Priest River Fisheries - FAQs

A: Yes. Summer water temperatures in the river downstream of Priest Lake consistently exceed the thermal limits for native coldwater fish, including westslope cutthroat trout, bull trout and mountain whitefish. This is the primary factor limiting survival of these species and results in low fish population densities. The river is designated as water quality impaired for temperature under Section 303(d) of the Clean Water Act because of the negative impacts of temperature on aquatic life.

A: This occurs because the river is fed by warm surface water leaving Priest Lake. Conditions likely worsened after construction of the Outlet Dam in the 1950s. Impoundment by the dam increased lake surface area and changed outflow dynamics through the outlet, which likely produces warmer outflow temperatures than before the dam was built. Additionally, warming climate trends have contributed to even higher water temperatures, and climate modeling predicts this will continue in the future.

A: Yes. A variety of land use activities (i.e., historical log drives, floodplain development, dam construction) have altered natural habitat conditions in the Priest River. However, these issues are far less problematic than warm summer water temperatures. If summer water temperatures were cooler, the Priest River could support much higher trout densities even without improving other habitat conditions. Other northern Idaho rivers, such as the North Fork Coeur d’Alene and St. Joe rivers, have similar habitat conditions to Priest River yet support much stronger trout populations because their summer water temperatures are cooler.

A: The Priest River still supports native coldwater fish populations, including westslope cutthroat trout, bull trout and mountain whitefish. Some non-native brown trout and rainbow trout are also present. Most of these coldwater fish only occupy the river seasonally and must migrate into tributaries or Lake Pend Oreille to find cooler water during the summer. Fish do not have access to Priest Lake in the summer because of the Outlet Dam. Warm summer river temperatures regulate trout densities at much lower levels than other similar-sized rivers in the region.  Priest River has been considered an under-performing coldwater fishery since the mid-1900s. The river provides some good fishing seasonally, but overall is a fairly poor fishery with low angler use.  Some non-native fish more tolerant of warm water temperatures are now established, most notably smallmouth bass, but catch rates are low for these species in most of the river.

A: Yes. Historically, the Priest River supported stronger populations of native coldwater fish. The river was an important and productive fishing ground for the Kalispel Tribe of Indians prior to white settlement. Even after many land use disturbances in the 19th and 20th centuries, oral history suggests the river provided much better fishing until the mid-1900s. Even historically, fish had to contend with warm summer water temperatures because surface outflow from Priest Lake has always fed the river. However, river temperatures were less extreme than they are now, and fish had better access to areas of thermal refuge.

A: A source of cold water to feed the river is needed during the summer months to lower water temperatures. Instream habitat restoration and enhancement is not sufficient because it cannot make the outflow from Priest Lake colder. Over the past decade, Idaho Fish and Game and the Kalispel Tribe have been evaluating the feasibility of a coldwater bypass concept that involves replacing a portion of the warm surface outflow from Priest Lake with colder water from deeper in the lake. Studies have shown this is a viable concept.