Annual Report of the Chief of Engineers
on Civil Works Activities
Fiscal Year 1988
Department of the Army Corps of Engineers
Extract Report of Walla Walla District
Lower Monumental Lock and Dam - Lake Herbert G. West, Washington
Location. On Snake River at head of Lake Sacajawea (Ice Harbor Reservoir), about 45 miles northeast of Pasco, Washington, and 41.6 miles above the river mouth.
Existing project. The project includes a dam, powerplant, fish ladders, navigation lock, appurtenant facilities, and relocated railroads and highways. The project functions include navigation, hydroelectric power generation, recreation, and incidental irrigation. The reservoir has a normal operating range between Elevations 540 and 537. The lake extends upstream about 28.7 miles to Little Goose Lock and Dam. The dam is concrete-gravity type, with earthfill and rockfill abutments. It is 3,800 feet long including abutments, spillway, navigation lock, and powerhouse; and is about 135 feet high above streambed. There are two fish ladders, one at each end of the dam. Powerhouse has six 135,000-kilowatt generating units, for a capacity of 810,000 kilowatts. Spillway dam is 508 feet long and overflow crest at Elevation 483 MSL is surmounted by 8 radial gates, 50 feet wide and 61 feet high. Deck is at elevation 553 MSL, and provides a service road and track for a gantry crane. Navigation lock is single-lift type with lock chamber 86 by 675 and minimum depth of 15 feet over the sills. Principal data are set forth in table 39-J.
Construction began June 1961, and the project was open to navigation April 1969. The project is complete.
A final Environmental Impact Statement was filed with the Council on Environmental Quality on May 21, 1976.
Power generation through September 1988 has been 50.87 billion kilowatt hours.
Local cooperation. None required.
Operations during fiscal year. Maintenance: Normal operation and maintenance continued. Contracts continued for generator thrust bearing repair, powerplant control, and Unit 2 repair. Cargoes totaling 3,258,560 tons passed through the navigation lock during calendar year 1987.