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Lower Grand Watershed Interactive Tool (WIT) - Nonpoint Source Pollutants

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nonpoint factWhat is nonpoint source pollution?

Nonpoint source pollution is caused when rain, snowmelt, or wind carry pollutants off the land and into water bodies.

Click here to learn more about Typical Nonpoint Source Pollutants in Michigan Waters (which are also found in the Lower Grand River Watershed)

bridge in wintertime

Typical Nonpoint Source Pollutants Impacting Michigan Waters

nonpoint source definitionNonpoint source pollutants are any of the substances listed below that can degrade the water quality by impairing the designated use(s) of the water.

Click on the links for more information about any of the pollutants below.

  • Animal manure - Manure is a source of nutrients, salts, organic matter, and pathogens that can degrade water quality.
  • Depressed dissolved oxygen - When the oxygen dissolved in water and readily available to aquatic organisms is below optimal levels.
  • Hydrologic flow function - When the natural hydrology of the watershed changes due to increase in storm water runoff.
  • Metals - Toxic substances, such as mercury and lead, that come from urban runoff or atmospheric deposition.
  • Nitrogen - An element that at certain levels can cause excessive algae and aquatic weed growth.
  • Organic matter - Residue from plant or animal origin (including leaves and grass clippings). In excessive amounts organic matter can lower dissolved oxygen levels.
  • Pathogens - Human disease-causing bacteria or viruses.
  • Pesticides - Chemical substances used to kill pests such as weeds, insects, algae, rodents, and other undesirable agents.
  • Petroleum and petroleum by-products (oil and grease) - Urban pollutants that are transported by rainfall from roads, parking lots, and improper storm drains.
  • Salts - Chemical compounds from winter road de-icing, septic systems, and water softener outwash.
  • Sediment - Soil that is transported by air and water and deposited on the stream bottom.
  • Thermal pollution - An elevation in water temperature that stresses fish and aquatic insects.

Source: Brown, E., A. Peterson, R. Kline-Robach, K. Smith, L. Wolson. 2000. Developing a Watershed Management for Water Quality: An Introductory Guide. MSU Institute of Water Research, MSU Extension, and MI DEQ Nonpoint Source Program.


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Grand Rapids, MI 49503
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Page last modified March 13, 2014