Report of the Secretary of the Army
on Civil Works Activities for Fiscal Year 1996
Department of the Army Corps of Engineers
Extract Report of the Walla Walla District

Dworshak Dam and Reservoir, Idaho

Existing project. The project includes a dam, powerplant, and appurtenant facilities. Project provides for flood control, navigation, hydroelectric power generation, recreation, and area redevelopment. The reservoir has a normal operating range between the elevations of 1,600 and 1,445 mean sea level (msl). The reservoir has a gross storage capacity of 3,468,000 acre-feet (2 million acre-feet of which are effective for both local and regional flood control and for at-site and downstream power generation). In addition, the reservoir, extending 53 miles into rugged and relatively inaccessible timberland, provides important transportation savings in connection with movements of marketable logs. The reservoir is habitat for elk, deer, and other wildlife. The dam structure is about 3,300 feet long and about 717 feet above the streambed. Fish passage is not feasible due to the height of the dam. A hatchery has been built below the dam to assure continuance of anadromous fish runs. The Powerhouse has two 90,000 kilowatts (kw) and one 220,000 kw generating units in operation, for a capacity of 400,000 kw. Provisions had been made for three additional 220,000 kw generating units, for an ultimate installed capacity of 1,060,000 kw, and a reconnaissance report justifying the feasibility and cost benefits for the addition of a 200,000 kw fourth generating unit was completed in Fiscal Year 1978. However, environmental and economic studies on additional generating units have been curtailed due to public opposition. Unit 4 is undeveloped. Units 5 and 6 were deauthorized in Fiscal Year 1990. Unit 4 was deauthorized in Fiscal Year 1995. Principal project data are set forth in table 39-J.

Construction of the project started in July 1966, was placed in operation in 1972, and was completed in 1986. Since the project became operational in June 1972, it has prevented about $737,000 (adjusted to October 1996 price index) in potential flood damages. Power generation through September 1996 was 38.93 billion kw hours.

Eighty mini-recreation sites have been established along the reservoir shoreline. Each site includes at least a picnic table, U.S. Forest Service-type fireplace, and chemical toilet. Some of the sites have several picnic tables. Dent Acres and Freeman Creek recreation sites are open to the public. Facilities consist of a boat-launching ramp, boat docks, car-trailer parking, comfort stations, and fully-developed overnight camping.

Local cooperation. None required.

Operations during fiscal year. Operation and Maintenance: Development of wildlife habitat browse continued on project lands to provide winter browse for elk and deer. Completed work on Freeman Creek ramp extension and water supply. During the fiscal year, 2.4 billion kw hours of electrical power were generated by the three generating units.

Dworshak National Fish Hatchery (DNFH):

Brood Year 1995 Steelhead. There were 2.4 million steelhead smolts released in April/May 1996. This release was above the mitigation goal of 2.3 million. These smolts are from brood year 1995. They averaged 195 millimeters (mm) in total length, slightly under the 200 mm target size, due to cold water releases from Dworshak Dam in the summer. The smolts were reared with low numbers of losses to Infectious Hemotopoietic Necrosis Virus (IHNV), as only fish in nine ponds broke out with the virus. A total of 392,845 pounds of steelhead, as compared to 332,000 pounds in 1995 and 280,000 pounds in 1994.

Brood Year 1996 Steelhead. There were 4,480 steelhead returned to DNFH in Spring 1996. A total of 2.88 million eyed eggs went into Dworshak's production program. Dworshak shipped 145,000 eyed eggs and 782,000 green eggs to Clearwater Hatchery. Also, 1.69 million green eggs went to Magic Valley Hatchery. The production program at Dworshak completed another early rearing phase in the hatchery's nursery without any problems with IHNV. This is the fifth nursery rearing program that relied entirely on the water supply from Dworshak Reservoir. The 6,400 gallons per minute (gpm) received is sufficient to allow eggs and fry to be raised in reservoir water. The steelhead in this brook year also made the transition from inside rearing tanks to outside rearing ponds from water from the North Fork Clearwater River.

Brood Year 1994 Chinook Salmon. The DNFH released 102,903 spring chinook salmon, weighing 9,285 pounds, on April 11, 1996. This was below the 1.3 million target, mainly due to the low number of adult returns (306 to Dworshak and Kooskia, combined).

Brood Year 1995 Chinook Salmon. Adult returns of Brood Year 1995 produced only 165 fish to the combined stations. Only 51,250 eyed eggs resulted from these returning adults.

Brood Year 1996 Chinook Salmon. Adult returns of Brood Year 1996 produced 1,165 chinook to the combined stations. These have produced about 1.1 million eyed eggs.