Planning Division U. S. Army, Corps of Engineers 215 North 17th Street Omaha, Nebraska 68102-4978 GREYBULL VALLEY IRRIGATION DISTRICT DAM AND RESERVOIR PROPOSAL

FACT SHEET

The Greybull Valley Irrigation District has proposed construction and operation of a dam and reservoir in Lo\ver Roach Gulch southwest of Burlington, Wyoming. The facility would store water from the Greybull River, but would be located outside of the river channel. The District's purposes are to increase the storage capacity for its Greybull River water rights, improve efficiency and timeliness of water delivery to District farms, and enhance opportunities for water conservation.

This Fact Sheet provides information on the District's proposal and issues/resource concerns which have been preliminarily identified for environmental analysis. A better understanding of what is proposed may be helpful to the public and interested agencies in suggesting other issues~ concerns, and! or potential alternatives to the proposal for consideration in the analysis and preparation of an Environmental Impact Statement.

Project Description

Reservoir Location: On public and private lands in the SWl/4,SW1I4 Section 23, T51N, R98W at the lower end of Roach Gulch, Park County, Wyoming at an elevation of 4,926 feet. Total land acquisition or use authorization necessary for the project is 200 acres private lands and 715 acres public lands administered by the Bureau of Land Management.

Dam Description: 150 feet high, 25 feet wide at its crest, and 1,700 feet long zoned-earth filled dam with a 150 foot wide earth channel spillway designed to handle 6,100 cubic feet per second and prevent a maximum potential flood condition overtopping of the dam.

Water Source: A small diversion dam in the Greybull River would divert \vater into a new 1,000 cubic feet per second (cfs) capacity, six-mile-long gravity flo\v supply canal \vhich \vould carry water to the ne\v reservoir. The diversion dam is proposed to allow minimum flo\v bypasses and fish passage.

Discharge Water: Water would be discharged from the dam outlet works to the Greybull River via aI, 100 foot long earth channel. The outlet would be a 60 inch steel conduit with two additional 50 inch diameter discharge pipes. Design capacity of the outlet works is 500 cfs.

Reservoir: At the Normal High Water Line, the proposed reservoir would store a total of 33,470 acre-feet and would inundate a total of 700 acres. There would be an estimated annual water yield of 26.500 acre-feet.

The Wyoming Game and Fish Department has determined in previous studies that the proposed reservoir would not provide a good fishery. Therefore, the minimum pool would be limited to 2,500 acre-feet.

Construction: If the proposal were approved, construction would probably begin within one year of agency decisions. Final design, final permitting, and actual construction may take three and a half years. Once completed, filling of the reservoir to full pool may take tvvo to three years depending upon runoff.

Crop acreage: All irrigated cropland in the Greybull River drainage, whether or not directly served by the reservoir, could potentially benefit from more reliable water supply through user agreements and water share purchases. The Greybull River Basin has a total of 88,000 acres permitted for irrigation and a total of 65,000 acres irrigated.

Preliminarily Identified Issues Among issues and sensitive resources preliminarily identified for analysis in an Environmental Impact Statement eElS) on this proposal are the following:

Land Features The general geological setting, geology and soils, and mineral resources.

Water Resources Stream flows and \vater supply needs, including an .analysis of the irrigated lands to be served by the proposed project. What are the supply needs for supplemental irrigation \vater for currently grown and irrigated crops? Flood Plains & Stream Channels Flood plains need to be evaluated for hydraulics, geomorphology, sedimentation, and fish habitat. Stream channel stability is of concern in relation to riparian vegetation and aquatic habitat.

Water Quality Potential effects to stream water quality.

Surface Water Determination of \vater supply need to serve all currently irrigated agricultural lands and the ability of the proposal or alternatives to meet those needs.

Ground Water Potential effects to ground water.

Water Rights

Verification and existing'- uses of water rights'-

Air Quality A baseline for area existing air quality needs to be established and an effects analysis conducted for non-agricultural lands and wilderness areas which could be impacted by construction/use activities

Noise Effects of construction/operation noise on humans and \vildlife within project vicinity

Biological Resources Wetland and Vegetation The nature and extent of wetland and vegetation potentially impacted; an assessment of quantity, quality, and wildlife value of affected wetland/riparian areas - both at construction sites and downstream. The loss of upland vegetation through construction or inundation and the effects of such loss.

