Assessment of Salmonids and Their Habitat Conditions in the Walla Walla River Basin within Washington: 2005 Annual Report

This study began in 1998 to assess salmonid distribution, relative abundance, genetic characteristics (stock status and trends), and the condition of salmonid habitats in the Walla Walla River Subbasin within Washington. Stream flows in the Walla Walla Subbasin continue to show a general trend that consists of a decline in discharge in late June, followed by low summer flows and then an increase in discharge in fall and winter.

Stream flows in the Walla Walla River have shown substantial increases in some areas 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 Walla Walla River.

Stream temperatures in 2005 in the Walla Walla Subbasin were similar to those in 2004. Upper montane tributaries maintained maximum summer temperatures below 65°F, while sites in the middle and lower Touchet and Walla Walla rivers frequently had daily maximum temperatures well above 68°F (high enough to inhibit migration in adult and juvenile salmonids, and to sharply reduce survival of their embryos and fry). High temperature is possibly the most critical physiological barrier to salmonids in the Walla Walla Subbasin, but other factors (available water, turbidity or sediment deposition, cover, lack of pools, etc.) also play a part in salmonid survival, migration, and breeding success. Increased flows in the Walla Walla River from the USFWS/Irrigation Districts settlement agreement, have not produced consistent improvements to stream temperatures.

Rainbow/steelhead trout (Oncorhynchus mykiss) represent the most common salmonid in the subbasin. Other salmonids including; bull trout (Salvelinus confluentus), chinook salmon (Oncorhynchus tshawytscha), and mountain whitefish (Prosopium williamsoni) had low densities and limited distribution throughout the subbasin.

Steelhead spawning surveys were conducted on four streams in the Walla Walla Subbasin in 2005. Surveyors found 80 redds on Mill Creek and 44 redds on the Coppei Creek system (22 on the South Fork Coppei, five on the North Fork Coppei, and 17 on the Mainstem Coppei Creek). Bull trout spawning surveys in the upper Touchet River tributaries found a total of 74 redds and 51 live fish (57 redds and 36 live fish in the Wolf Fork, 2 redds and 2 live fish in the Burnt Fork, and 15 redds and 13 live fish on the North Fork Touchet). Spring chinook spawning surveys were conducted in portions of the North Fork Touchet, Wolf Fork, and mainstem Touchet River in 2005, because five adults were observed at the adult trap in Dayton, plus redds were observed during bull trout spawning surveys. Surveyors found two redds and six live fish on the North Fork Touchet, 11 redds and seven fish (six live and one dead) on the Wolf Fork, and four redds and four fish (three live and one dead) on the Touchet River.

Recommendations for assessment activities in 2006 include:

1) summarize temperature and stream flow data from this project and what affects it has on salmonid migration.

2) continue to summarize steelhead spawning survey data

3) continue to monitor Mill Creek and Coppei Creek Watershed for steelhead spawning, and evaluate Yellowhawk Creek for steelhead spawning and summer rearing

4) continue bull trout spawning surveys in the upper Touchet River Watershed

5) summarize all data on whitefish in the Walla Walla Subbasin

6) complete genetic analysis and include results in the next annual report

7) develop joint BPA proposals with CTUIR and others for habitat and fish monitoring that will improve coordination and ensure collaborative, effective research, monitoring and evaluation (RM&E) within the subbasin.