LOWER MONUMENTAL LOCK AND DAM--LAKE HERBERT G. WEST
(150 dpi) (75 dpi)

Snake River, Washington

CWIS: 10210

AUTHORIZATION: This project was authorized by the Flood Control Act of 1945 (Public Law 79-14), in accordance with House Document 704. Recreation was authorized in the Flood Control Act of 1944 (Public Law 78-534), as amended. Public Law 95-285, 95th Congress, approved May 25, 1978, designated the lake behind Lower Monumental Dam as "Lake Herbert G. West." Lower Monumental Lock and Dam is Unit 2 of 4 from the "Lower Snake River Project, Washington, and Idaho."

PROJECT: The project includes Lower Monumental Dam (photo), powerhouse, navigation lock, two fish ladders, and appurtenant facilities. The project provides navigation, hydroelectric generation, recreation, and incidental irrigation.

Lower Monumental Dam (150 dpi) (75 dpi): The dam is located at the head of Lake Sacajawea, the reservoir created by Ice Harbor Dam. It is 3,791 feet long, with an effective height of 100 feet. The dam is a concrete gravity-type dam, with short earthfill abutment embankments. The eight-bay spillway is 572 feet long, and has eight 50-foot by 60-foot tainter gates.

Lake Herbert G. West: The lake extends up the Snake River for a distance of 28.1 miles to the tailwater of Little Goose Dam. It has a surface area of 6,590 acres, and is at elevation 540.

Powerhouse: The powerhouse has six 135,000-kilowatt units. Power generated through September 1996 was 76.8 billion kilowatt hours.

Navigation Lock: The lock is a single-lift type, with a clear plan dimension of 86 feet by 666 feet and a 14-foot minimum depth.

Fish Passage: There are two fish ladders for passing migratory fish.

Lands: There are 8,335.5 acres of project lands surrounding Lake Herbert G. West. These project lands include fee lands that are Federally-owned and managed by the Corps, as well as easement lands to which the Corps has specific rights or easements (i.e., flowage or access). There are 7,024.0 acres of Corps- managed lands that are utilized for public recreation purposes, wildlife habitat, wildlife mitigation, and water-connected industrial development. At the present time, approximately 1177 acres are licensed to the State of Washington for Lyons Ferry State Park. Port districts own land both inside and adjacent to project lands for industrial development. Public boat-launching facilities are available at five locations along the shore line.

PROGRESS: Construction of the project began in June 1961, and the project became operational in 1969. The entire project is considered complete. Construction of the additional generating units started in 1975, and was completed in 1981.

COST: Total expenditures through September 1996 are $237,222,733 for new work (including $51,661,371 for power units 4 through 6) and $90,752,908 for operation and maintenance.

• Lower Monumental Lock and Dam West, Structural Details
  (150 dpi) (75 dpi)