This is a digital document from the collections of the Wyoming Water Resources Data System (WRDS) Library.

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1 This is a digital document from the collections of the Wyoming Water Resources Data System (WRDS) Library. For additional information about this document and the document conversion process, please contact WRDS at wrds@uwyo.edu and include the phrase Digital Documents in your subject heading. To view other documents please visit the WRDS Library online at: Mailing Address: Water Resources Data System University of Wyoming, Dept E University Avenue Laramie, WY Physical Address: Wyoming Hall, Room 249 University of Wyoming Laramie, WY Phone: (307) Fax: (307) Funding for WRDS and the creation of this electronic document was provided by the Wyoming Water Development Commission (

2 DONATED BY THE FAMILY IN~MORYOF FRANK 1. TRELEASE (1972) WYOMING'S SURFACE WATER SUPPLIES AN INFORMATION LEAFLET FROM THE WYOMING WATER PLANNING PROGRAM STATE ENGINEER'S OFFICE JUNE, 1972 Wyoming is the headwaters of the West. Streams flow from \\Tyoming in all directions to the major river systems of western United States. About 72 percent of the land area of Wyoming drains northward and eastward into the Missouri River system. Tributaries of the Colorado River drain about 17 percent of Wyoming. The Bear River meanders along the western Wyoming border and ends in Great Salt Lake in the Great Basin. The Snake River starts in Wyoming and joins the mighty Columbia River. These rivers drain about 7 percent of Wyoming's land area. The remaining 4 percent is in the Great Divide closed basin. Streams flow primarily as a result of runoff from precipitation. Annual precipitation in Wyoming varies from over 40 inches on some mountain areas to less than 6 inches in the desert basins. The largest volume of the annual runoff-approximately 70 percent-is snowmelt runoff during the months of April, May, June and July. The accompanying map shows the average annual streamflow in the principal rivers of ~ til o 0 ~ Wyoming. A summary of streamflow and water use data for ~Tyoming is given in Table I. ~ g ~ ~ Approximately 1.5 million acre-feet flow into Wyoming, and another 15.8 million acre-feet of ~ ~ ~ ~ water is produced within the State each year. Present water uses deplete streamflow about 2.6 g: ~ ~:r:: '[e million acre-feet per year, leaving 14.7 million acre-feet per year of water flowing from ~Tyoming ~ ~ P- ~ S into neighboring states. Irrigation is by far the largest consumptive use of water, averaging 2.1 ~ ~ ~ ~ M million acre-feet per year. Diversions of water considerably exceed the depletions from the water uses; thus, water is often used many times through the use of return flows. Surface water supplies are available for new uses from the 14.7 million acre-feet leaving the State annually. Water leaving the State also provides for fishing, recreation and hydropower generation while on its way. WATER RIGHTS The Wyoming Constitution declares that the waters of all natural streams, springs, lakes or other collections of still water within the boundaries of the State are the property of the State. Constitutional provisions allow the appropriation of water for beneficial uses, and establish the office of State Engineer and the Board of Control to supervise such appropriations. The Board of Control consists of the State Engineer (President) and the Superintendents of each of the four administrative water divisions of the State. The State Engineer has "general supervision of the waters of the State and of the officers connected with its distribution.'~

