Prior Lake and Spring Lake have been identified for impairment of aquatic recreation (swimming) due to excess nutrients (phosphorus). As a result they have been placed on Minnesota's 303(d) list of impaired waters since 2002. Because of the exceedance, the Watershed District conducted a Total Maximum Daily Load (TMDL) study. A TMDL is defined as the maximum quantity of a pollutant that a water body can receive and continue to meet water quality standards for designated beneficial uses. The Spring Lake-Upper Prior Lake watershed is a developing watershed, with a 2000 Census population of about 25,000.
Map and location
Spring and Upper Prior Lakes are located in the Minnesota River Basin, North Central Hardwood Forest ecoregion in the southwestern suburban Twin Cities metropolitan area. The lakes are located in the City of Prior Lake and Spring Lake Township while the drainage area includes portions of Sand Creek Township. The tributary area to Upper Prior Lake is about 16,000 acres, or about 60 percent of the Prior Lake - Spring Lake Watershed District. Spring Lake is connected via a natural channel to Upper Prior Lake which discharges to Lower Prior Lake which outlets via a channel to the Minnesota River.
TMDL report and implementation plan
- Spring Lake and Upper Prior Lake TMDL Project: Final TMDL Report
- Spring Lake and Upper Prior Lake TMDL Project: EPA approval letter (Sept. 2011)
- Spring Lake and Upper Prior Lake: TMDL Implementation Plan
- Spring Lake Site-Specific Eutrophication Criteria Justification
- Spring Lake Site-Specific Eutrophication Criteria: July 16, 2016, EPA approval letter (wq-iw7-26o)
Eric Alms, Project Manager
Minnesota Pollution Control Agency
520 Lafayette Rd N
St. Paul, MN 55155