Lake Sarah - Excess Nutrients: TMDL Project

Minnesota's Impaired Waters and TMDLs

Background

Lake Sarah is a 552-acre lake located approximately 18 miles west of Minneapolis in west central Hennepin County. The lake has a maximum depth of 60 feet, mean depth of 18.2 feet, and is used extensively for fishing, boating and aesthetic viewing. The majority of the lake’s west end is within Lake Sarah Regional Park, operated by Three Rivers Park District. Lake Sarah receives runoff from a 4,608-acre predominantly agricultural watershed which contains portions of five municipalities — Greenfield, Independence, Corcoran, Loretto, and Medina. Portions of the watershed are undergoing rapid urbanization, although the majority of the new residential lots are large.

Lake Sarah receives excess nutrient loading from the watershed and from internal recycling mechanisms. The internal loading factor is especially critical in Lake Sarah because an abundant curly-leaf pondweed population provides a phosphorus pulse to the lake when it undergoes senescence in late June each year. As a result of the excessive phosphorus loading, the lake experiences nuisance algae blooms in the summer, severely restricting recreational use.

In 2006, Lake Sarah was placed on the Minnesota Pollution Control Agency’s 303(d) list of impaired waters because of excess nutrients (phosphorus). Inclusion on the 303(d) list requires completion of a Total Maximum Daily Load (TMDL) study to determine the magnitude of the impairment, identify pollutant sources, and allocate pollutant loading among the permitted and non-permitted sources in the lake’s drainage basin.

Map and location

Lake Sarah is located near the cities of Independence and Greenfield in the western Twin Cities Metro Area, Hennepin County, within the North Fork Crow River watershed in the southern portion of the Upper Mississippi River Basin.

 

• 2008 Map of Impaired Lakes in the Twin Cities Metropolitan Area

For a map of this impairment, see the Google map below or the Impaired Waters Viewer.

TMDL report and implementation plan

• Fact Sheet
• Final TMDL Report(wq-iw8-13e)
• EPA Approval Letter (April 25, 2011) (wq-iw8-13g)
• TMDL Implementation Plan (September 16, 2011) (wq-iw8-13c)

Other documents

• Work Plan to develop the Lake Sarah Excess Nutrients TMDL
• Progress Report (8/1/08) for Lake Sarah Excess Nutrients TMDL
• Lake Sarah Water Quality

Meetings and events

The Lake Sarah Stakeholders Committee, a group of citizens concerned about the water quality of the lake, has been meeting since 2005. All meeting information, including agendas, minutes, presentations and electronic handouts can be found in PDF document below. This document is bookmarked for ease in searching for specific meeting details. 

• Lake Sarah Stakeholders Committee Meetings, 6:30-8:30 p.m., Independence City Hall
  • January 15, 2008
  • February 25, 2008
  • April 7, 2008
    • Meeting Notes
  • June 16, 2008
    • Meeting Notes
    • Presentation: Lake Sarah TMDL (John Barten) 
  • August 18, 2008
    • Meeting Notes
    • Presentation: Lake Sarah TMDL(John Barten) 
  • October 20, 2008
    • Meeting Notes
  • December 3, 2008
    • Meeting Notes
  • March 2, 2009, May 18, 2009, January 25, 2010
    • 2009-2010 Meeting Information (wq-iw8-13m)

Links

• Local Sponsor: Pioneer-Sarah Creek Watershed Management Commission
• Project Lead: Three Rivers Park District
• Project Partner: Lake Sarah Improvement Association
• Project Partner: Hennepin County Department of Environmental Services
• MPCA: Upper Mississippi River Basin
• MPCA: Minnesota’s Impaired Waters and TMDLs

Information contact

Rachel Olmanson
Minnesota Pollution Control Agency
520 Lafayette Road N
St. Paul, MN 55155
651-757-2473
rachel.olmanson@state.mn.us