3 ,.,.,.. Major Drainage Basin,..., Sub-Basin Average Annual Streamflow

4 TABLE 1 - Wyoming Average Annual Streamflows and Water Uses Streamflow Base Period (Figures in Acre-Feet) River Basin & Streamflow Water State Line Man's Depletions of Streamflow in Wyoming Depleted Subdrainage Into Yield Outflow- Streamflow Wyoming Within Natural Irrigation Municipal Reservoir Total Leaving From Other Wyoming Conditions & Industrial Evaporation Wyoming States (1) (2) (3) (4)=(2)+(3) (5) (6) (7) (8) (9)=(4)-(8) Missouri River Basin Yellowstone River 299,000 2,407,000 2,706,000 2,706,000 Clarks Fork 147, , ,000 21,000 1,000 22, ,000 Big Horn River 3,673,000 3,673,000 1,007,000 5, ,000 1,117,000 2,556,000 Tongue River 385, ,300 77, ,000 82, ,000 Powder River 417, ,400 66, ,000 94, ,000 Little Missouri River 35,000 35,000 2,000 2,000 4,000 31,000 Belle Fourche River 96,000 96,000 2,000 1,000 17,000 20,000 76,000 Cheyenne River 85,400 85,400 4,000 2,400 14,000 20,400 65,000 Niobrara River 7,000 7,000 3,000 1,000 4,000 3,000 North Platte River 530,000 1,213,000 1,743, ,000 14, , , ,000 So. Platte River Basin 20,500 20,500 4,000 4,500 3,000 11,500 9,000 SUBTOTALS 976,000 8,904,600 9,880,600 1,760,000 27, ,000 2,139,600 7,741,000 Colorado River Basin Green River Basin 391,000 1,927,000 2,318, ,000 28,000 26, ,000 2,022,000 Great Basin Bear River 140, , ,500 61, ,000 68, ,000 Columbia River Basin Snake River Basin 4,722,200 4,722,200 84, ,000 89,200 4,633,000 TOTALS 1,507,000 15,827,300 17,334,300 2,147,000 56, ,000 2,593,300 14,741,000 1 acre-foot = 43,560 cubic feet, or the quantity to cover 1 acre 1 foot deep with water = 325,900 gallons. 1 cubic foot per second = 449 gallons per minute = 646,000 gallons per day = 1.98 acre-feet per day.

5 State statutes establish the procedure for the appropriation of water for beneficial use. First, a permit to use water must be obtained from the State Engineer. After the water has been put to use and proof of beneficial use is made to the Board of Control, the Board will adjudicate the water right. Priority of appropriation is based upon the relative date on which applications for permits were accepted in the State Engineer's Office. "First in time is first in right" is the basis of Wyoming water law. Although the Wyoming Constitution declares water to be the property of the State, as a practical matter Wyoming is limited in the amount that she can deplete the streamflows because of the water rights established in other states. INTERSTATE WATER RIGHTS The State's leaders realized many years ago that downstream states developing faster than Wyoming might establish prior water rights that could stifle future Wyoming development. Interstate stream compacts, which are agreements regarding the division of water among states, were negotiated on most of Wyoming's streams. The uses of water from two rivers, the North Platte and the Laramie, were litigated in the Supreme Court of the United States. A brief description of these interstate arrangements is required to indicate the amount of water actually available for new uses in Wyoming: Yellowstone River Compact MISSOURI RIVER BASIN The Yellowstone River Compact involves the States of Wyoming, Montana and North Dakota. It recognizes all water rights existing as of January 1, 1950, provides for a supplemental water supply for these pre-compact rights and allocates the remaining divertible flow of the interstate tributaries between Wyoming and Montana as follows: Clarks Fork - Wyoming's allocation is 60 percent of the unused and unappropriated flows of Clarks Fork of the Yellowstone River. Besides supplying supplemental water to pre-1950 water rights, about 429,000 acre-feet of water per year are available to Nyoming users. Big Horn River - Wyoming's allocation is 80 percent of the unused and unappropriated flows of the Big Horn River. Besides supplying supplemental water to pre-1950 water rights, about 1.8 million acre-feet of water per year are available for Wyoming consumptive uses. Tongue River - Wyoming's allocation is 40 percent of the unused and unappropriated flows of the Tongue River. Besides supplying supplemental water to pre-1950 water rights, about 96,000 acre-feet of water per year are available for Wyoming consumptive uses. Powder River - Wyoming's allocation is 42 percent of the unused and unappropriated flows of the Powder River. Besides supplying supplemental water to pre-1950 water rights, about 121,000 acre-feet of water per year are available for Wyoming consumptive uses. It is estimated that Wyoming can use another 494,000 acre-feet of water per year from the Yellowstone River tributaries for supplementing pre-1950 rights and for other uses with pre-1950 water rights. -4-

