Rain Gardens an Elegant Way to Handle Storm Water

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Facilities & Services Rain Garden sketch

Sandy Mason's UI Extension column on Rain Gardens

Wisconsin DNR Rain Gardens How-to Manual for Homeowners (pdf file)

In a vegetable garden, you grow vegetables. In a flower garden, you grow flowers. In a rain garden you . . . . Well, unlike these others, the purpose of a rain garden isn’t limited to what grows in it. A rain garden is actually a landscape feature that functions as a small-scale, temporary wetland.

A rain garden typically consists of a shallow depression that is planted with shrubs, flowers, and grasses that are native to the region where it is located. A rain garden may be designed to receive water from a downspout or sump pump, or it may be located to intercept water that runs off of a parking lot or other impermeable surface.

Like a natural wetland, a rain garden provides important ecological services. Chief among these, it reduces the amount of water that enters streams via storm drains during and immediately following rain showers. In this way, a rain garden helps to alleviate flooding and cut down on the amount of silt and pollution that washes into our waterways. Water that is held back in a rain garden infiltrates the soil more effectively than water that runs over a lawn, and thus it can also help to recharge groundwater locally.

Also like a natural wetland, a well-designed rain garden is a pleasure to look at, and it provides a bit of wildlife habitat, albeit on a small scale. During the growing season native flowers used in a rain garden can be a magnet for butterflies and other beneficial insects. Over the winter the seeds from those flowers and the berries from shrubs can provide food to attract birds.

I should emphasize that while a rain garden functions like a wetland, it is not a pond. A rain garden should dry up following precipitation as the water it holds filters into the soil.

If you would like to see a really super rain garden in the making, check out the project on the U of I campus just south of Allen Hall on Dorner Drive. There, students enrolled in a Natural Resources and Environmental Sciences internship class are busy actually constructing a rain garden. They’re implementing a design that was produced by students from another class this past Spring. Beyond retaining and purifying stormwater, this particular rain garden is intended to alleviate ponding around a substantial red oak tree on the site, and to prevent flooding on heavily used adjacent sidewalks. Construction of the rain garden is being funded by U of I Facilities & Services in conjunction with the Environmental Council as part of a broader effort to develop and showcase sustainable practices on campus.

If you are interested in creating a rain garden of your own, you may want to start with some of the links at the Environmental Almanac website. These include a how-to column by U of I Extension educator Sandy Mason and a more detailed online manual for homeowners.

Whether at home or in larger landscapes, if your goal is to reduce storm runoff, rain gardens are an elegant, low tech, low cost, environmental solution.