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
