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Priest Lake Water Management Project

Project Phase 1: Study

The Priest Lake Water Management Study (Phase 1) was completed in February 2018. The study included the following recommendations:

  • Temporarily raising the surface level of Priest Lake three to six inches during the recreational season of dry years and integrating real-time streamflow data to allow more operational flexibility.
  • Outlet structure improvements to the scour apron, modifying and strengthening gates, and electrical gate operation.
  • Replace the current existing porous breakwater with an impervious sediment retention feature and dredging a portion of the Thororfare channel.

Project Phase 2: Preliminary Engineering & Design

The work of Phase 2 is a continuation of the work, conclusions, and recommendations outlined in the Phase 1 report. Phase  2 project goals include managing lake levels (maintaining a three-foot level at the USGS outlet gage during the recreational season and developing lake level operational strategies during dry and low water years), maintaining minimum flow requirements downstream of the outlet dam, and providing sustainability for the Thorofare (promoting self sustaining improvements to improve Thorofare access, navigability). Phase 2 for preliminary engineering design of the Outlet Thorofare and the Priest Lake Outlet Dam was completed in 2019. 

Project Phase 3: Engineering Design & Preparation of Construction Documents

The work of Phase 3 was a continuation of previous phases with the intent of performing final engineering design and preparation of construction documents for a contractor to construct the needed improvements.  Construction documents for both the Outlet Thorofare and the Priest Lake Outlet Dam were completed in 2020.

Project Phase 4: Construction Improvements

The work of Phase 4 includes the construction of both the Outlet Thorofare and the Priest Lake Outlet Dam.  The Outlet Thorofare was successfully completed during the 2020/2021 winter and accomplished the project goal of creating an impervious sediment retention feature for the breakwater structure and dredging of the silted-in channel.

Construction of the Priest Lake Outlet Dam begin in November 2020 and was partially completed.  Outle Dam improvements successfully completed included extension of the dam gate height six inches.  Other aspects of the Outlet Dam were partially completed including concrete and armor stone apron extensions.  Challenges during construction led to severing the construction contract between IWRB and the contractor. 

Construction documents have been updated to reflect current dam conditions and the IWRB intends to bid for the construction improvements to the Priest Lake Outlet Dam.  Construction to finish the Outlet Dam improvements is anticipated during winter of 2023/2024.

Brief History

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.

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