Polluted Runoff

When it rains or snow melts, water collects pollutants from the surfaces it travels over. This polluted runoff washes into lakes, rivers and streams, causing many problems for these waters and the plants, animals and people that use them.

Polluted runoff is one of the main components of “nonpoint source” water pollution and can include nutrients like phosphorus, agricultural chemicals, sediments and other materials. Runoff most often comes from agricultural lands, urban areas, industrial areas and construction sites. When this runoff enters water bodies, its pollutants can cause increased algae growth, kill fish, harm ecosystems, impair waterways for recreation and threaten human health.

Key Points

  • Polluted runoff is Wisconsin’s No. 1 water quality problem, degrading or threatening an estimated 90% of inland lakes.[1]
  • 380,000 acres of Wisconsin’s lakes and reservoirs, and more than 3,300 miles of streams and rivers are unable to support recreation and wildlife as a result of polluted runoff.[2]
  • Manure from Wisconsin’s approximately 14,000 active livestock operations is a major cause of polluted runoff, because it contains nutrients like phosphorus that can cause toxic algae blooms when washed into nearby lakes and streams.[2]
Clean Wisconsin's Work

Polluted runoff is a top threat to our waterways. Clean Wisconsin is working to reduce this threat, with emphasis on managing sources of agricultural runoff and reducing phosphorus pollution. We continue to push for passage and implementation of strong federal or state policies that adequately address polluted runoff. We also advocate proper management, monitoring and accountability of runoff sources as specified by policies already in place. We want to meet water quality standards in Wisconsin and make our waterways clean and safe for all to enjoy.

In 2010, Clean Wisconsin helped pass a precedent-setting phosphorous pollution rules package that enables farmers and municipalities to work together to curb phosphorus pollution. These rules, which are some of the most innovative in the nation, give phosphorus contributors flexibility to reduce their runoff and discharge in a cost-effective, collaborative manner. Clean Wisconsin is now involved in a pilot project in Dane County’s Yahara Lakes to demonstrate these rules and help establish a model for the rest of the state.

Clean Wisconsin Media and Materials


Questions and Answers

What is polluted runoff?
Polluted runoff refers to rainwater or snowmelt that accumulates pollutants while flowing over land and then carries those pollutants to water systems.

What kind of pollutants are in polluted runoff?
Depending on the type of surface that it travels over, runoff can contain pollutants like excessive nutrients, agricultural and industrial chemicals, herbicides and pesticides, salts and other potentially harmful materials. The most common runoff pollutants in Wisconsin are excess nutrients, followed by sediment and various chemicals.

Where does polluted runoff come from?
There are many urban and rural sources of runoff pollution. Agricultural lands are the primary source of runoff that contains excessive nutrients and pesticides, although these pollutants can be present in urban runoff as well. A large portion of sediment comes from construction sites and development projects as well as croplands as a result of disturbed or bare soils. Storm water that runs directly into storm sewers from urbanized areas can contain anything from oils and grease to heavy metals and other toxins.

What type of polluted runoff from agricultural sources are of largest concern?
Manure applied to agricultural land is a major source of excessive nutrients, particularly phosphorus, in surface runoff. When applied in excess, these nutrients run off into waterways causing problems like eutrophication (see our Phosphorus Pollution page). Unfortunately for Wisconsin, large dairy operations produce particularly significant amounts of manure.[3] In addition to nutrients, manure can contain other harmful substances like bacteria, hormones and endocrine disruptors. Agricultural runoff can also include commercial fertilizers, pesticides and herbicides.

How do agricultural sources contribute sediment to runoff?
As a result of certain farming practices, farmlands can contribute a great deal of sediment to runoff. Each spring, land is disturbed as farmers plow and plant their fields. This exposed and recently disturbed land is much more prone to erosion and transport from rainwater than other soils that are held in place from vegetation cover. Excess sediment can be problematic for nearby waters.

