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

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 3,453,000 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. The 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 Fiscal Year 1990. 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 1995 price index) in potential flood damages. Power generation through September 1995 was 36.53 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 Big Eddy boat ramp and Dent Acres boat ramp extension. Initiated work on Freeman Creek ramp extension and water supply. During the fiscal year, 1.4 billion kw hours of electrical power were generated by the three generating units.

Dworshak National Fish Hatchery (DNFH): Just under 2.9 million steelhead smolts were released in the Spring of 1995. This release was above the mitigation goal of 2.3 million. These smolts from brood year 1994 averaged 187 mm in length, under the 200 mm target size due to cold water in the summer. The smolts were reared with a low number of losses to Infection Hemotopoietic Necrosis Virus (IHNV) or Ich. A total of 331,777 pounds of steelhead were produced this year compared to 280,377 pounds produced and released in 1994.

The steelhead production program (brood year 1995) at DNFH completed another early rearing phase in the hatchery's nursery without any problems with the IHNV. This is the fourth 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 brood year also made the transition to outside rearing ponds from water of the North Fork of the Clearwater River. The IHNV disease was a problem in recent years, but rearing the fish to a larger size and taking them to outside ponds later have reduced losses. A total of 6.76 million green eggs were produced from the 1,811 adult steelhead that returned to Dworshak and Kooskia National Fish Hatchery. Despite the low number of returning adults, the complex was able to ship 2,454,200 eyed eggs to the Clearwater and Magic Valley fish hatcheries.

The DNFH also released 1,311,445 spring chinook salmon weighing 93,422 pounds in the Spring of 1995. This is above the 75,386 pounds of spring chinook released in 1994; although fish numbers were quite close. The smolts released this year averaged 14.0 fish per pound, somewhat larger than the average smolt of earlier years. This was due to a decision to feed these fish close to manufacturer's recommended feeding rates rather than reduced feeding rates and compromise fish quality. Spring chinook adult returns to DNFH in 1995 produced only 124 fish, most of which were one-salt males. Only 51,250 eyed eggs resulted from these returning adults, or less than 4 percent of program goals.