Rain Gardens - the Natural Way to Manage Runoff

It's fairly common knowledge that surface runoff in urban areas can overload sewage and drainage systems; contribute to erosion; contribute to pollution of local water sources; and, of course flooding. Urban areas have lots of impervious surfaces (that don't soak up rainwater) like parking lots and roads, and the natural areas that would normally help manage excess water are diminished.

IU students going to class during the floods of 2008.
Photo credit: IU News Service

When I was living in Bloomington, IN and wading through swamped streets after periods of heavy rain on my way to class and work, I learned first-hand what kinds of problems poor drainage systems can cause! Although it was fun to canoe around Dunn Meadow and kayak down the rapids of the Jordan "River" for a couple days during the floods of 2008, many adjacent communities were declared federal emergency areas and are still dealing with the aftermath. The city was generally bogged down for periods of time after other heavy rains, which leads one to wonder how it could better manage its rain overflow problem.

Urban rain garden.
Photo credit: U. of Rhode Island

One solution can be rain gardens. Rain gardens have been a hot topic in the conservation world for the past few years. The EPA cites rain gardens as a successful way to manage runoff on their stormwater case studies. Essentially, they are a special sort of garden that is designed specifically to absorb water runoff - naturally. The water is stored in the soil. They're also more aesthetically pleasing than a drain, or a flooded sewer!

Rain gardens were first developed in residential areas in 1990 in Maryland. After a few years of studying their effectiveness, they proved to be "highly cost effective."

"Instead of a system of curbs, sidewalks, and gutters, which would have cost nearly $400,000, the planted drainage swales cost $100,000 to install. This was also much more cost effective than building BMP ponds that could handle 2-, 10-, and 100-year storm events.Flow monitoring done in later years showed that the rain gardens have resulted in a 75–80% reduction in stormwater runoff during a regular rainfall event (source)"

If you're interested in learning more about rain gardens, Indiana's Hamilton County SWCD will be hosting a Rain Garden Workshop on Feb. 28. Check out our calendar for details.