Project reduces rainwater runoff problems

Raingardens help to ease erosion and pollution caused by spring rainstorms.
Thursday, April 19, 2007 | 12:00 a.m. CDT; updated 12:35 a.m. CDT, Sunday, July 20, 2008

April showers bring more than May flowers to Columbia residents suffering from water drainage problems.

Winter snows have yielded to spring rainstorms in mid-Missouri, which often threaten to overload drainage systems, erode property and pollute nearby streams with chemical runoff. Scott Hamilton of Show-Me Clean Streams has a primitive, but practical, solution to help curb these problems: Dig a hole in your yard and fill it with native plants.

They’re called raingardens, and about 25 people attended Hamilton’s presentation at MU’s Bradford Research and Extension Center recently to watch Hamilton’s presentation on how to build one. The design is simple — a shallow depression to collect water and different kinds of native plants for stability and aesthetics — but the benefits for landowners and the local environment can be many.

As Columbia grows, more and more open water-absorbing land is covered by impermeable surfaces like roads, roofs and driveways. Rain that would have fallen on grass and been absorbed into the earth instead hits a solid barrier. It then flows over the top of the surface, picking up lawn care chemicals, oil, animal waste and many other harmful substances that are eventually carried unfiltered into local streams.

“Anything we drop on pavement here usually ends up in the Hinkson watershed, which makes me very angry,” Hamilton said.

Pollutants deposited in streams can kill fish and insects, disrupt reproductive cycles, and create cloudy, algae-filled water. A raingarden is engineered to collect the “first flush” — the initial half inch of runoff that contains most of the collected pollutants, easing the stress on man-made drainage systems and filtering water before it re-enters streams.

“A 10-foot-by-10-foot area is probably enough to detain the initial half inch from an average-sized roof,” Hamilton explained to listeners at the presentation.

Installing a raingarden “is about the same amount of effort as putting in a raised flower bed,” Hamilton said.

MU seniors Krista Marshall and Sarah Pennington, who recently built a raingarden at the Bradford Center as part of a plant taxonomy class, consider it a “weekend project” once you have the supplies assembled.

Using native plants in the raingarden can keep maintenance down.

“Native plants are adapted to flooding and drought,” Marshall said. “Planting natives will allow you to eventually let it go. If you want, you can leave it be.”

Vigilant weeding is necessary for the first year after installation, but a native raingarden should become self-sustaining afterward.

“Anytime you can avoid using exotic plants, you should,” said Marshall, who is a biology major. “Keeping the ecosystem natural is important. You don’t know what the kind of diseases and insects you’re introducing with exotic plants.”

Part of that ecosystem is animal life. Standing water in the pool can attract squirrels, crayfish and rabbits. Minnows purchased from a bait shop will eat mosquito larvae before they hatch.

A lush environment like a raingarden could become the centerpiece of a yard or a neighborhood if undertaken as a community project.

“It would be great if we could get a community program going here,” Marshall said.

City officials in Kansas City agreed to do just that in 2005, launching an initiative called “10,000 Rain Gardens.” The project is aimed at relieving the city’s outdated drainage system with voluntary raingarden construction on a large scale.

“I’ve considered approaching (Columbia) city officials with a similar project,” Hamilton said.

The city is installing several raingardens downtown later this spring. It’s a small step, but the exposure from a high profile location and the Hinkson Creek Watershed Restoration Project’s willingness to donate up to $100 per raingarden construction project in the area might just be enough to get the ball rolling.

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