Assessment of Salmonids and their habitat conditions in the Walla Walla River Basin within Washington: 2003 annual report
Mendel G, Trump J, Gembala M. 2004. Assessment of Salmonids and their habitat conditions in the Walla Walla River Basin within Washington: 2003 annual report. BPA Report DOE/BP-00006502-2. Bonneville Power Administration. Portland, Oregon
This study began in 1998 to assess salmonid distribution, relative abundance, genetics, and the condition of salmonid habitats in the Walla Walla River basin within Washington. Stream flows in the Walla Walla Basin continue to show a general trend that begins with a sharpdecline in discharge in late June, followed by low summer flows and then an increase indischarge in fall and winter. Manual stream flows at Pepper Rd bridge have shown substantialincreases in recent years. The increase is apparently associated with a 2000 settlement agreement between the U.S. Fish and Wildlife Service (USFWS) and the Irrigation Districts to leave minimum flows in the river. Rainbow/steelhead (Oncorhynchus mykiss) trout represent the most common salmonid in the basin. Densities of Rainbow/steelhead in the Walla Walla River from the Washington/Oregon stateline to Mojonnier Rd. increased from 2002, and are still considerably higher than before the USFWS settlement agreement. Other salmonids including; bull trout (Salvelinus confluentus), chinook salmon (Oncorhynchus tshawytscha), mountain whitefish (Prosopium williamsoni), and brown trout (Salmo trutta) had low densities, and limited distribution throughout the basin. Few spring chinook were documented in the Walla Walla basin in 2003. We failed to document bulltrout in the Walla Walla River during snorkel surveys in June.
- Type
- Published Report
- Authors
- Mendel, Glen; Trump, Jeremy; Gembala, Mike
- Date of Issue
- 2004-07
- Publisher
- Bonneville Power Administration
- Units
- UCBN , WHMI
- Keywords
- Bonneville Power Administration, habitat conditions, Observations, Presence (Biodiversity), Salmonids, US Department of Energy, Walla Walla River, Washington Department of Fish and Wildlife