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The MPCA studies, monitors, and regulates numerous water pollutants to protect human health and the environment. At the state level, three agencies share the monitoring and control of pollutants:

  • The MPCA focuses on pollutants and stressors in lakes and streams (surface waters) and groundwater aquifers.
  • The Minnesota Dept. of Agriculture focuses on the effect of agricultural chemical on surface waters and groundwater.
  • The Minnesota Dept. of Health focuses on drinking water, which comes from both surface waters and groundwater.

Choose a pollutant below to learn where it comes from and its effects on human health and the environment, and monitoring and regulation information.

In addition to the pollutants listed below, Minnesota water quality rules contain standards (acceptable levels) for substances, characteristics, and pollutants. Many of these are not widespread problems, in part because the rules have led to adequate controls.

1,4-dioxane

The main use of 1,4-dioxane was as a stabilizer for chlorinated solvent 1,1,1-trichloroethane (often used for industrial purposes). 1,4-dioxane can also be an unintended contaminant in the production of certain products, including some cleaners, detergents, adhesives, inks, automotive fluids, etc.

Bacteria

Bacteria in Minnesota lakes and streams mainly come from sources such as failing septic systems, wastewater treatment plant releases, livestock, and urban stormwater. Waste from pets and wildlife is another, lesser source of bacteria.

Chloride

Chloride from both de-icing salt and water softener salt gets into lakes and streams, and groundwater that supplies drinking water. It takes only one teaspoon of salt to permanently pollute five gallons of water. Once in the water, there is no feasible way to remove the chloride.

Contaminated sediments

Some pollutants attach to suspended particles in the water and subsequently settle out to the bottom sediment.

Heavy metals

Heavy metals are an ill-defined group of inorganic chemical hazards including lead, chromium, arsenic, and cadmium.

Mercury

Mercury is a naturally occurring element that is toxic to humans and animals. At room temperature, mercury is a silvery, liquid metal, but it can also evaporate and become airborne. Mercury does not break down into less toxic substances, like some pollutants.

Nitrogen

Nitrogen is a nutrient that pollutes state waters, and its concentration in many rivers has been increasing from historic natural levels over time due to human influences.

Perchloroethylene/tetrachloroethylene (PCE or Perc)

Perchloroethylene or tetrachloroethylene (PCE or Perc) is an organic chemical used in dry cleaning, as a solvent and degreaser, in auto paint and auto repair shops, and in some consumer products.

Petroleum

Petroleum spills from pipelines, trains, trucks, storage tanks, and other sources have damaged natural resources throughout Minnesota.

PFAS

Per- and polyfluoroalkyl substances (PFAS) are a group of over 5,000 human-made chemicals that do not break down over time.

Phosphorus

Excess phosphorus, from both regulated and non-regulated sources, is harming Minnesota waters.

Polycyclic aromatic hydrocarbons (PAHs)

Polycyclic aromatic hydrocarbons (PAHs) are a class of more than 100 chemicals that occur naturally in coal, crude oil, and gasoline, and are also present in products made from fossil fuels, such as coal-tar pitch, creosote, and asphalt.

Sediment

Sediment is composed of loose particles of sand, clay, silt, and other substances. Sediment flows into Minnesota lakes, rivers, and streams via runoff in both urban and rural areas.