Our staff test lake water.

What Impacts Our Lake Water Quality

Rain and melting snow that run over driveways, parking lots, streets, lawns, and farmland pick up and carry sediments and other contaminants. The pollutants in this water can end up in our lakes through the stormwater system.

Examples of pollutants that can end up in our lakes:

  • Sediment and nutrients washed from farmland and construction areas. These can cause lake and river waters to become murky and can gradually fill lakes and streambeds. It makes it hard for plants to grow and destroys aquatic habitats.
  • Oil, grease, pesticides, herbicides, cleaners, and toxic chemicals from motor vehicles. These can make animals and humans sick and destroy aquatic life.
  • Nutrients from lawn and garden fertilizers, and leaves. These can lead to blue-green algae blooms that can harm people and pets, and lead to the death of fish and other aquatic life.
  • Viruses, parasites and bacteria from waterfowl and pet waste, boat holding tank waste, and failing septic systems. These can lead to high bacteria counts, which may cause illness in people who swim in beach areas, and may also lead to possible contamination of drinking water.
  • Road salt used on roads and sidewalks in winter. Road salt washes into in our local lakes, streams, and aquifer-our drinking water source. Road salt is harmful to aquatic life and high sodium levels in drinking water can have harmful human health effects.
  • Get information on specific effects of phosphorus, chloride, and metals on our surface waters from the Healthy Dane water quality dashboard.

How to Protect our Lakes and the Environment

  • By law, wastewater produced indoors, like dirty mop water and laundry wastewater, must go into a drain indoors. That wastewater is then treated before being released into the environment. Do not dump it into storm sewers.
  • Limit use of pesticides, herbicides, and fertilizers on lawns and gardens. Follow label directions if using them. Sweep up and remove any granular fertilizer from driveways and sidewalks.
  • Keep pet waste, debris, trash, leaves, and grass clippings off of sidewalks and streets, and out of gutters, storm sewers, and lakes.
  • Wash your car in a location where the wastewater will soak into the ground and not run off into the gutter and storm sewer.
  • Make sure your roof drains go to a grass or gravel area and do not go directly to the street, driveway, or paved area that drains to the storm sewer.
  • If you see something going into the storm sewer or into a lake that has an unusual color or odor, or you see unusual floating objects in the water, report it to us by calling (608) 266-4821 or fill out an online report, below.

Report a Problem


Our Role In Protecting Our Lakes

We work to protect the water quality of our lakes, beaches, and streams by:

  • Monitoring and sampling water from area lakes, rivers, and streams to evaluate sources of potential pollution from discharge points and run-off from rain and melting snow.
  • Responding to reports when people see things going into the storm sewer or lake that have an unusual color or odor, or they see unusual floating objects in the water.
  • Testing for indicators of environmental concerns in our water, such as bacteria, toxins, and metals.
  • Testing water quality at area beaches and posting beach condition information from Memorial Day to Labor Day. (See Beach Water Quality page.)  
  • Regulating over 165 permitted sites for discharges of non-storm water to lakes Mendota, Monona, and Waubesa.

Resources