Lakeside Stormwater Project:Background

Why are we so concerned about stormwater runoff?

Besides problems such runoff causes on residential properties, increased runoff due to development of the land is creating problems for area streams, including Amity Creek. Amity Creek is a DNR designated trout stream and is on the MPCA impaired streams list for turbidity (muddy water). Runoff enters storm sewers and flows directly into our streams and lakes untreated, carrying trash or pollutants with it. So we have a problem both with the amount of flow, and with the salt , nutrients, and pollutants in the water. In Duluth, MN and Superior, WI, the ultimate receiving bodies of water are the St. Louis River Estuary and Lake Superior.

Our homes, driveways, and buildings can generate a lot of stormwater runoff. This is the runoff calculation for Dr. Brady’s property for a 1 inch rainstorm:

	Length (ft)	Width (ft)	"Footprint" (sq. ft)	Runoff (gal.)
Driveway	12	60	720	449
Garage	24	26	624	389
Shop	24	30	780	486
House	26	32	832	518
Barn	26	52	1352	842
Total =			4308 sq. ft	2684 gal.

 

This means that 2684 gallons of water falls on the more than 4000 square feet of hard (we call it "impervious") surfaces that were built on the property from a 1" rainstorm. Before the property was developed this water would mostly have soaked into the ground and very slowly seeped into a local stream or wetland. If it all runs off the property, it can cause problems as it combines with runoff from other properties. The greater the percentage of impervious surface in the watershed, the greater are the impacts on downstream water bodies, and the more expensive it is to fix the problems.