Report of the Secretary of the Army
on Civil Works Activities for Fiscal Year 1997
Department of the Army Corps of Engineers
Extract Report of the Walla Walla District

Dworshak Dam and Reservoir, Idaho 

Dworshak National Fish Hatchery (DNFH):

Brood Year 1996 Steelhead. Approximately 2.49 million brood year (BY) 1996 steelhead smolts released in April/May 1997. This release was nearly 200,000 above the mitigation goal of 2.3 million. These smolts averaged 188 mm in total length, still under the 200 mm target size. Reduced size was due to cold water releases from Dworshak Dam in the summer. Because 1996 was a high water year, losses to Infectious Hematopoietic Necrosis Virus (IHNV) occurred in only two burrows ponds and four raceways. A total of 398,461 pounds of steelhead were released in 1997, compared with 392,845 poinds in 1996, and 332,000 pounds in 1995.

Brood Year 1997 Steelhead. A total of 2,980 adult steelhead returned to DNFH in the fall of 1996 and spring of 1997, compared with 4,480 the previous BY. A total of 2.88 million eggs went into the DNFH production program. The DNFH provided 805,100 eyed eggs to Clearwater Hatchery, and 1.5 million green eggs were air-shipped for rearing at the Magic Valley Hatchery. The Nez Perce Tribe (NPT) was provided 280,000 eyed eggs for their production program. No problems with IHNV were reported, the sixth year since 6,400 gpm water supply from the reservoir was installed. At the end of FY 97, 2.32 million brood year 97 steelhead were on hand at an average total length of 121 mm. The DNFH projected release for the spring of 1998 is 2.2 to 2.3 million steelhead smolts.

Brood Year 1995 Spring Chinook Salmon: The DNFH released 53,078 BY 95 spring chinook salmon on April 7 and 11, 1997. This was well below the 1.3 million target due to low numbers of returning adults (165 to DNFH and Kooskia NFH combined). Low egg survival (62 percent green-egg to smolt) contributed to the low release number. There were 4,187 pounds of BY 95 spring chinook released in FY 97.

Brood Year 1996 Spring Chinook Salmon: Adult returns in BY 96 included 963 fish to DNFH and 202 fish to Kooskia NFH. These adults produced approximately 1.1 million eyed eggs. At the end of FY 97, there were 787,000 BY 96 spring chinook fingerlings at DNFH averaging 103 mm in total length. With the addition of 195,000 Dworshak stock spring chinook fingerlings to be transferred from Kooskia NFH in the spring, the projected release from DNFH is 965,000 BY 96 spring chinook in 1998.

Brood Year 1997 Spring Chinook Salmon: Adult spring chinook returns to DNFH were the largest in recent history, with 3,150 adults returning to DNFH, and 1,657 returning to Kooskia NFH. After culling for Bacterial Kidney Disease, 2.3 million eyed eggs were being held at the two hatcheries for release in the spring of 1999.

Brood Year 1996 Coho Salmon: In a cooperative agreement with the NPT, DNFH is rearing 220,000 BY 96 coho salmon. The NPT is developing a Production Plan for the reintroduction of coho into the Clearwater Basin.

Brood Year 1995, 1996 Rainbow Trout: Approximately 6,000 BY 95 and 6,000 BY 96 rainbow trout were stocked into the settling pond at DNFH for Open House 97. The BY 95 trout were reared at DNFH, and the BY 96 trout were supplied by the Idaho Department of Fish and Game. The BY 95 trout were about 1 fish per pound and 15 inches in total length. Approximately 10,000 of these fish not caught during Open House were stocked into various Tribal waters after the Open House was over.

Brood Year 1996, 1997 Rainbow Trout: Due to concerns about disease (IHNV), the USFWS plans to rear 90,000 5-inch rainbow trout at Hagerman NFH to be stocked into L. Camas Reservoir, 20,000 9-inch trout to be stocked into Oxbow Reservoir, and 20,000 5-inch trout to be stocked into Hells Canyon Reservoir. In exchange, Idaho Department of Fish and Game will rear 30,000 10- to 12-inch rainbow trout to be stocked into Dworshak Reservoir in May.