Wildlife Wildlife \vithin the project area include big game, small game, furbearers, upland game birds, waterfowl, and nongame. The area is within yearlong mule deer and antelope range and includes white-tailed deer habitat.

Federally-listed threatened and endangered species potentially occurring within the area include bald eagle, peregrine falcon, and black-footed ferret. Candidate species potentially occurring \vithin the project area include ferruginous hawk, mountain plover, white-faced ibis, black tern, long-billed curlew, loggerhead shrike, and boreal toad.

Aquatic Species Potential negative or beneficial effects on existent cutthroat trout, mountain whitefish, and other area aquatic resources.

Cultural Resources The presence of archaeological resources including historic and prehistoric sites.

Recreational Resources Recreational opportunities and activity within the study area and potential project impacts.

Visual/Aesthetics Potential changes in the appearance of the landscape and the visuaVaesthetic human experience.

Socio-Economic Potential social and economics ramifications of implementation of the proposal, whether negative or beneficial.

Indirect and Cumulative Effects Indirect and cumulative effects by resource and/or issue including the combined effects of this project with other existing or proposed activities within the area.

The EIS will also consider the potential effects of alternatives to the project as proposed by the Greybull Valley Irrigation District. Among alternatives preliminarily being considered for EIS analysis are no action and three structural alternatives including off-channel sites at Blackstone Gulch and Rawhide Creek and an enlargement of the existing Upper Sunshine Reservoir. The final selection of alternatives for analysis "vill consider comments received during scoping.

Several Federal and state agencies have regulatory or policy interests in decisions on the proposal and in the EIS process. The U.S. Army Corps of Engineers and the Bureau of Land Management are co-leads for the EIS process. They have invited other interested agencies to participate as cooperating agencies.

Public and agency comments are invited on the proposal and issues which should be addressed by the EIS. Comments should be provided to the Corps of Engineers by November 9 at the follo,ving address: Robert Nebel, Chief; Environmental Analysis Branch, Planning Division; U.S. Army Corps of Engineers; 215 North 17th Street; Omaha, Nebraska 68102-4978. SCOPING NOTICE GREYBULL VALLEY DAM & RESERVOIR PROJECT

Greybull Valley Irrigation District Emblem, Wyoming September 15, 1994

The Greybull Valley Irrigation District is proposing construction of an off-channel dam and reservoir to increase Greybull River water storage capacity and supplement late season irrigation water for area farms in western Big Hom County, Wyoming. The attached map (Figure 2.1) displays the project area. Approvals by the u.S. Army Corps of Engineers and the Bureau of Land Management are necessary for the project to proceed as proposed.

These Federal agencies have determined that preparation of an environmental impact statement (EIS) is appropriate to assist them in their decisions. Public participation is invited and encouraged at the beginning of the process to identify issues and the scope of environmental analysis. Later, the public will be invited to comment on the analysis and findings as reported in a Draft EIS.

Scopine Meetin& A public scoping meeting for the Greybull Valley Dam and Reservoir Project EIS will be conducted October 26 in Emblem. All interested parties are encourage to participate. Information will be provided on the Greybull Valley Irrigation District proposal, potential alternatives to that proposal, and on the EIS purpose and process. The public will be asked to help identify issues which should be addressed in considering the proposal. The issues determined to be significant will shape the scope of environmental reviews and be applied in selecting reasonable alternatives for effects analysis.

Scoping Meeting: 7:00 p.m., October 26, 1994 Emblem Gym 3400 Road 10 Emblem, Wyoming

Written Comments Written comments are due November 9, 1994. Written comments or questions about the proposal should be provided to:

Robert Nebel, Chief (Telephone: 402-221-4598) Environmental Analysis Branch, Planning Division u.s. Army, Corps of Engineers 215 North 17th Street Omaha, Nebraska 68102-4978

1 Backeround The National Environmental Policy Act (NEPA) requires that decisions on any major federal action include consideration of reasonable alternatives and potential environmental effects. If implementation of a proposed action or its alternatives would include undesirable effects, incorporation of measures to mitigate those effects is also considered.

The major federal actions of this proposed project requiring NEPA compliance are the approval of a 404 permit for the project by the U.S. Army, Corps of Engineers (USACOE) and the approval of a Bureau of Land Management (BLM) right-of-way (ROW) application.

Current Action The Omaha District of the USACOE and the USDI BLM, Worland District, are preparing a Draft Environmental Impact Statement (DEIS) to evaluate the environmental impacts from the proposal to supply supplemental irrigation water to irrigated farm lands in the lower Greybull valley. The project has been named the Greybull Valley Dam and Reservoir Project.