What kinds of pollutants runoff from urbanized areas?
Urban areas can produce a large amount of untreated stormwater, especially when storm sewers drain directly to local waters. While these sewers can help to reduce flooding, they also collect and transport a wide variety of pollutants from everything that the storm water contacts, such as buildings, yards, streets, and sidewalks. These pollutants can include oils, heavy metals, nutrients, pesticides, bacteria, salts and other substances.

How do construction sites contribute to polluted runoff?
Construction sites can contribute a wide variety of pollutants to runoff. Since construction sites often include land that is disturbed and left bare (with no vegetation or other cover holding sediment in place), they have a higher potential for losing sediment during runoff events. In fact, according to the Wisconsin Department of Natural Resources, an average construction site loses 30 tons of sediment per acre to runoff into nearby waterways.[4]

What impact does sediment from polluted runoff have on waterways?
Sediment pollution from polluted runoff can have both localized impacts and more widespread effects on water quality. An example of localized impacts are those from urban sediments (such as metal flakes, particles from exhaust and chimneys, bits of tires and brakes, chunks of pavement and other sources), which can negatively impact swimming and health in areas when people use polluted waters and beaches for recreation.[5] The more widespread impacts tend to be at the ecosystem level, where the concerns are related to the smaller particles that cause waters to become turbid or cloudy. For example, when these types of sediments get into lakes and rivers, they can directly harm fish species that are unable to tolerate the suspended sediments, as well as impacting many aquatic insects that are vital to the health of the ecosystem. The sediment can also fill in spaces between rocks that those aquatic insects would normally use for shelter, bury fish spawning areas, and affect eggs and young fry.[1] By pushing out native species that can’t tolerate the changed water conditions, sediment pollution can also then make room for invasive species like Asian carp that thrive in those conditions.

What impact do excessive nutrients in polluted runoff have on waterways?
Nutrient pollution, mainly from agricultural runoff, can lead to harmful algae blooms and excessive plant and bacteria growth. Algae can overtake affected waters, causing oxygen depletion, fish kills and other negative impacts to the ecosystem. Algae can also impair our uses of the water, such as swimming, boating and fishing. Some kinds of algae can even produce toxins with the potential to directly harm animals and humans.

What can be done to prevent polluted runoff?
One way to get involved in helping with the problem of polluted runoff is to participate in programs like the Citizen-based Water Monitoring Network, organized by the University of Wisconsin Extension and WDNR. Even basic monitoring of stream health can catch the warning signs of excessive nutrients or other pollutants.

Individual choices for homes, lawns, gardens and driveways can help to reduce runoff pollution from urban areas, as can practices such as environmentally friendly lawn care and proper fall leaf management.[6][7]

Farmers and others working in agriculture are encouraged to work with the WDNR and other groups to implement runoff-reducing management practices, such as properly managing manure.[8]

Policies are also necessary to require additional monitoring of surface runoff and its sources. This will allow better targeting in runoff prevention efforts; surface runoff is currently monitored and regulated much less than specific (point) sources of water pollution.

Quick Facts
  • Lakes, streams and ponds are commonly polluted with pesticides and fertilizers, sediment, oil and antifreeze, toxic chemicals and even pet waste from polluted runoff.[5][9]
  • The average yearly precipitation in Wisconsin is between 30 and 36 inches, equal to about one million gallons of water per acre.[10]
  • Commercial areas typically create more runoff per square foot than other land uses, due mostly to large areas of impervious surfaces such as roofs and parking lots.[10]
  • A typical city block can generate over 5 times more runoff than a woodland area of the same size.[5]
  • Preventing polluted runoff can have substantial positive impacts on property values:
    • A study of lakefront property values in Minnesota’s Mississippi Headwater Region found that each additional meter of water clarity resulted in an average increase in price of $45.64 per frontage food, totaling an aggregate increase in property values of $5.9 million for the entire region.[11]
    • A study in Maine found that property values would decline approximately $10.5 million with a three-foot decline in water clarity.[12]
  • Studies indicate that once impervious surfaces in watershed exceed ~8%, significant water quality impacts result, including impacts on fish, frogs, aquatic insects, and the animals that feed on them.[13][14]
  • Drainage from one acre of commercial area can contain 1,500 pounds of suspended solids, 2.6 pounds of phosphorus, 31 pounds of nitrogen, and 3.3 pounds of toxic metals.[3]
  • Farmers and ranchers can reduce erosion and sedimentation 20 percent to 90 percent by applying management practices that control the volume and flow rate of runoff water, keep the soil in place, and reduce soil transport.[15]
  • Livestock produce over one billion tons of manure in the United States per year.[16]
Wisconsin Data, Trends, and Legislation

