General

The principal features of the project are Palisades Dam Reservoir, and Powerplant. Palisades Dam is on the South Fork of the Snake River at Calamity Point in eastern Idaho about 11 miles west of the Idaho-Wyoming boundary. The project provides a supplemental water supply to about 650,000 acres of irrigated land in the Minidoka and Michaud Flats Projects. The 176,600 kilowatt hydroelectric powerplant furnishes energy needed in the upper valley to serve irrigation pumping units, municipalities, rural cooperatives, and other power users. The principal features of the project are Palisades Dam, Reservoir, and Powerplant.

Construction

The preconstruction phase of the project was started early in 1945. Construction was delayed until the close of World War II and until local interests gave satisfactory assurance to the Bureau of Reclamation that they would agree to important practices in the efficient water use of the entire Upper Snake River Basin through the workings of winter water savings and exchange agreements that were entered into by some 57 water entities as a part of the Palisades Project. Actual construction of the project was initiated in 1951 and completed in 1957. All generating units of the powerplant were in operation by May 1958.

Benefits

Irrigation
Palisades Dam provides holdover storage during years of average or above average precipitation for release in subsequent dry years to lands of the Upper Snake River Valley, the area served by diversions from the river above Milner Dam. This holdover storage assures an adequate supply of supplemental water for about 650,000 acres of irrigated lands in the valley. Principal crops are grain, alfalfa, pasture, dry beans, potatoes, sugar beets, other vegetables, and seeds.

In 1994, the United States entered into a contract with Mitigation, Inc., which provided that entity with the remaining non-contracted irrigation storage space in Palisades (18,980 acre-feet) andthe joint use capacity of Ririe (80,500 acre-feet) Reservoirs in order to mitigate the effects of implementation of the 1990 Fort Hall Indian Water Rights Agreement and Fort Hall Indian Rights Act of 1990. (104 Stat. 3061, Public Law 101-602) on exisiting non-Indian water users.

Recreation, Fish & Wildlife
Palisades Reservoir is in a scenic river valley with forested hillsides rising from the water to the towering snowcapped mountains which form the background. Since the reservoir is paralleled by U.S. Highway 26, much of the recreational use is by tourists. The reservoir has about 70 miles of shoreline and six access roads have been built. Recreation at Palisades Reservoir is administered by the Targhee National Forest headquartered in St. Anthony, Idaho. Public use facilities include six campgrounds, five picnic areas, and six boat ramps. Two boat clubs have facilities on the reservoir and private cabins have been constructed under lease from the Forest Service. The Bureau of Reclamation has developed a day-use area and campground below the dam to provide fishing and a boat launch on the Snake River.

In 1991, the State of Wyoming entered into a contract with the Bureau of Reclamation for the purchase of 33,000 acre-feet of `joint use` space in Palisades Reservoir. All Palisades Reservoir spaceholder contracts provide for use of a proportionate share of the water accruing to the Palisades Reservoir water rights, the ability to keep unused stored water for use in subsequent years, and the option of participating in the Water District 1 Rental Pool. Additionally, Wyoming has the option of making exchanges to allow the use of their Palisades Reservoir space to retain water in Jackson Lake or to increase winter flows in the Snake River to benefit cutthroat trout. The Palisades Reservoir space also insures Wyoming's ability to fulfill Snake River Compact obligations.

Hydroelectric Power
The Palisades Powerplant serves large irrigation pumping power requirements on and near the Minidoka Project in southern Idaho. Power not needed for Bureau of Reclamation project purposes is marketed in the Federal Southern Idaho Power System administered by the Bonneville Power Administration.

Flood Control
The project also provides substantial flood control benefits. The Palisades Project is a "section 7" project under provisions of the Flood Control Act of 1944 (33 CFR 208). A Flood Control Storage Reservation Diagram approved by the Corps and Reclamation, approved in 1958 is the basis for flood control operations. Space is reserved based on forecasts, coordinated by Reclamation and the Corps, and the Reservation Diagram. Space is reserved in Jackson Lake and Palisades Reservoir to reduce the flow of the Snake River near Heise, about 48 miles below Palisades Dam to 20,000 cubic feet per second, when possible.

