Reduce Stormwater Runoff With a Rain Garden

You can single-handedly curb your city's pollution by building a lovely, native rain garden.

| March/April 2007


A blue flag iris (Iris virginica shrevei) is a lovely sign of spring.

Booming urban growth, and the concrete that comes with it, has pushed storm drainage to its limits. Most cities channel rain overflow to holding ponds via drains and culverts, which then empty into fresh-water supplies. These manmade systems are designed to move water quickly, but several factors make all this drainage a problem. First, our urban areas produce a lot of runoff: An impervious surface such as a parking lot or rooftop generates nine times more runoff than a wooded area of the same size, according to the Environmental Protection Agency. Second, pollutants such as motor oil, fertilizers, pesticides and debris also are washed down storm drains, accumulating and becoming more concentrated as they enter streams and ponds. This poisonous runoff pollutes drinking water supplies, harms fish and wildlife, kills native vegetation, and makes recreational areas unsafe.

Stop the cycle

In an effort to restore natural drainage patterns to cities across the country, many people are planting rain gardens. Planted in depressions in yards and along roadsides, rain gardens (also called “bioretention” areas) are designed to catch and divert runoff into the ground before it reaches storm drains. Rain gardens include plants, usually natives, that help percolate rain back through the soil. By doing so, they also filter many contaminants.

Municipalities and watertreatment districts nationwide are promoting or subsidizing rain gardens. In Kansas City, where violent storms and flash floods are the norm, city organizers recently launched the 10,000 Rain Gardens project to address storm-drainage issues. This volunteer initiative includes an educational website and how-to classes, links with landscape professionals and hundreds of official participants.

Scott Cahail, environmental manager of Kansas City’s Water Services, believes the initiative does more than prevent flooding. “We should value water as a resource, not see it as a nuisance,” he says. When people add rain gardens to their landscapes, they see the cycle of water conservation. Plus, native plants or flowers attract bees, birds and butterflies. “And on the practical side, it eliminates a patch of grass that needs mowing!” Cahail says. He estimates the cost of building a rain garden at $10 per square foot or even less—the environmental benefit is priceless.

Build a Rain Garden in 10 Steps

elderberry, echinacea, bee hive


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