Annual Report of the Chief of Engineers
on Civil Works Activities
Fiscal Year 1990
Department of the Army Corps of Engineers
Extract Report of Walla Walla District

Location. At River Mile 107.5 on Snake River at head of Lake Bryan (Little Goose Reservoir), and about 33 miles downstream from Lewiston, Idaho.

Existing project. The project includes a dam, powerplant, navigation lock, fish ladder, appurtenant facilities, and required about 8 miles of backwater levees along the Snake and Clearwater Rivers at Lewiston, Idaho. Project provides for slackwater navigation, hydroelectric power generation, recreation, and incidental irrigation. The reservoir has a normal operating range between Elevations 738 and 733 Mean Sea Level (MSL) in Lewiston, Idaho-Clarkston, Washington area. Lower Granite pool extends upstream about 38 miles, and provides slackwater to the confluence of the Snake and Clearwater Rivers. Dam structure is about 3,200 feet long and about 146 feet high above streambed. Fish passage facilities include one ladder with entrances on both shores with a fish channel through the spillway that connects to the powerhouse fish collection system and south shore ladder. Powerhouse has six 135,000 kilowatt generating units in operation for a capacity of 810,000 kilowatts. Spillway dam is 512 feet long and overflow crest at Elevation 581 MSL is surmounted by eight radial gates 60 feet wide and 60.5 feet high, which provide the capacity to pass a design flood of 850,000 cubic feet per second. Navigation lock is single-lift type, with clear plan dimensions of 86 by 675 feet and 15-foot minimum depth over the sills. A navigation channel 250 feet wide, 14 feet deep, and 38.0 miles long is provided from the dam to the confluence of the Snake and Clearwater Rivers. Principal data are set forth in table 39-J.

Construction of the original project started in July 1965 and was completed in 1984. Construction of the additional generating units was started in 1974 and completed in 1979. Power generation through September 1990 was 42.81 billion kilowatt hours. Approximately $4,119,300 in potential flood damages have been prevented since the levees became functional.

Local cooperation. None required.

Operations during fiscal year. Maintenance: Contracts continue for powerplant control. Operation and Maintenance: During fiscal year, 2.21 billion kilowatt hours of electrical power were generated by the six generating units. Traffic through the navigation lock consisted of grains, petroleum products, fertilizer, wood products, and miscellaneous cargo, and amounted to 2,131,516 tons during calendar year 1989.

As the first collection point on the Snake River, Lower Granite Dam is a primary component of the District's Juvenile Fish Transport Program. Transport began in the 1960's as a study of methods of bypassing juvenile steelhead and salmon around turbines of the Corps' Snake and Columbia River dams. Transport became a routine operation in 1980, while other structural modifications, installation of screens, and development of bypass systems continue.

For the transport program, the District has collection facilities at Lower Granite, Little Goose, and McNary Dams. Juvenile salmon and steelhead collected at these dams are hauled by specially-designed trucks or barges to release sites below Bonneville Dam. From there, they can travel unobstructed to the sea. In 1990, a record number of over 22,253,000 juvenile fish were collected, 9,352,000 at Lower Granite, 2,340,000 at Little Goose, and 10,561,000 at McNary Dam. Of these, 814,000 were bypassed at McNary Dam, and 21,439,000 were transported. With two new barges, transport capacities were reached during the peak of the outmigration at Lower Granite Dam, but no fish had to be returned to the river because of inadequate barge capacity as occurred in 1989. New collection facilities at Little Goose Dam functioned well. Work continued on upgrading and improving facilities with new sampling and office facilities under construction at Lower Granite Dam, a new collection/handling facility under construction at Lower Monumental Dam, and new collection or bypass facilities under design for McNary and Ice Harbor Dams. With added fish production from Clearwater Anadromous Fish Hatchery and Northwest Power Planning Council Fish and Wildlife Program restoration efforts, replacement trailers and additional barges will be required to keep the program functioning efficiently.