2016 Lake Minnewaska Targeted Subwatershed Project Phase III
Projects and Practices 2016: Laws of MN 2015 First Special Session Chapter 2, Article 7, Section 7
The proposed erosion and sediment control projects will assist in alleviating areas of steep grade, and allow for longer periods of infiltration to occur, and temporary storage with underground outlets. These projects have the potential to reduce sediment load by 518 tons/year, and 446 lbs of phosphorus/year.
LOCAL LEVERAGED FUNDS
Pope SWCD has 9 motivated landowners with 21 WASCOBs, 1 lined waterway, and 1 shoreline restoration in two priority sub watersheds (Trappers Run and Minnewaska). Based on averages calculated from recently constructed WASCOBs in the West Central Area II these projects have the potential to reduce TSS by 518 T/year, and 446 lbs./year of TP. This project will provide a secondary benefit to improve downstream water quality to Lake Emily. The project will result in meeting 99% of the Lake Emily TP lbs/yr. TMDL goal from flowage from Lake Minnewaska, 8% TP lbs/yr goal for Strandness, and a total reduction of 6% of the 35% TMDL goal needed to delist Lake Emily. All lakes but Minnewaska are impaired for excessive nutrients and are included in the MPCA 8 Lake TMDL study. Lake Minnewaska (protection status) has impaired lakes upstream and downstream; during 2014/2015 storm events monitoring samples are exceeding state standards. Lake Minnewaska is the 13th largest lake and is a highly valued water resource for public use and at high risk of becoming impaired. Monitoring shows TP averages from 2005-2013 have declined. Since 2005 about 4-6 times a summer heavy rain events are causing severe gully erosions. The water quality trends for Lake Minnewaska are holding based on Pope County Coalition of Lakes Association monitoring but without projects being implemented these trends are at risk to decline. Citizen stream monitoring data in 2014/2015 show storm events that secchi tube readings go from 100 cm + on an average day in tributaries to 7 cm. The spike is coming from ravine and gully erosion within the subwatershed. Utilizing the Water Quality Decision Support App (WQDSA) completed to identify areas where water and sediment control basins and erosion control projects should be implemented has targeted implementation efforts. WASCOBs are in the TMDL implementation plan (section 1.1 page 3) and the Pope County Water Plan (2-25) as a method of lowering the annual TSS and TP.