3.4.3 Impaired Waters

The federal Clean Water Act requires states to adopt water quality standards to protect the nation’s waters. These standards define how much of a pollutant can be in a surface and/or ground water while still allowing it to meet its designated uses, such as for drinking water, fishing, swimming, irrigation or industrial purposes.   The Clean Water Act requires states to publish, every two years, an updated list of streams and lakes that are not meeting their designated uses because of excess pollutants. The list, known as the 303(d) list or the list of Impaired Waters, is based on known violations of water quality standards.

Waters that are Impaired must undergo a Total Maximum Daily Load (TMDL) process.  This process involves the following phases:

  1. Assessment and listing;
  2. TMDL study to determine the source or sources of the pollutant or stressor, a determination of the maximum amount of that pollutant or stressor that can be allowed, and an allocation of that maximum amount to the various sources;
  3. An implementation plan that sets forth strategies for reducing pollutant loading or alleviation of the stressor; and
  4. Monitoring the effectiveness of implementation efforts.

A number of waterbodies in the watershed have been designated Impaired Waters.  The District is in the process of completing TMDLs for nine lakes that are nutrient impaired.  

Table 16.  Impaired Waters in the Minnehaha Creek Watershed.

Waterbody

Affected Use

Pollutant or Stressor

Year of Listing

Minnehaha Creek

Aquatic life

Fish IBI

2004

Virginia

Aquatic recreation

Aquatic consumption

Excess nutrients

Mercury FCA*

2004

2006

Zumbra-Sunny

Aquatic consumption

Mercury FCA

1998

Parley

Aquatic recreation

Excess nutrients

2002

Steiger

Aquatic consumption

Mercury FCA

1998

Wasserman

Aquatic recreation

Aquatic consumption

Excess nutrients

Mercury FCA

2002

1998

Powderhorn

Aquatic recreation

Aquatic consumption

Excess nutrients

Mercury FCA

2002

2006

Harriet

Aquatic consumption

Mercury FCA

1998

Hiawatha

Aquatic recreation

Excess nutrients

2002

Nokomis

Aquatic recreation

Aquatic consumption

Aquatic consumption

Excess nutrients

Mercury FCA

PCB FCA

2002

1998

2002

Diamond

Aquatic recreation

Excess nutrients

2002

Calhoun

Aquatic consumption

Mercury FCA

1998

Brownie

Aquatic recreation

Aquatic consumption

Excess nutrients

Mercury FCA

2004

1998

Cedar

Aquatic consumption

Mercury FCA

1998

Lake of the Isles

Aquatic recreation

Aquatic consumption

Excess nutrients

Mercury FCA

2002

1998

Minnetonka

Aquatic consumption

Mercury FCA

1998

Christmas

Aquatic consumption

Mercury FCA

1998

Long

Aquatic consumption

Mercury FCA

1998

Twin

Aquatic recreation

Excess nutrients

2006

Grass

Aquatic recreation

Excess nutrients

2006

*FCA = Fish consumption advisory.  Impacts of mercury are mainly regional in expression, so the initial approach by the MPCA will be to complete regional or statewide mercury TMDL reports.

Source:  Minnesota Pollution Control Agency

According to monitoring data, the following resources do not currently meet state nutrient standards and may be in the future designated as impaired waters:

Dutch Lake Mooney Lake Jennings Bay
Gleason Lake Stone Lake West Arm
Langdon Lake Lake Auburn East  
Long Lake Lunsten Lake  
Tanager Lake Halsted Bay