Wyoming State Water Plan - Snake/Salt River Basins: Issues

Snake River Basin

Current Issues:

In 1990 Wyoming entered into a contract with the U.S. Bureau of Reclamation (Bureau) for the purchase of 33,000 acre-feet of storage in Palisades Reservoir, a main stem storage facility located on the Snake River at the Wyoming-Idaho stateline. This amount was determined by calculating the replacement storage Wyoming is obligated to provide to Idaho if Wyoming fully develops its compact allocations. As Wyoming's current use is well below the total Compact allocation, Wyoming is using the storage water from Palisades in and below Jackson Lake Dam through an exchange procedure with the Bureau.

The contract called for an operating agreement between the State and the Bureau to define operations below Jackson Lake Dam. The native cutthroat trout fishery in the Snake River below Jackson Lake is important to the tourism-based economy in the area. Recreation in streams, rivers, lakes and reservoirs in the Basin represents a significant contribution to area development. During low water years, the Bureau has decreased winter releases from Jackson Lake to levels that are detrimental to the fishery. Wyoming plans to use storage water from Palisades, by exchanging it for use below Jackson Lake, to supplement the flows released by the Bureau during low water years.

The Corps of Engineers, through their Section 1135 authority, has reviewed the cumulative environmental effects of the flood control levees in the Jackson area. A plan to re-flood some areas on the upland side of the levees was developed, but Teton County felt their cost share portion under the Federal program was excessive. A scaled-back plan, which involves modifications to a headgate and abandoned gravel pits to regulate the water behind the levees, is proceeding.

The State Engineer's Office's West Bank Study, funded by the Water Development Commission, is completing an assessment of the groundwater-surface water interactions in the area between Teton Village and Wilson. As subdivisions continued to expand, new residents began to complain of excess water around their foundations and septic systems. The study is attempting to quantify the relationship between surface irrigation, river releases, and off-channel pond development in the area and resulting impacts to the housing areas.

Compact Allocations:

The Snake River Compact between Wyoming and Idaho was enacted into law in 1949. All permitted uses of water prior to June 30, 1949 were recognized. For future use, the flow of water at the Wyoming-Idaho state line is allocated 4% to Wyoming and 96% to Idaho. After the first 2% is put to beneficial use by Wyoming, replacement storage for one-third of the next 2% must be provided by Wyoming for Idaho use. When calculating these amounts based on the average state line flow, the storage replacement equals approximately 33,000 acre-feet. Wyoming believes its present use is well below the first 2%. A study underway at the Wyoming Water Resources Center is directed towards quantifying what additional consumptive uses have been established since 1949.

Future Concerns:

The changing demographics of the Jackson area have resulted in the conversion of irrigated hay fields to subdivisions and concentrated housing. Consumptive uses by these households will be less than the consumptive use from irrigated agriculture. Higher concentrations of people unfamiliar with the Western water law has increased the number of confrontations between homeowners and established water rights holders.

Wyoming is also concerned about Bureau delivery of water from the upper Snake River system to meet obligations in the salmon recovery efforts downstream in the Snake/Columbia River Basin. During dry years, these downstream deliveries are likely to impact carryover levels in Jackson Lake.

The Seven Basins of the Water Plan
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