6 Belle Fourche River Compact This compact between Wyoming and South Dakota recognizes all existing water rights in the two states as of Under the compact, Wyoming is permitted unlimited use for stock water reservoirs with a capacity of 20 acre-feet or less, and Wyoming can deplete the flow under conditions existing as of 1943 by an additional 10 percent. It is estimated that about 7,000 acre-feet of water per year could be developed in Wyoming under the Belle Fourche River Compact. Cheyenne River No compact has been negotiated between Wyoming and South Dakota on the Cheyenne River. It is estimated, however, that an annual water supply of 15,000 acre-feet could be developed in Wyoming with storage on the Cheyenne River system. Upper Niobrara River Compact This compact essentially is a regulatory one that restricts the amount of water that can be stored in Wyoming. The compact recognizes that an allocation of groundwater may be necessary but groundwater provisions were not included because of inadequate information regarding the resource. North Platte River Decree During the drought of the 1930's, Nebraska brought suit in the U.S. Supreme Court against Wyoming and Colorado over administration of the waters of the North Platte River. The decree issued in 1945 restricts the State of Wyoming to the irrigation of not more than 168,000 acres of land, exclusive of the Kendrick Project, from the main stem of the North Platte River above Guernsey Reservoir and the tributaries of the North Platte River above Pathfinder Dam. Exclusive of Seminoe Reservoir, not more than 18,000 acre-feet of irrigation water may be stored in Wyoming on the North Platte River or its tributaries above Pathfinder Dam in anyone water year. In addition, the natural flow of the North Platte River below Guernsey Dam in Wyoming is allocated 25 percent to Wyoming and 75 percent to Nebraska. It is estimated that a water supply of b8,uuu acre-feet per year could be developed from North Platte River tributaries below Pathfinder Dam which are excluded from the terms of the decree. Laramie River Decree This U.S. Supreme Court decree limits diversions of water in Colorado from the Laramie River to adjacent lands and to the Cache La Poudre River. Wyoming instigated the court proceedings in 1911 to limit diversions from the already over appropriated river. Colorado River Basin Compacts COLORADO RIVER BASIN The Colorado River Compact of 1922 allocates consumptive uses of water in the Colorado River system between the Upper Basin States (Wyoming, Colorado, New Mexico and Utah) and the Lower Basin States (Arizona, Nevada and California). Among other provisions, the compact allocates the consumptive use of 7.5 million acre-feet of water per year to each of the Upper and Lower Basins. -5-

7 The Upper Colorado River Basin Compact divides the Upper Basin allocation among the Upper Basin states. Wyoming's allocation is 14 percent of the Upper Basin allocation and amounts to a consumptive use of 1,043,000 acre-feet of water per year, on the basis of 7.5 million acre-feet being available for use in the Upper Basin. The Colorado River, however, has not produced the amount of water estimated at the time the compacts were agreed upon. Recent hydrology studies show that unless the water supply increases to the compact estimates, the Upper Basin water supply will be less than 7.5 m.a.f. per year. Deducting Wyoming's present consumptive uses of 296,000 acre-feet per year from the 1,043,000 acre-foot allocation leaves 747,000 acre-feet per year available for new consumptive uses. If the water supply is not improved, however, Wyoming may be limited to the use of 579,000 acre-feet per year of additional consumptive uses. Bear River Compact GREAT BASIN A three-state compact on the Bear River provides for regulation of the interstate waters of the Bear River which meanders along the borders of Utah, Wyoming and Idaho. The amount of water that can be stored in Wyoming and Utah reservoirs is limited by the compact. Although some supplemental water supplies can be developed, the Bear River Compact essentially stops developments for new uses in Wyoming. The states involved are presently considering possible modifications to the compact. Snake River Compact COLUMBIA RIVER BASIN Wyoming and Idaho agreed on a compact recognizing all existing Wyoming water rights as of 1949 and permitting Wyoming unlimited use of stock water reservoirs with 20 acre-foot capacity or less. The compact permits Wyoming to divert for new developments, either for supplemental supply or original supply, 4 percent of the Wyoming-Idaho State-line flow of the Snake River. Under these terms, Wyoming can divert 160,000 acre-feet per year in addition to diversions under pre-1949 rights. WATER AVAILABLE FOR NEW USES Summing up the analysis of the interstate stream compacts and court decrees, future Wyoming water uses can increase streamflow depletions some 3.8 million acre-feet per year over present uses. However, existing water uses utilize the dependable flows of most streams, and surpluses are available primarily during the snowmelt runoff period of the year or during the winter months. Thus, water storage facilities are required in most instances to control the water surpluses and put them to use. Another factor that must be considered is the location of future water needs with respect to the location of water supplies. The large water surpluses are available only in select rivers and tributaries, and these surpluses may have to be diverted to the location of the water needs. -6-