Polluted runoff is the No. 1 threat facing Wisconsin’s waters. Wisconsin is rich in water resources that support the lifestyle and economy of the state. Pollutants like phosphorus, sediment, bacteria and toxins in surface runoff can significantly harm aquatic plants and animals, raise water temperatures and hurt water quality. At the same time, it has impacts on recreation, beaches and even human health.

  • Polluted runoff is Wisconsin’s top water quality problem, degrading or threatening an estimated 90% of inland lakes.[1]
  • Vilas County estimated that an additional 30 cm (roughly 12 inches) of water clarity resulted in a 3.6% increase in lakefront property values.[17]
  • 380,000 acres of Wisconsin’s lakes and reservoirs and more than 3,300 miles of streams and rivers are polluted and unable to support recreation and wildlife.[2]
  • Wisconsin streams and lakes in watershed with greater than 12% impervious surface coverage consistently had poorer fish communities than waters in less developed watersheds.[18][19]
  • Nutrient pollution limits fish and other aquatic life in more than 220,000 acres of freshwater lakes and reservoirs in Wisconsin.[3]
  • Turbidity — high levels of suspended solids like sediment or algae — is a problem in 150,000 acres of Wisconsin lakes.[3]
  • Construction sites are responsible for more sediment pollution of Wisconsin’s waters than any other source; in contrast, an acre of cropland loses one to 10 tons annually. Sediment contributes to the impairment of 1,800 miles of rivers and streams and 183,000 acres of inland lakes.[3]
  • Research on urban streams in Wisconsin has shown high concentrations of suspended solids, bacteria, heavy metals, oil, grease and polyaromatic hydrocarbons as a result of stormwater discharges.[2]
  • Approximately 14,000 active livestock operations exist in Wisconsin. Manure from livestock operations contains organic materials, nitrogen, phosphorus and other water pollutants.[2]
  • Concentrated animal feeding operations (CAFOs) make up less than 1% of Wisconsin’s farms but produce 10% of the manure.[1]
  • In 2009, 7 percent of water samples collected at the most popular Great Lakes beaches in Wisconsin had excessive levels of bacterial pollution and beaches were closed or deemed risky for recreation 401 times.[4]

Current Law

Wisconsin’s management of runoff pollution centers around Administrative codes governing nonpoint source pollution in the state. These rules began coming into effect on October 1, 2002, after a multi-stakeholder effort to improve the Wisconsin Department of Natural Resources’ nonpoint source pollution abatement program that started in 1997.[20] These rules include:

  • NR 151: Runoff Management
  • NR 216: Storm Water Discharge Permits
  • NR 217: Effluent Standards and Limitations for Phosphorus
  • NR 243: Animal Feeding Operations
  • ATCP 50: Soil and Water Resource Management Program

Wisconsin’s shoreland zoning rule (NR 115) requires that all counties adopt a shoreland zoning ordinance that meets minimum standards for shoreland protection established in the rule. Recognizing that land use shoreland areas substantially affects water quality, the purpose of these protections is to “limit the direct and cumulative impacts of shoreland development on water quality; near-shore aquatic, wetland and upland wildlife habitat; and natural scenic beauty.”

Other Current Laws

There are a great deal of other laws and policies that govern nonpoint source pollution, storm water and other runoff in the state of Wisconsin. For example, the Wisconsin Department of Transportation’s Trans 401 code is complimentary to NR 216 in managing transportation projects.

