Using Spectacular Wetland Plantings to Reduce Runoff
From Plants & Gardens News Volume 19, Number 1 (Spring 2004) by Janet Marinelli

I used to hate rainy days. The drama of each passing storm escaped me. I'd sulk inside, waiting for the leaden clouds to lift. Then one day, as a nor'easter lashed our Shelter Island, New York, home, my husband, Don, and I watched the storm water come gushing down our gutters, creating a gully as it carried eroded soil down the driveway. We decided to figure out how much water rolls off our roof each year, and where it all goes.

Like most people, Don and I didn't think a lot about the earth's hydrological cycle, which supports every terrestrial creature, from human being to towering tree, in the form of rain, fog drip, and snow. Over the ages this precipitation has etched a vast web of watersheds into the planet's surface. However, our huge and costly storm-water infrastructure subverts nature's plumbing system. Rainfall is immediately whooshed from our roofs to gutters and downspouts and channeled by concrete curbs to storm drains and pipes, sometimes in destructive torrents.

In a natural landscape—a forest, say—there's generally very little runoff. The soil and its dense cover of leaf litter and vegetation act as a sponge, absorbing most precipitation. But because we've replaced so much natural groundcover with impervious surfaces, rainfall no longer soaks into the soil as readily as it once did. As a result, huge volumes of runoff flow from countless roofs and compacted lawns down driveways and roads to storm sewers, carrying pesticides, motor oil, and other pollutants to nearby streams and rivers, fouling surface waters and destroying aquatic life through sheer physical force. The U.S. Environmental Protection Agency estimates that a typical city block generates nine times more runoff than a woodland area of the same size. According to the EPA, storm-water runoff is the leading threat to the nation's estuaries and the third-largest problem facing lakes.

After a few minor calculations, Don and I determined that more than 20 thousand gallons of water pour off our roof each year. (To figure out how much rain runs off your roof, use the formula in Resources.) We wanted to find a natural, low-tech way to dissipate the runoff and encourage it to seep into the soil. We decided to create a rain garden by directing the storm water from our downspouts into a low area we excavated and filled with lovely wetland wildflowers.

Construct your own rain garden to enhance Lake Champlain and the fisheries!