Otter Tail River Restoration

The Otter Tail River is located in west-central Minnesota. Its Lower Otter Tail River (LOTR) reach is impaired for sediment. The LOTR begins at the dam of Orwell Reservoir near Fergus Falls and ends 48 river miles downstream at the confluence with the Bois de Sioux River at Breckenridge. No point sources contribute directly to the LOTR. Consequently, the turbidity impairment must be addressed through non-point measures. Current stream instability and bank erosion is largely a result of an 18-mile channel straightening completed by the Army Corps of Engineers in the 1950s. This channel straightening reduced channel length and induced headcutting which has been a major contributor to channel instability and bank failure resulting in excessive sediment loading since that time. Bank instability is a significant contributing factor to the turbidity impairment in the LOTR. A TMDL study for this reach of the river was completed in 2006 with an implementation plan completed in 2007. An estimated 17 percent reduction in the 40,400 tons/year annual sediment load is necessary to meet the state standard. Since 2007, the Wilkin SWCD installed BMPs to hold the water back in contributing drainage systems and release it slower into the LOTR. The SWCD work has resulted in the retrofit of 40 miles of legal ditch systems with sediment controls (side inlets) and 300 acres of buffer strips. Cover cropping promotion resulted in excess of 20,000 acres of annual cover crops. The remaining implementation strategy will need to address in-stream sediment sources which will require a detailed channel restoration plan to stabilize streambank erosion and encourage natural stream functions. The detailed plan will provide a coordinated framework for future channel restoration. When implemented, the LOTR is expected to once again meet state standards. The Wilkin SWCD and Buffalo-Red River Watershed District are partners to complete this project