Concerns about
the decline of native salmon and trout populations have increased
among natural resource managers and the public in recent years. As
a result, a multitude of initiatives have been implemented at the
local, state, and federal government levels. These initiatives include
management plans and actions intended to protect and restore salmonid
fishes and their habitats.
In 1998 bull trout
were listed under the Endangered Species Act (ESA), as “Threatened”,
for the Walla Walla River and its tributaries. Steelhead were listed
as “Threatened” in 1999 for the mid–Columbia River
and its tributaries. These ESA listings emphasize the need for information
about the threatened salmonid populations and their habitats.
The Washington
Department of Fish and Wildlife (WDFW) is entrusted with “the
preservation, protection, and perpetuation of fish and wildlife....[and
to] maximize public recreational or commercial opportunities without
impairing the supply of fish and wildlife (WAC 77.12.010).”
In consideration of this mandate, the WDFW submitted a proposal in
December 1997 to the Bonneville Power Administration (BPA) for a study
to assess salmonid distribution, relative abundance, genetics, and
the condition of their habitats in the Walla Walla River basin.
The primary purposes
of this project are to collect baseline biological and habitat data,
to identify major data gaps, and to draw conclusions whenever possible.
The study reported herein details the findings of the 2000 field season
(March to November, 2000).
The Walla Walla
River and its major tributaries, including the Touchet River, comprise
a watershed of 1,758 square miles (ACOE 1997) and 2,454 major stream
miles (Knutson et al. 1992). The majority of the watershed (73%) lies
within Washington State, with the remainder in Oregon (Figure 1).
The Walla Walla River originates from a fine network of deeply incised
streams on the western slopes of the Blue Mountains. The Touchet River
originates from similar streams on the northwestern slopes of the
Blue Mountains, and also from seasonal streams draining Palouse hillsides
to the north. The Walla Walla River drains into the Columbia River
near Wallula Gap, about 21 miles above McNary Dam and 6 miles above
the Oregon border. The Touchet River drains into the Walla Walla River
just west of the town of Touchet, WA.
Historic and
contemporary land–use practices have had a profound impact on
the salmonid species abundance and distribution in the watershed.
Fish habitat in area streams has been severely degraded by urban and
agricultural development, grazing, tilling, logging, recreational
activities, and flood control structures. Agricultural diversions
have severely impacted stream flows in the Walla Walla River since
the 1880s (Nielson 1950). Nearly all (99%) of the surface water diversions
within Washington are for the purpose of irrigation (Pacific Groundwater
Group 1995). The reduced stream flows created by irrigation withdrawals
adversely impact salmonid survival within the basin. Additionally,
many unscreened or partly screened diversions and fish passage barriers
exist within the basin.
Out-of-basin impacts
to local fish populations have been substantial. Salmon migrating
to or from the ocean must pass through four dams and reservoirs on
the Columbia River before reaching their destination. Juvenile and
adult salmonid mortalities occur as they pass through each reservoir
or dam. Other impacts include over-harvest, habitat destruction in
the lower Columbia River and estuaries, predation, and industrial
pollution. Historically the basin probably produced substantial runs
of both spring chinook and summer steelhead. The last substantial
run of wild chinook took place in 1925; thereafter chinook populations
continued a precipitous decline, and the species is considered extirpated
in the basin (Nielson 1950, ACOE 1997). Anecdotal accounts and reports
of historic fisheries in adjacent basins, indicate that chum and coho
could have occurred in substantial numbers in the Walla Walla Basin
(Pirtle 1957), but little written documentation exists. Endemic steelhead
persist throughout much of the basin, but the population is considered
depressed (WDF and WDW 1993). Annually, approximately 200,000 non-endemic
hatchery steelhead (Lyons Ferry stock) are released in the middle
Touchet and lower Walla Walla rivers under the Lower Snake River Compensation
Program (LSRCP) to provide harvest mitigation for the four lower Snake
River dams.
Not all native
salmonids in the basin are anadromous. Whitefish, bull trout and rainbow/redband
trout exist within the basin. However, only rainbow/redband trout
retain a wide distribution. In the past, bull trout are thought to
have been widely distributed in the basin. Currently, bull trout distribution
is generally limited to montane upper tributaries of the Touchet River,
Walla Walla River, and Mill Creek (Mongillo 1993). However, bull trout
are known to migrate into the middle or lower reaches of these rivers
during the winter months. Many factors have led to the decline of
bull trout in southeast Washington. Damaged riparian vegetation, increased
sedimentation, and decreased water flows have resulted in elevated
water temperatures beyond the tolerance of this cold water species
(Mongillo,1993). Introduced rainbow trout or brown trout may have
increased competition or predation for bull trout.
Several non-native
fish species have been introduced to support recreational fishing,
or they have strayed into the basin. The Washington Department of
Game (now WDFW) began stocking brown trout (Salmo trutta) in the Touchet
River in the July, 1965. Stocking was discontinued in 1999 due to
concerns about competition, hybridization, and predation with native
bull trout, steelhead, or rainbow/redband trout. Carp were introduced
as early as 1884 (Walla Walla Daily Journal 1884). Channel catfish,
smallmouth bass, and bluegill are some of the warm water fish that
now occur in the lower basin. Additionally, in 1999, three-spine stickleback
(Gasterosteus aculeatus) were found in the Walla Walla river by WDFW
personnel involved with this project.
