Seal of Dane County County of Dane
Dane County Land & Water Resources Department

Dane County Urges Actions to Reduce Impact of Spring Thaw and Spring Rains

March 31, 2005
Sue Jones (267-0118), Dick Lathrop (261-7593)
Land & Water Resources

Where did all that snow go? Runoff of agricultural manure is not the only water quality issue during spring snowmelt and spring rainstorms. Snowmelt and rainfall runoff in our neighborhoods with the sediments and pollutants it carries also threatens lake and stream quality. Each of us should take steps to reduce impacts of urban runoff, according to Wisconsin DNR Limnologist Dick Lathrop. "While the ground is frozen, all the nutrients in leftover leaves, garden debris and yard waste are stopped in place. In spring, the nutrient-laden melt water runs to the nearest storm drain and into the nearest lake or stream," says Lathrop. Melt water contains dissolved materials including those nutrients that contribute to algal blooms. Melt water tends to run slowly, picking up speed during the day as it warms. The silt and organic particles like leaves moved to the lakes and streams by the faster flow carry nutrients to the lakes, but also contribute directly to sediment buildup and shallowing of the water. Sediments provide habitat for invasive plants and other aggressive invaders, which damage native vegetation, fish and other elements that maintain the health of a lake. "Salt is also an issue. We're raising salt levels in groundwater and in lakes. Although it's not at a toxic level, chloride levels are getting higher. It's the constant loading to groundwater that could be a serious issue in 100 years," says Lathrop. How can nonpoint pollution from snowmelt and spring rains be reduced? "To help, you can remove street gutter material and compost it for use on flowerbeds rather than let it gather in the gutters to be taken down to a storm drain headed for the lakes. Street sweeping stops for the winter and leaf material in the gutters will leach its materials and go straight into the waterways if not removed from the gutter," says Lathrop. For more information on what you can to do to help the lakes and streams in your area, visit or # # #