What is Runoff?
Snow melt or rainwater that does not soak into the ground and instead runs off hard surfaces
such as roofs, driveways, sidewalks, and compacted soils or washes off lawns and
steep slopes is called runoff. It is also referred to as stormwater. When runoff reaches
the lake, it can carry with it nutrients, eroded soil sediments, toxic materials, bacteria and
other pollutants that can be detrimental to water quality and fish and wildlife habitat.
Reducing runoff decreases the pollutants that can eventually reach the lake.
Managing stormwater on your property so it soaks into the ground (infiltrates) rather than
running off is the best way to reduce runoff and filter out pollutants before they reach the
lake. Hard or paved-over surfaces do not allow the absorption of water. Any green
space, including gardens, trees, shrubs or landscaping allows water to infiltrate slowly
down into the soil and roots.
The Wisconsin DNR calculated runoff volume from an undeveloped shoreland
lot compared to a large lake home (approximately 4,000 square feet of impervious
surfaces) on a lot entirely converted to lawn. They found up to a:
• 500% increase in runoff volume,
• a 700% increase in phosphorus washing into the lake, and
• a 900% increase in sediment flowing to the lake on the large home lot.