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Indicator 6 4 : Water quality in lakes and rivers

Goal: Minnesotans will improve the quality of the air, water and earth. Continuously improving the health of Minnesota's natural systems not only ensures continued access to the raw materials that fuel Minnesota's economy, but also protects the irreplaceable roles of healthy natural systems, such as flood and pest control, moderation of the climate and pollination of crops.

Rationale: The suitability of Minnesota's lakes, rivers and streams for swimming and aquatic life is a good indicator of water quality.

Percentage of monitored lakes acres suitable for swimming


Data source: Minnesota Pollution Control Agency

Percentage of monitored river miles suitable for swimming


Data source: Minnesota Pollution Control Agency

Percentage of monitored river miles supporting aquatic life


Data source: Minnesota Pollution Control Agency

About this indicator: Of the sampling of lakes and rivers that are monitored, more lake acres became unswimmable, fewer river miles supported aquatic life, but more river miles became suitable for swimming between 1994 and 2000. Defining a body of water as swimmable is based largely on the presence of fecal coliform and E-coli bacteria, while suitability for aquatic life is based on the presence of toxins (such as ammonia, chlorine and heavy metals), water clarity and the availability of oxygen in the water.

The percentage of monitored lake acres suitable for swimming slipped from 79 percent in 1994 to 64 percent in 2000. The percentage of monitored river miles supporting aquatic life dropped from 73 percent to 65 percent during the same six years. However, the percentage of monitored river miles suitable for swimming rose from a low of 39 percent in 1994 to 62 percent in 2000.

Things to think about: The 1972 federal Water Pollution Control Act set a goal of ensuring that U.S. waters are "swimmable" and "fishable." Minnesota has made progress in controlling end-of-pipe discharges from wastewater treatment plants and industrial plants. However, the challenges posed by sources of pollution such as water runoff from cities and agricultural areas are increasing.

Technical notes: In 2000, the most recent year for which data is available, the figures are based on monitoring 53 percent of lake acres and 1.12 percent of river miles for their swimmability, and not quite five percent of river miles for their ability to support aquatic life. The Minnesota Pollution Control Agency reports its findings on about one-third of Minnesota's 10 watersheds every two years.


  • Minnesota Pollution Control Agency,
  • U.S. Environmental Protection Agency,

Related indicators:

Other related indicators:

  • Amount of groundwater and surface water used, by type of use (Minnesota Department of Natural Resources, Division of Waters, water appropriation permits,
  • Levels of atrazine, a common agricultural pesticide, in ground water in southwest Minnesota and the central sand plain (Minnesota Department of Agriculture,
  • Water quality in three watershed basins: Minnesota River, Lake Superior, Red River of the North (Minnesota Pollution Control Agency:

Technical problems? Contact: