Rock Lake Project & Monitoring Report

Almost 20 years ago, Wisconsin legislators created the Nonpoint Source Water Pollution Abatement Program to control polluted surface runoff.  In 1995, Rock Lake joined a long list of lakes and streams with priority designation.  The Rock Lake Priority Lake Project targets the 12 square mile watershed area that drains to the lake, and focuses on land use activities that impact water quality.  The Project has access to technical support from various state and county agencies, as well as input from citizens who participate on the Citizens Advisory Committee.

Watershed/Lake Facts

A watershed is the area of land that drains its water into Rock Lake.  The water quality of Rock Lake is a direct reflection of the land use activities that occur in its watershed.  Rock Lake's watershed is 12 square miles and has a main inlet location on the south side.  The lake has a maximum depth of 56 feet, a surface area (including Marsh Lake) of 1,371 acres, and 6.2 miles of shoreline.

Rock Lake is classified a drainage lake.  This means the lake has both an inlet and an outlet, and the majority of the water in the lake is fed by stream drainage.

Drainage lakes tend to have variable water quality depending upon the amount of runoff and human related activity occurring in the watershed.  Watershed management is important in drainage lakes to control nutrient input and erosion, and protect water quality.

What is Nonpoint Source Pollution?

Nonpoint source pollution, also known as runoff, is water pollution that does not originate from a distinct source such as a pipe or diversion.  Rather, nonpoint source pollution is diffused across a wide area.  During periods of rainfall or snowmelt, runoff water washes over the surface of the land, eventually flowing into our lakes, rivers, streams, and groundwater.  Along the way, the runoff picks up a wide assortment of pollutants including:

  • Soil from construction sites, farm fields, eroded stream banks, and lakeshores.
  • Fertilizers and pesticides from croplands, lawns, golf courses, and parks.
  • Bacteria and nutrients from barnyards, manure spread on farm fields, and pet waste.
  • Toxic compounds like oil, lead, zinc, and other chemicals from streets, parking lots, and service stations.
  • Organic waste and nutrients from leaves and grass clippings left on city streets.

Although any one source of pollution may seem insignificant, together they can add up to a major problem.  Some of the effects on water include: lakes choked with weeds and algae, streams running brown with sediment (soil), and reduced populations of game fish and other aquatic life.  In addition, the rain and melting snow can soak into the ground, carrying bacteria, nitrates, and pesticides into the groundwater that supplies our drinking water.

Across Wisconsin, farmers, urban and rural residents, and local governments are taking steps to prevent nonpoint source pollution and clean up our waters.  The Jefferson County Land and Water Conservation Department is spearheading Rock Lake Priority Lake Project efforts in our area through a combination of state funding and local resources.  If you would like additional information on nonpoint source pollution and how you can help reduce it, please contact the Jefferson County Land and Water Conservation Department (920) 674-7121.