The factors that limit resident fish populations in Latah County are primarily degraded water quality, extreme fluctuations in water quantity and degraded in-stream habitat conditions.
The limiting factors for steelhead within the Potlatch River include; high water temperatures , flashy stream flows, low summer base flows, lack of complexity in stream composition, barriers to migration, and sedimentation.
The Latah SWCD’s Potlatch River Watershed Management Plan delineates, by priority sub-watersheds within the Potlatch River watershed, best management practices to address the limiting factors within each sub-watershed.
The two principal steam systems within Latah county are the Palouse River and Potlatch River watersheds.
The eastern most part of the Palouse River Watershed is located in the western half of Latah county. The Palouse river flows through Whitman County in Washington and joins the Snake River approximately 50 miles east of the Tri-Cities, where the Snake flows into the Columbia River.
The Potlatch River Watershed is located primarily in the eastern half of Latah County. The Potlatch joins the Clearwater River South of Juliaetta near the junction of Highway 3 with US 12. The Clearwater joins the snake on the Washington-Idaho border in Lewiston.
As the Palouse River flows southwesterly into Washington State, it plunges over Palouse Falls near its confluence with the Snake River. The falls, at 182 feet tall, is a current and historical barrier for anadromous fish migration into Idaho.
The Potlatch River flows freely, with no significant natural or man-made impediments from its headwaters to its mouth, and does support anadromous fish migration into Latah County. Anadromous fish are those fish that spawn and rear in freshwater before migrating downstream to open ocean waters. The anadromous fish returns to its birthplace after reaching maturity in the ocean.
Steelhead are the significant anadromous fish in the Potlatch River; limited numbers of fall chinook and coho salmon are also found. Steelhead in the Potlatch River watershed are considered members of the Snake River steelhead group. Snake River steelhead are generally classified as summer run, based on their adult run timing patterns. Summer steelhead enter the Columbia River from late June to October. After holding over in the Columbia River through the winter, summer steelhead spawn during the following spring, usually from February through April. Unlike salmon, steelhead can return to the ocean after spawning and will return year after year to spawn where they hatched.
Fish Species of Latah County
Thirty-seven fish species have been documented within the Palouse subbasin, with at least 14 species in the Idaho portion of the watershed. All native species found within Idaho are non-game fish. No ESA listed species have been documented as occurring above Palouse Falls.
The Potlatch River and its tributaries support a cold water resident fishery which includes the common game species of rainbow and brook trout. Other fish species occurring in the Potlatch River include westslope cutthroat trout, largemouth and smallmouth bass, pumpkinseed, northern pikeminnow, chiselmouth, bridgelip sucker, yellow perch, speckled and longnose dace, redside shiners, sunfish, and sculpin.