Endangered Species Act
The Pacific Northwest Region consults with the NOAA Fisheries and the US Fish and Wildlife Service to ensure that project operations and other activities do not jeopardize ESA-listed species or their critical habitats. Fish and Wildlife Service (FWS) and National Marine Fisheries Service (NMFS) provided Biological Opinions on Reclamation's Operations and Maintenance of 12 projects and associated facilties in the Snake River Basin above Lower Brownlee Reservoir. The Palisades Project is one of the 12 projects covered in the Opinions.

If conditions don't change these Opinions should be valid through 2035.

For more information on ESA related activies please go to: https://www.usbr.gov/pn/programs/esa/index.html

For more information on the fish and wildlife program, please go to: https://www.usbr.gov/pn/programs/fishwild/index.html

Plan

The project, in addition to providing needed holdover storage, helps control floods, develops a substantial block of power, and permits the annual storage of about 135,000 acre-feet of water saved by shutting off canals in the upper valley during the winter. This water is stored to the credit of and delivered to the water users who make the savings possible.

Releases from Palisades Reservoir are diverted and carried to the land by previously constructed facilities.

Facility Descriptions

Palisades Dam
Located on the Snake River about 55 miles southeast of Idaho Falls, Idaho, Palisades Dam is a large zoned earthfill structure 270 feet high, has a crest length of 2,100 feet, and contains 13,571,000 cubic yards of material. At the time of construction, this was the largest volume of material placed in a dam by the Bureau of Reclamation. The spillway is a 28-foot-diameter tunnel through the left abutment, with a capacity of 48,500 cubic feet per second. The outlet works and power inlet structures are controlled by a fixed-wheel gate at the entrances of the inclined shafts leading to 26-foot-diameter tunnels. The outlet tunnel conveys the water to the steel manifold transition section, where it is released to the stilling basin by regulating gates. At the lower end of the power tunnel, the water may be released to the stilling basin or to four penstocks and conveyed to the turbines for power generation. The capacity of the outlet works is 33,000 cubic feet per second. The dam creates a reservoir of 1,401,000 acre-feet capacity (active 1,200,000 acre-feet).

The powerplant is on the downstream toe of the dam on the west side of the river and initially had a total capacity of 118,750 kilowatts. The powerplant was uprated in 1994  by rewinding the units increasing the nameplate capacity to a total of 176,600 kilowatts; 44,150 kilowatts each. As part of the mitigation for the powerplant uprate, a fish screen was constructed on Palisades Creek, a small tributary which joins the Snake River approximately 3 miles downstream from the dam.

Operating Agencies
The Bureau of Reclamation operates and maintains the project.

Other

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Overview

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History

Investigations
Following the drought period of the early 1930`s, a need was recognized for additional storage for lands already under irrigation in the Minidoka Project and in private developments, and investigations of various reservoir sites were made upstream from American Falls Dam. The Palisades site was selected for the construction of the dam and reservoir to provide holdover storage to supplement the water supply for existing irrigated lands, to develop a limited acreage of new lands, to provide flood control, and to generate electrical power. Intensive investigations at the location as now developed were started by the Bureau of Reclamation in 1934.

Authorization
The project was initially authorized by the Secretary of the Interior on December 9, 1941, under the provisions of Section 9 of the Reclamation Project Act of August 4,1939 (53 Stat. 1187, Public Law 76-260). Reauthorization of the project by the Congress occurred on September 30, 1950 (64 Stat. 1083, Public Law 81- 864), substantially in accordance with a supplemental report approved by the Secretary of the Interior on July 1, 1949.

The authorized purposes of the Palisades Project are irrigation, power, flood control, and fish and wildlife.