The Priest Lake Water Management Study was initiated by the IWRB to evaluate opportunities for improving operation of the Priest Lake (also known as Lower Priest Lake) and Priest River system. The study includes several action items.
Evaluation of alternatives for maintaining required recreational lake levels and maintaining current minimum discharge requirements downstream of the Priest Lake Outlet Dam (60 cfs).
Assessing potential structural and operational modifications to the dam.
Analyzing options to improve access and navigable conditions for the Priest Lake Thorofare.
Preserving lake levels through the main recreation season. This goal supports the local economy and meets current lake level requirements. It also avoids any negative impacts to downstream river flows.
Maintaining vessel access through the Thorofare channel between Upper Priest Lake and Priest Lake.
Project Study Area Description
Priest Lake is approximately 18 miles long, has a maximum depth greater than 300 feet, and has an active storage capacity of approximately 76,000 acre-feet. It is connected to Upper Priest Lake (which is approximately 3.3 miles long) by a three-mile long channel known as the "Thorofare," which has long been used by the public for recreation and access to the upper lake. A 1,400-foot-long timber breakwater at the north end of Priest Lake is intended to manage sediment from the upper lake while providing wave and erosion protection to landowners at the north end of Priest Lake.
Priest Lake Outlet Dam was constructed in 1950 to maintain lake levels in Priest Lake and manage downstream flows into Priest River. The current Priest Lake Outlet Dam, which was constructed in 1978, is owned by IDWR and operated by a contractor on behalf of IDWR. The dam is approximately 12 feet high with gates that regulate discharge. It does not have an emergency spillway.
Priest Lake is located on the Priest River in the northern Idaho panhandle. It is a significant draw for tourism and recreation in the area—adding to the economic impact of Bonner County. The area is known for the pristine variety of wildlife, clear and clean water, and recreational fishing opportunities.
In 2015, limited water supply and drought conditions in northern Idaho made maintaining the required summer lake level and downstream flow in the river very difficult. This situation, coupled with concerns about the breakwater structure and Thorofare access issues, increased interest in developing both operational and engineered improvements to the entire system.
In response to area stakeholders' concerns, the IWRB authorized funding to perform an evaluation of strategies and options that could meet the long-term water management solutions for the Priest Lake and Priest River system.