Silver Lake Watershed Treatment Project

This project will reduce phosphorus loading from the watershed tributary to Silver Lake. The project includes a combination of structural water quality improvements in the SLV-10 subwatershed north of the lake, retrofits (including iron enhanced sand filtration) to the Silver Lake bioretention basin, small scale best management practices (BMPs) throughout the watershed, and educational signage in Joy Park. The elements of this project will reduce phosphorus loading to Silver Lake by a combined 15 pounds per year or 40% of the current watershed load. This project will lower phosphorus concentrations and increase the frequency with which Silver Lake meets applicable Valley Branch Watershed District (VBWD) and MPCA water quality standards. Silver Lake is a 76-acre shallow lake bordering the cities of North St. Paul, Maplewood, and Oakdale in the VBWD. The lake receives runoff from an approximately 350-acre watershed of primarily residential land use. The lake is heavily used for recreation, including swimming and fishing. This intensive use is due in part to the presence of two parks adjacent to the lake: North St. Paul's Silver Lake Park along the south shore and Maplewood's Joy Park along the north shore. Other recreational uses include waterskiing, canoeing, and aesthetic viewing. Water quality in Silver Lake over the past 10 years has declined, as witnessed by a statistically significant increase in phosphorus concentrations and decrease in water clarity. The most recent 10-year average of total phosphorus concentration in Silver Lake is worse than the applicable MPCA standard, and the lake may be listed as impaired due to nutrients. Silver Lake was included in the VBWD WRAPS study, which identified strategies to restore lake water quality. Several elements of this project are among those strategies identified in the WRAPS study. In addition to improving water quality, the project will provide secondary benefits to habitat, recreation, and education.