Fish/Shellfish Research and Management - Fish/Shellfish Research
Date Published: July 2004
Number of Pages: 137
Publication Number: DOE/BP-00006502-2
Author(s): Glen Mendel, Jeremy Trump, and Mike Gembala
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 sharp decline in discharge in late June, followed by low summer flows and then an increase in discharge in fall and winter. Manual stream flows at Pepper Rd bridge have shown substantial increases 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.
Stream temperatures in 2003 in the Walla Walla River were higher than those in 2002. Upper montane tributaries maintained maximum summer temperatures below 65EF, while sites in the middle and lower Touchet and Walla Walla rivers frequently had daily maximum temperatures well above 68EF (high enough to inhibit migration in adult and juvenile salmonids, and to sharply reduce survival of their embryos and fry). These high temperatures are possibly the most critical physiological barrier to salmonids in the Walla Walla basin, 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. The increased flows in the Walla Walla, due to the USFWS/Irrigation Districts settlement agreement, have not shown consistent improvements to stream temperatures.
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 bull trout in the Walla Walla River during snorkel surveys in June.
Due to high water conditions steelhead spawning surveys were limited in 2003. Surveyors found 9 redds on Mill Creek, 4 redds on Whiskey Creek, and 28 redds on the Coppei Creek system (7 on the South Fork Coppei, 14 on the North Fork Coppei, and 7 on the mainstem Coppei Creek). Bull trout spawning surveys in the upper Touchet River tributaries found a total of 126 redds and 149 live fish (101 redds and 79 fish in the Wolf Fork, 0 redds and 3 fish in the Burnt Fork, 0 redds and 0 fish in the South Fork Touchet, 25 redds and 67 fish in the North Fork Touchet, and 0 redds and 0 fish in Lewis Ck.). Bull trout redd surveys were summarized since 1990 for the Touchet River and Mill Creek. The Wolf Fork redds have increased the past few years but the NF has declined. No bull trout redds were found on the Burnt Fork for the first time since we began surveys in 2000.
Recommendations for assessment activities in 2004 included:
1) continue to monitor the Walla Walla River (focusing from the stateline to McDonald Rd., the Mill Ck system, and the Little Walla Walla System).
2) continue to reevaluate Whiskey Ck. for abundance and distribution of salmonids, and Lewis Ck. for bull trout density and distribution.
3) select or develop a habitat survey protocol and begin to conduct habitat inventory and assessment surveys. Implementation of habitat surveys is a very high priority as the lack of these data are significant data gaps for planning and habitat restoration actions.
4) begin to evaluate temperature and flow data to assess if the habitat conditions exist for spring chinook in the Touchet River.
Mendel, Glen, Jeremy Trump, Mike Gembala, "Assessment of Salmonids and their Habitat Conditions in the Walla Walla River Basin within Washington", 2003-2004 Annual Report, Project No. 199802000, 137 electronic pages, (BPA Report DOE/BP-00006502-2)
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