Report of the Secretary of the Army
on Civil Works Activities for Fiscal Year 1995
Department of the Army Corps of Engineers
Extract Report of the Walla Walla District

Lower Granite Lock and Dam, Washington

Existing project. The project includes a dam, powerplant, navigation lock, fish ladder, appurtenant facilities, and required about 8 miles of slackwater levees along the Snake and Clearwater Rivers at Lewiston, ID. The project provides for slackwater navigation, hydroelectric power generation, recreation, and incidental irrigation. The reservoir has a normal operating range between elevations 738 and 733 msl in Lewiston, ID, and Clarkston, WA. Lower Granite pool extends upstream about 38 miles and provides slackwater to the confluence of the Snake and Clearwater Rivers. The dam structure is about 3,200 feet long and about 146 feet above the streambed. Fish passage facilities include one ladder with entrances on both shores with a fish channel through the spillway which connects to the powerhouse fish collection system and south shore ladder. The powerhouse has six 135,000 kw generating units in operation for a capacity of 810,000 kw. Spillway dam is 512 feet long and the 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 cfs. 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 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, was placed in operation in 1975, and completed in 1984. Construction of additional generating units was started in 1974 and completed in 1979. Power generation through September 1995 was 51.39 billion kw hours. Approximately $4,622,000 (adjusted to October 1995 price index) in potential flood damage has been prevented since the levees became functional.

Local cooperation. None required.

Operations during fiscal year. Maintenance: Contract initiated for fish-trap repair. Contract completed for powerhouse roof repair. Contract awarded for repair of Lewiston Water Intake. Operation and Maintenance: During the fiscal year, 2.9 billion kw 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 2,313,586 tons during calendar year 1994.

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

The 1995 Transport Season was marked by improved river flows compared to drought conditions that have prevailed in the Columbia and Snake Rivers for most years since 1987. River flows in 1995 were equivalent to the 30-year average. Collection totaled 9,733,497 fish at Lower Granite compared to 6,911,174 fish in 1994 and 8,025,621 fish in 1993. Daily collection peaked at a new record level of 910,051 fish on May 3 compared to a peak of 507,700 fish in 1994 and the previous project daily collection record of 893,100 fish in 1993. High fish numbers several days in a row resulted in over 518,000 fish being released back to the river due to exceeding barge and raceway carrying capacity. A yearly total of 668,602 fish were bypassed for this reason and various research projects. At Little Goose Dam 3,070,040 juvenile salmon and steelhead were collected, a new seasonal record, up from the 1,513,538 fish collected in 1993. Approximately 660,000 fish were bypassed at Little Goose in 1995 as a result of lack of barge space and for various research projects. Lower Monumental Dam collected 2,734,298 juvenile salmon and steelhead, an increase from the 1,634,864 fish collected in 1994 and 1,337,339 fish collected 1993. A total of 1,073,869 fish were bypassed due to lack of barging space and for various research projects. At McNary Dam, 9,018,555 juvenile fish were collected, a slight increase from the 8,750,448 fish collected in 1994. Peak collection was 147,800 on May 18 when yearling fish dominated collection, and 617,100 on July 4 when subyearling fish comprised 99.9 percent of the collection. Juvenile fish collected during the spring were bypassed in compliance with National Marine Fisheries Service's biological opinion for endangered species act consultation. Transportation began in late June when subyearling chinook salmon predominated the collection. A total of 3,517,529 juvenile fish were bypassed for this reason and for various research projects. A grand total of 24,556,390 fish were collected in 1995, a new transportation program collection record, exceeding the previous record total of 22,261,661 collected in 1990. A total of 18,579,398 juvenile fish were transported, 75.6 percent of those collected. Of those transported 700,470 (3.7 percent) were by truck and 17,878,928 (96.3 percent) were by barge.