Rain Gardens Help Treat Stormwater Runoff

July 9, 2003

Larry Crawford, associate director for programs and planning with Prince George's County (Md.) Department of Environmental Resources, generally is credited with designing and helping popularize rain gardens, reports Associated Press writer Dean Fosdick.

He also helped move them from industrial and commercial applications to residential landscape use, and they're being grown nationwide.

"My background is biology and chemistry," Crawford told Fosdick. "I've done a lot of work in the wastewater field. We used soil there to clean wastewater, so I thought I'd like to transfer the idea to the stormwater business."

The groundwork to do so included doing more research, while developing new standards and specifications. He also helped design a manual on the subject and then began working toward moving rain gardens from factory sites to home sites – all about a decade ago.

"Bioremediation sounded kind of stiff, so we came up with rain garden, because that's what they do. They're little gardens that treat rain."

Stormwater run-off is the nation's No. 1 source of water pollution, according to EPA.

Pinpointing polluters is all but impossible because contaminated runoff is caused by many activities occurring on many different kinds of landscapes: agriculture, grazing, mining, forestry, construction, urban litter, deposits from air pollution, and poorly maintained septic systems.

"Individual actions such as pouring used motor oil down a storm drain or applying chemicals to a suburban lawn cause a further degradation of water quality," according to EPA.

This results in algal blooms choking waterways, fish kills, shellfish restrictions, beach closings, and an increase in waterborne diseases.

One of the best ways to intercept runoff is by building rain gardens near downspouts, curbs, sidewalks, driveways and parking lots. Those surfaces often are the fastest routes for impure water to flow into otherwise clear ponds and streams.

Designers recommend building one or more rain gardens if you frequently see standing water or erosion in your yard, if you're concerned about the amount and quality of water flowing from your property and if you want to attract more wildlife.

"Landscape architects understand that all we're doing is adding a cleansing function, making it work for us to control the natural process that goes on in the soil to clean water," Crawford said.

Most of the clean-up work is done by the kinds of sediments you have underlying the gardens, the mulch you layer around the top and the root systems of the plants you choose.

Biochemical activity helps the toxins that wash down in the so-called "first flush" from a steady rain. The pollutants transform themselves into harmless compounds like phosphorous and nitrogen. The roots take up the nutrients.

Source: The Associated Press

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