Fish Passage Center 2007 Annual Report.
- Fish Passage Center of the Columbia Basin Fish & Wildlife Authority
The January-July runoff volume above the Dalles Dam in 2007 was 89% of the average runoff volume for the 1971-2000 historical record. The April-July runoff volume at Lower Granite Dam was 68% of the 1971-2000 historical record. Over the 79 year historical record from 1929 through 2007, the 2007 January-July runoff volume at the Dalles was the 50th lowest year out of the 79th year record. The January through July runoff volume at Lower Granite was the 65th lowest runoff year out of 79 on record. This year can be characterized by steadily decreasing snowpack which was below average in the Columbia Basin by the end of April. The combination of runoff volume, decreasing snowpack and reservoir operations resulted in spring migration flows at McNary Dam averaging 239 Kcfs, slightly above the Biological Opinion flow objective of 237 Kcfs. However the spring period migration flows in the Snake River averaged 61 Kcfs at Lower Granite Dam, substantially below the Biological Opinion flow objective of 85 Kcfs. Summer migration period Biological Opinion flow objectives averaged 163 Kcfs at McNary Dam, substantially below the summer flow objective of 200 Kcfs. Summer migration period flows in the Snake River at Lower Granite Dam averaged 29 Kcfs, also substantially below the Biological Opinion flow objective of 50 Kcfs. Overall spring migrants in the Columbia River experienced better migration flows than spring migrants in the Snake River reach. Summer migration flow objectives were not achieved in either the Columbia or Snake rivers. The 2007 FCRPS Operations Agreement represents an expanded and improved spill program that goes beyond the measures contained in the 2004 Biological Opinion. During the spring period, spill now occurs for twenty-four hours per day at all projects, except for John Day Dam where the daily program remains at 12 hours. A summer spill program provides spill at all the fish transportation collector projects (Lower Granite, Little Goose, Lower Monumental and McNary dams), whereas prior to 2005 spill was terminated at these projects after the spring period. In addition, the 2007 operations agreement provided regardless of flow conditions. For the first time spill for fish passage was provided in the low flow conditions that prevailed in the Snake River throughout the spring and summer migration periods. Gas bubble trauma (GBT) monitoring continued throughout the spill period. A higher incidence of rank 1, GBT signs were observed in late arriving steelhead smolts arriving after the 95% passage date had occurred. During this time dissolved gas levels were generally below the 110% water quality standard in the forebay where fish were sampled. This occurrence was due to prolonged exposure and extended travel times due to low migration flows. The 2007 migration conditions differed from any year in the historic record. The migration conditions combined low river flows in the Snake River with spill throughout the spring and summer season. The juvenile migration characteristics observed in 2007 were unique compared to past years in that high levels of 24 hour spill for fish passage were provided in low flow conditions, and with a delayed start to the smolt transportation program a smaller proportion of the total run being transported. This resulted in relatively high spring juvenile survival despite the lower flows. The seasonal spring average flow in the Snake River was 61 Kcfs much lower than the spring time average of 120 Kcfs that occurred in 2006. However juvenile steelhead survival through the Lower Granite to McNary reach in 2007 was nearly 70% which was similar to the juvenile steelhead survival seen in 2006 under higher migration flows. The low flows in the May-July period of 2007 were similar to the 2001 low flow year, yet survival for fall chinook juveniles in this period in 2007 was much higher. In 2001 the reach survival estimate for juvenile fall Chinook from Lower Granite to McNary Dam ranged from 0.25-0.34, while survival in the same reach ranged between 0.54-0.60 in 2007. In addition travel time estimates showed that summer migrants traveled much more rapidly in 2007 than in 2001, even under similar flows. The median travel time through the Lower Granite to McNary reach for summer migrants averaged 22 days compared to a range of 32 to 42 days in 2001. The primary operational difference between 2001 and 2007 low flow years was the provision of 24 hour spill in 2007. Hatchery production of summer steelhead, fall chinook and coho increased in 2007 compared to 2006. However, hatchery production of fall chinook decreased in the Snake River zone in 2006. Coho production is still lower than the peak production level which occurred in 2004. Although hatchery steelhead releases increased in the Lower Columbia zone, the Snake River zone accounts for over 80% of the steelhead production in the Columbia Basin above Bonneville Dam.
- Research Organization:
- Bonneville Power Administration (BPA), Portland, OR (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- 35850
- OSTI ID:
- 962635
- Report Number(s):
- P109177; R&D Project: 1994-033-00; TRN: US200917%%56
- Country of Publication:
- United States
- Language:
- English
Similar Records
Fish Passage Center; Columbia Basin Fish and Wildlife Authority, 2003 Annual Report.
Fish Passage Center; Columbia Basin Fish and Wildlife Authority, 2002 Annual Report.