Annual Report of the Chief of Engineers
on Civil Works Activities
Fiscal Year 1976
Department of the Army Corps of Engineers
Extract Report of Walla Walla District

Ririe Lake, Idaho

Location. On Willow Creek, a tributary of Snake River, in Bonneville County, Idaho. The channel improvement extends from junction of Sand and Willow Creeks to a point on Snake River about 4 miles upstream from city of Idaho Falls, Idaho. (See Geological Survey quadrangle map, Ucon, Idaho.) Dam is about 5 miles below confluence of Willow Creek and Meadow Creek and about 15 miles northeast of city of Idaho Falls, Idaho. (See Geological Survey quadrangle map, Poplar, Idaho.)

Existing project. See table 39-B for authorizing legislation. A rockfill dam about 840 feet long at the crest and about 184 feet high above streambed and downstream channel construction. Spillway has a concrete-lined channel in right abutment. Outlet works utilize a reinforced concrete conduit leading from an intake tower upstream to a stilling basin downstream at the toe of left abutment. Lake has gross storage capacity of 100,000 acre-feet; 90,000 acre-feet of active space for flood control, irrigation, and recreation; and 10,000 acre-feet of space for sediment storage and conservation. Floodway channel is about 8.0 miles long, with a capacity of 900 cubic feet per second. Authorization specified that the project shall be constructed by the Corps of Engineers and operated and maintained by the Water and Power Resources Service. Estimated Federal cost of new work (October 1976) is $38,230,000, including $30,000 for value of public-owned lands.

Local cooperation. Complete except for irrigation contracts.

Operations and results during fiscal year. A master plan was prepared by the Bureau of Reclamation and has been approved. Stream diversion began July 1973. A Project Transfer Agreement with the Bureau of Reclamation was signed on October 14, 1967 for transfer of the project for flood control and recreation use only until the irrigation water rights and space allocation issues are resolved. Project Fish & Wildlife Mitigation Agreement was completed by concerned agencies on 18 August 1976. Combination of a strike by the labor force, bad weather, and unanticipated poor foundation conditions has delayed project completion until FY 1978. Main dam construction is about 99 percent complete.

Condition as of September 30. Construction began June 1967. Approximately 98 percent of necessary real estate has been acquired. Entire project is about 90 percent complete. The final Environmental Impact Statement was filed with the Council on Environmental Quality February 13, 1973.