Aeencies The USACOE, Omaha District and the USDI BLM, Worland District are acting as co-lead agencies in the NEP A process. A permit from the USACOE for discharging fill material into waters of the U.S. will be required to complete the project. A right-of-way application is required for constructing the reservoir on BLM lands.

The Greybull Valley Irrigation District (GVID) in conjunction with the Wyoming Water Development Commission (WWDC) are the sponsors of the project.

Additional state and federal agencies will be invited to participate in the process as cooperating agencies.

Purpose and Need for the Project The primary purpose of the Greybull Valley Dam and Reservoir Project is to provide supplemental water storage to the lower Greybull Valley Basin to reduce or prevent crop losses and failures and increase crop yields. It is estimated that approximately 30,000 acre-feet are needed to meet the current demands for supplemental irrigation water. Storage of water in the lower portion of the valley would allow more timely delivery of water to the majority of irrigated lands in the valley. The storage would conserve water by affording more efficient irrigation practices through greater control of the timing of water delivery.

2 Proposed Project Description The GVID is proposing to construct a ISO-foot-high zoned-earth embankment dam at a location at the lower end of Roach Gulch off of the Greybull River. The dam site is located primarily in the SWII4SW II4 of Section 23, T.Sl.N., R.98.W. on private land. The dam would be approximately 1,700 feet long with a 150-foot-wide earth channel spillway located on the left abutment. The reservoir created by this dam would hold approximately 30,000 acre-feet of water. A I,IOO-foot-Iong earth channel would discharge water from the outlet works back to the Greybull River. Water for filling the reservoir is proposed to be diverted from the Greybull River by a small diversion dam and carried to the reservoir via a new six-mile-long supply canal. The diversion dam would be designed to allow minimum flow bypasses and passage of fish.

Alternatives The WWDC has conducted a preliminary screening of a large number of alternatives to the proposed project. Alternatives included:

• a transbasin diversion project • enlarging the existing Sunshine reservoirs • other off-channel reservoir sites • main stem reservoir sites • developing groundwater • conservation • no action

A two-stage screening process was used to evaluate potential alternatives. Step one considered whether or not the alternative would meet the purpose and need for the project. The second step of the screening evaluated whether or not the projects would be financially feasible.

As a result of the initial screening of alternatives, at least four of the structural alternatives will be considered for detailed evaluation in the Draft Environmental Impact Statement. These four structural alternatives are all at off-channel sites. The number of alternatives may change depending on public involvement in the environmental analysis. Structural alternatives currently being considered for analysis in the DEIS include:

• Lower Roach Gulch Dam and Reservoir (GVID Proposal) • Blackstone Gulch Dam and Reservoir • Rawhide Dam and Reservoir • Upper Sunshine Reservoir Enlargement

Locations of the four structural alternatives and the other initially evaluated alternatives are displayed on the attached map, Figure 3.1.

3 Environmental Resources of Concern The NEP A process requires a thorough analysis of environmental concerns and issues and the possible effects on the environment from the proposed project and alternatives. Environmental analysis includes both the natural environment such as the earth resources and the man-made environment such as socioeconomics.

The Greybull Valley Dam and Reservoir Project DEIS will include analysis of potential effects to such resources as:

• earth resources • wetlands and water resources • wildlife and endangered species • cultural and historical resources • air resources • socioeconomics

Significant issues raised by the public during the scoping process will be addressed in the environmental analysis.

Public Involvement The public is given the opportunity to participate in the environmental analysis of the project in several ways. A scoping meeting is held to provide a forum for the public to express its concerns prior to the DEIS. Written comments are solicited from the public and may be provided via mail or at the scoping meeting. Following the publication of the DEIS, the public and interested parties will be provided 45 days to review the document and provide written comments. A public workshop and hearing will also be conducted during the comment period to afford the public opportunities to learn more about the environmental analysis and to provide oral comments. The Final EIS will respond to comments received on the draft document.

Public involvement is vital to assuring a thorough and responsive NEPA process. Any interested party is encouraged to participate.

Future Schedule Following review of comments received during scoping, data collection and analysis will begin for the DEIS. The Omaha District of the USACOE anticipates that the DEIS will be released for public review in June 1995. A Final EIS is anticipated to be completed in early 1996.

4 PARK BIG HORN COUNTY COUNTY

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