Tongue River Watershed

FINAL SUPPLEMENTAL WATERSHED PLAN/ENVIRONMENTAL ASSESSMENT TONGUE RIVER CHANNEL STABILIZATION

The purpose of the proposed action is to provide watershed protection and flood damage reduction.

Increased channel incision on the Tongue River upstream of North Dakota Highway 32 has resulted in substantial, unplanned sediment load into Lake Renwick, threatening to fill the sediment pool by 2027 and then filling the recreation/permanent pool. If incision continues at the same rate, the reservoir would be completely filled with sediment by 2086, effectively turning Lake Renwick into a dry dam or requiring expensive dredging operations. The filling of the permanent pool will also impact the flood control benefits of the structure, including protected homes and cropland.

The preferred alternative will entail 1.8 miles of channel stabilization via levee removal, river restoration, grade control structures, bioengineering bank treatments, and floodplain revegetation to reduce downstream sediment delivery and halt the upstream progression of the incision. Reconnection of the channel to the natural floodplain, as well as floodplain excavations, will provide downstream flood control benefits.

Total Installation Cost: $4,777,600
Federal (NRCS) Contribution: $3,673,900

Current Status

The Watershed Plan-EA was authorized in May 2023 and final engineering design work has been completed.  The plan and design are ready for the installation phase. The Sponsor has decided to not more forward with the project at this time (spring 2024 decision).  

Resources

Tongue River Appendix D-9 Cultural Resources Survey available upon request