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.
