Rain Gardens

The City of Des Moines Park and Recreation Department has been awarded a Resource Enhancement and Protection – Conservation Education Program (REAP/CEP) grant to create rain garden toolkits that will help homeowners, businesses, parks, and other groups get started on creating their own rain gardens. The goals of the project are as follows: To educate Iowans working with school grounds, businesses, city parks, and private residences about the benefits of rain gardens To inform Iowans of the resources available for the installation of rain gardens at businesses, school grounds, city parks, and private residences To increase the number of rain gardens planted at businesses, school grounds, city parks, and private residences throughout the state of Iowa To reduce nonpoint source pollution of Iowa’s waterways To build partnerships between organizations in the Greater Des Moines area that deal with water and water quality We are currently in the process of designing the toolkits and creating educational materials, and they will be made available to the public as soon as they are completed. General Information What is a rain garden? A rain garden is a shallow depression that is planted with native wetland or wet prairie wildflowers and grasses. Rain gardens are strategically located to capture runoff from impervious surfaces such as roofs, driveways, parking lots, and roads. These landscaping features help create beautiful green spaces while absorbing water, reducing runoff, protecting water quality and preventing flooding. How does a rain garden work? Rain gardens improve water quality by reducing and filtering runoff. The most polluted runoff occurs in the beginning of a rain shower as water rushes over hard surfaces. This water is the first to pick up sediments and pollutants. Rain gardens catch this water before it enters the storm drainage system. Sediments and pollutants settle out of the water and are absorbed by plant roots or treated through chemical processes in the soil. Why use rain gardens? The Nonpoint Source Work Group Executive Summary from the 2003 Iowa Water Summit says, “As a result of our landscape changes over time, stormwater does not infiltrate into the soil as it once did. Stormwater runs-off the landscape at an increased rate and volume, carrying with it the sediment, nutrients, and other compounds that constitute NPS pollution. More attention must be given to identifying technologies that reduce the amount of water and pollutants leaving the landscape.” Rain gardens -- depressed areas planted with hydrophilic native prairie plants -- address this very issue. Rain gardens help slow the flow of water over the surface of the landscape, and increase infiltration of water into the water table, all while filtering that water and reducing pollutants. The addition of rain gardens to our urban landscape could greatly reduce nonpoint source pollution in Iowa. Rain Gardens can: Help solve common drainage problems Reduce runoff and recharge groundwater supplies Keep sediments and pollutants out of streams Attract birds and butterflies Require less maintenance than grass lawns Reduce the amount of water pollution Rain Garden FAQ’s Q. Will a rain garden provide a breeding ground for mosquitoes? A. No. A properly designed rain garden will drain before mosquitoes can reproduce. It takes 10-14 days for a mosquito to develop from an egg into an adult. The rain gutters on your home are more likely to provide a better breeding ground than a rain garden. Q. Do all rain gardens have a wild and messy appearance? A. No. Rain gardens do have a natural rather than a manicured appearance, but they need not look messy. You can keep a rain garden looking neat and attractive by keeping the edges will defined. Taller plants often have a more unkempt appearance; so use shorter plants if you want your garden to have a cleaner look. Q. Would a rain garden cause flooding in my basement? A. Not if they are properly located and designed. Rain gardens should be located at least 10 feet away from buildings so that water does not drain along foundations. Also, your rain garden should drain away from rather than toward buildings. Q. Would I need to water my rain garden during dry periods? A. Maybe. How much water your rain garden needs will depend on the plants you choose. Native plants are adapted to a wide range of conditions, so they will only need watering in the driest seasons. Useful rain garden websites: www.mninter.net/~stack/rain/ www.raingardens.org www.dnr.state.wi.us/org/water/wm/nps/rg/RainGardenEducationKitContents.pdf www.clean-water.uwex.edu/pubs/raingarden/index.html www.greentopeka.com www.consciouschoice.com/environs/raingardens1405.html www.chicagowildernessmag.com/issues/spring2001/raingardens.html