LOWER GRANITE LOCK AND DAM--LOWER GRANITE LAKE
  Snake River, Washington
 

MAP: Site Plan (75 dpi) (150 dpi) | Dam Vicinity (75 dpi) (150 dpi) | Lewiston Levees (75 dpi) (150 dpi) | Levee Detail (75 dpi) (150 dpi)

CONDITION OF IMPROVEMENT: 30 September 2004

PWI NUMBER: 10180

AUTHORIZATION: The project was authorized by Section 2 of the River and Harbor Act of 1945 (Public Law 79-14), 79th Congress, 1st Session. It was approved March 2, 1945, in accordance with House Document 704, 75th Congress, 3d Session. Recreation was authorized in the River and Harbor Act of 1944 (Public Law 78-534, as amended. Lower Granite Lock and Dam is Unit 4 of 4 from the "Lower Snake River Project, Washington, and Idaho."

PROJECT: This project consists of Lower Granite Dam, powerhouse, navigation lock, two fish ladders, and appurtenant facilities. The project provides navigation, hydroelectric generation, recreation, and incidental irrigation.

Lower Granite Dam: The dam, located at the head of Lake Bryan, is about 3,200 feet long with an effective height of 100 feet. The dam is a concrete gravity type, with an earthfill right abutment embankment. It includes a navigation lock with clear dimensions of 86 by 674 feet; and an eight-bay spillway that is 512 feet long, with eight 50-foot by 60.5-foot radial gates.

Lower Granite Lake: The lake extends up the Snake River about 39.3 miles to Lewiston, Idaho, the upper terminus of the authorized Lower Snake River slack-water navigation project. It lies at elevation 738, and has a surface area of 8,900 acres.

Powerhouse: The powerhouse has six 135,000-kilowatt units. Power generated through September 1996 was 76.80 billion kilowatt hours.

Navigation Lock: The lock is a single-lift type, with a clear plan dimension of 86 feet by 674 feet and a 15-foot minimum depth.

Fish Passage: There is one fish ladder, with entrances on both shores, for passing migratory fish.

Levees: Backwater levees have been constructed around Lewiston, Idaho. Water surface at the dam varies between elevations 738 and 724 in order to maintain a normal operating range between elevations 738 and 733 in the Lewiston and Clarkston areas.

Lands: There are 5,777.6 acres of project lands surrounding Lower Granite Lake. 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 4,801.6 acres of Corps-managed lands that are utilized for public recreation purposes, wildlife habitat, wildlife mitigation, and water-connected industrial development. The Federal Government owns most of the acreage in fee title, while the remainder are easement lands. The project lands are utilized for public recreation purposes, wildlife habitat, wildlife mitigation, and water-connected industrial development. At the present time, approximately 515 acres are licensed either to State or local park agencies. Port districts own lands adjacent to the project for industrial development. Public boat launching facilities are available at 12 locations along the shore line.

PROGRESS: Construction began in July 1965, and was completed in 1984. The main dam is complete, as well as relocations and modifications to the Camas Prairie Railroad Bridge, state highways, and county roads. The installation of the first three power generating units is also complete. Construction is complete on the backwater levees in the Lewiston, Idaho area. A master plan was approved in 1974. Construction is complete on the recreational facilities along the lake shore. North shore embankment construction is complete. Power came online for additional units 4 through 6 in 1979. The entire project was completed in 1984. Final modifications to City of Lewiston's water intake were done in August 1987. A permanent trash shear boom has been installed.

As the first collector dam on the Snake River, Lower Granite is a primary component of the Juvenile Fish Transportation Program. The 2003 juvenile fish transport season was marked by slightly below average river flows. A new Removable Spillway Weir (RSW) was tested at Lower Granite Locka nd Dam, resulting in increased project passage via the spillway.

LOCAL COOPERATION: None required.

COST: Total expenditures through September 2006 were $624,098,663, including $400,080,315 for new work (including $46,212,534 for power units 4 through 6) and $224,018,348 for operation and maintenance. An additional $425,819 was contributed by local interests for the lock and dam.

PHOTOS:

REFERENCES:

Annual Report of the Secretary of the Army on Civil Works Activities for Fiscal Year 2004, Department oif the Army Corps of Engineers, Extract Report of the Walla Walla District.

Annual Report of the Secretary of the Army on Civil Works Activities, Fiscal Year 2003, Department of the Army Corps of Engineers, Extract Report of the Walla Walla District.

Lower Granite Master Plan, Design Memorandum No. 28. US Army Corps of Engineers, Walla Walla District, June 1974.