2023 Lower Otter Tail River Gully Stabilization Project

The Wilkin Soil and Water Conservation District (SWCD) will partner with the Buffalo Red River Watershed District (BRRWD) and landowners to stabilize 20 high priority gullies that are contributing sediment to the Lower Otter Tail River (LOTR). The LOTR is in the Otter Tail Planning region in the Buffalo-Red River Watershed Comprehensive Watershed Management Plan (BRRWD CWMP). The plan identifies a 10-year goal of reducing the sediment loading from the Otter Tail Planning Region by 9186 tons/yr. The LOTR is a significant source of this sediment, and this project would provide 850 tons/year (approximately 9%) of the 10-year goal identified. The BRRWD CWMP also lists reducing Phosphorus levels as a goal. This project would reduce phosphorus levels by 786 lbs/yr. or approximately 60% of the 10-year goal identified. The Lower 8.2 miles of the Otter Tail River is listed as an impaired water for exceeding the turbidity standard for aquatic life. The Minnesota Pollution Control Agency completed a Total Maximum Daily Load (TMDL) report for the Lower Otter Tail River (2021) and determined that 6,868 tons of sediment per year need to be removed for the Lower Otter Tail River to no longer be listed as impaired. When all 20 gullies are stabilized, Sediment Load will be reduced by an estimated 850 tons per year. The sediment reduction associated with this project is 12 percent of the 6,868 tons per year goal set by the TMDL plan at the sampling site in Breckenridge. The Stream Power Index (SPI) tool was used to identify each gully location and the and the Prioritize, Target, and Measure application (PTMapp) was used to prioritize each gully and to quantify the sediment, total phosphorus and total nitrogen loads to the Otter Tail River. In 2018 the Wilkin SWCD received a Clean Water Fund grant to address gullies on the LOTR. This grant resulted in 46 grade stabilization/side inlet structures and a reduction of 944 tons/yr. of sediment. The funds were all used and additional projects were identified and surveyed. These projects are ready for construction awaiting funding. Along with these BMP's the BRRWD is working on stabilizing a head-cut in the Lower Otter Tail River with an additional 2023 CWF grant (Lower Otter Tail River Restoration - Head-cut Stabilization). These projects together will make significant progress towards the sediment reduction goals in the BRRWD CWMP for the Otter Tail Planning Region.