Proposed Legislation

Currently there is no proposed legislation.  Work is being done to implement all aspects of these relatively new rules.


Cited Resources
  1. Wisconsin Lakes. 2012. Polluted Runoff. Web. Retrieved 2012 from: http://www.wisconsinlakes.org/index.php/polluted-run-off
  2. Wisconsin Department of Natural Resources. 2010. 2010 Water Quality Report to Congress 2010. WDNR Pub WT-924-2010
  3. University of Wisconsin Extension and Wisconsin Department of Natural Resources. 2009. Total Suspended Solids: the Hows and Whys of Controlling Runoff Pollution.
  4. Natasha Kassulke. 2003. Reining in Polluted Runoff. Wisconsin Natural Resources Magazine.
  5. U.S. Environmental Protection Agency. 2003. Urban Non Point Source Fact Sheet. Web. Retrieved 2012 from http://water.epa.gov/polwaste/nps/urban_facts.cfm
  6. Sarah Witman. 2012. Waste-B-Gon: Smart lawncare practices for your home. Clean Wisconsin Blog. Web. Retrieved 2012 from http://blog.cleanwisconsin.org/index.php/2012/07/10/waste-b-gon-smart-lawncare-practices-for-your-home/
  7. Amanda Wegner. 2011. Fall’s Collection Call: 3 ways to responsibly dispose of leaves. Clean Wisconsin Blog. Web. Retrieved 2012 from http://blog.cleanwisconsin.org/index.php/2011/11/16/falls-collection-call-3-ways-to-responsibly-dispose-of-leaves/
  8. Wisconsin Department of Natural Resources. 2013. Manure spills response, planning and prevention. Web. Retrieved 2013 http://dnr.wi.gov/topic/AgBusiness/ManureSpills.html
  9. University of Wisconsin Extension. 1999. Pet Waste and Water Quality. GWQ006 Pet Waste and Water Quality, R-11-99-10M-20-S, DNR WT-534-99
  10. David Liebl. 2007. Managing Stormwater Runoff, A Self Assessment Guide for Wisconsin Businesses. Solid and Hazardous Education Center, University of Wisconsin Extension.
  11. Charles Krysel et al. 2003. Lakeshore property values and water quality: evidence from property sales in the Mississippui headwaters region.
  12. Maine Department of Environmental Protection Lake Assessment Program. 2000. More on Dollar and Sense: The Economic Impact of Lake Use and Water Quality.
  13. Brabec E, Shulte S, Richards PL. 2002. Impervious surfaces and water quality: a review of current literature and its implications for watershed planning. Journal of Planning Literature 16: 499-514.
  14. Woodford JE and Meyer MW. 2003. Impact of lakeshore development on green frog abundance. Biological Conservation 110: 277-284.
  15. U.S. Environmental Protection Agency. 2005. Protecting Water Quality from Agricultural Runoff. EPA 841-F-05-001
  16. Amanda Cuellar and Michael Webber. 2008. Cow power: the energy and emissions benefits of converting manure to biogas. Environmental Research Letters 3(2008)034002
  17. Papenfus MM and Provencher B. 2005. A hedonic analysis of environmental zoning: lake classification in Vilas County, Wisconsin.
  18. Wang L, Lyons J, Kanehl P, Bannerman R, Emmons E. 2000. Watershed urbanization and changes in fish communities in Southeastern Wisconsin streams. Journal of the American Water Resources Association 36: 1173-1187.
  19. Wang L, Lyons J, Kanehl P. 2001. Impacts of urbanization on stream habitat and fish across multiple spatial scales. Environmental Management 28: 255-266.
  20. Wisconsin Department of Natural Resources. 2002. Wisconsin’s Runoff Rules.


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Please cite this resource as: Clean Wisconsin, Inc. “Polluted Runoff.” Clean Wisconsin Enviropedia. Retrieved from www.cleanwisconsin.org/enviropedia.

Last updated: 6/29/2015