Priest Lake Basin needs our protection

Priest Lake Basin needs our protection

The Lower Priest River needs our help. Thousands of people pass by the river on their way to Priest Lake. The 45-milelong section downstream from Priest Lake can be seen from the highway at a few spots, so most folks miss the splendor of this valuable natural resource and may not be aware of the threats to the river.

The Lower Priest River flows from Outlet Bay at Priest Lake. It is critical habitat for many species of wildlife, most especially native west slope cutthroat trout and bull trout. It is impaired and is at risk.

The Lower Priest River flowed freely from Priest Lake until a dam was constructed in 1950 downstream from where the river flows from Outlet Bay. This dam was replaced by a concrete gravity dam completed in 1978. The primary purpose of the dam is to maintain a lake level desirable for recreation in the summer months. The Outlet Dam does not generate electricity.

There is a misconception that Outlet Dam has had no influence on the Lower Priest River. Altering the flow has resulted in unintended problems for the river: decreased flows in late summer and increased water temperature of the water being released from the lake in late summer.

Decreased flows: During the months of August and September the storage of water in the lake to maintain the recreation level results in extremely low flows in the river below the lake. Prior to the construction of the Outlet Dam the mean minimum and average flows were higher volume in late summer when compared to after construction.

In the 34 years before Outlet Dam the August mean minimum was 242 cfs. After the dam (1951-1975) the August mean minimum was 102 cfs. September mean minimum before the dam was 174 cfs, after the dam 71 cfs. The August average flow before the dam was 508 cfs, after the dam 296 cfs. The September average before the dam was 337 cfs, after the dam 277 cfs. (Source: Priest River: Wild and Scenic Draft Environmental Statement and Study Report, USGS Water Supply Papers, Water Resources Data for Idaho) The average flows and the mean minimum flows significantly changed after installation of Outlet Dam, with negative impacts for the Lower Priest River in late summer. There are periods in late summer where the 60 cfs minimum isn’t being met because the mandated lake level has priority.

The recreation level of the lake does not change in late summer and remains at that level until October when water is released to obtain winter lake elevation. The recreation level has no flexibility, and the Lower Priest River becomes expendable.

Temperature: The Lower Priest River has been identified as temperature impaired, primarily in late summer. The location and operation of the Outlet Dam results in water pooling upstream of the dam, and as the release of water is slowed to maintain the recreation level of Priest Lake, the flow of water slows upstream of the dam. In the shallows the water is heated by the sun. There is no stratification of the temperature of the water. The temperature of the surface water is essentially the same as the water at the bottom of the river in this section. This warm water is released to the Lower Priest River.

The Outlet Dam is a tool that has been used for a primary purpose and it is time to use it as a multipurpose tool. Work started in 2020 to raise the height of Outlet Dam 6 inches to hold back additional water in the lake to be able to release water to the river in late summer, particularly during dry years. A step in the right direction to increase the volume being released in late summer but does nothing to address water temperature problem.

The momentum to restore and protect the Priest River is increasing and solutions are achievable.

The Priest River Project website ( is a repository of information about the Lower Priest River.Seven environment advocacy and outdoor groups have endorsed the work of the Priest River Project, advocating restoration backed by  science. Please explore the website and sign the petition to restore the river.

Trout Unlimited and partners are forming the Priest River Watershed Advisory Group. It will be working to coordinate efforts centered on improving water quality, quantity, and the overall condition of habitat in the Lower Priest River.

It is worth the effort to explore the Lower Priest River, become educated on the facts regarding the challenges, and support the restoration and enhancement of our valuable natural resource. Jon and Mary Quinn-Hurst built their first off grid cabin on the banks of the Priest River in 1980, and have been engaging in forest stewardship and efforts to protect the Priest River ever since. They continue to live on the same property north of Priest River, Idaho