Earth Day 2018: Use Rain Gardens To Reduce Stormwater Runoff
- This article, contributed by Rob Linke, water resources engineer for the Kane County Division of Environmental and Water Resources, is part of a 15-part series of tips on how to make a positive environmental impact in Kane County.
Tip #9: Root for a Rain Garden
In an earlier article featured during the Kane County’s Countdown to Earth Day, we learned about stormwater runoff, its impact on water quality in Kane County’s streams, and what we can do to improve the water quality. The article featured 11 ways each of us can help to stop or reduce stormwater pollution.
One of those suggestions was to build a rain garden. Here’s a quick how-to.
What’s A Rain Garden?
A rain garden is a fancy name for a depressed, planted landscape feature that is specially designed and located on a property to capture stormwater runoff.
The goal of a rain garden is take the stormwater runoff directed to it and infiltrate as much of it into the ground as possible. These “stormwater gardens” are perfect for our residential properties as they keep our rainwater on our property instead of letting it run off into a nearby storm sewer or culvert and into our rivers and streams.
While rain gardens provide benefits such as infiltrating and filtering stormwater for water quality, they can supply many other benefits as well, including:
- Reducing potential for home flooding in our neighborhoods
- Eliminating standing water areas in our yards
- Reducing mosquito breeding areas (rain gardens are mosquito traps because they dry out before the mosquito eggs can hatch!)
- Recharging the groundwater supply (many of us get our water from groundwater wells)
- Creating local, micro-habitats for birds and butterflies
- Requiring less watering than traditional landscaping (native plants are drought tolerant)
- Enhancing sidewalk appeal
Rain gardens can range in size from a few dozen square feet to over a thousand square feet, and they can be built on virtually any type of property. However, they are best suited as a medium sized landscape feature, 100 square feet to 300 square feet in size, constructed on residential property.
While rain barrels are good stormwater options for residents and can hold between 50 and 90 gallons of stormwater, a medium size rain garden can handle more than 1,000 gallons of stormwater up to several times a week, so they are excellent features to keep our stormwater on-site and out of the storm sewer and downstream creek.
How To Build a Rain Garden
Rain gardens aren’t much harder to build than any other planted landscape area on your property, but they do require some additional planning and a few extra things depending on your property’s soil, slope and the amount of sunlight/shading.
Rain gardens are typically constructed by selecting an area down slope from your house (minimum 10 feet away; 20 to 30 feet is ideal) and excavating the footprint to a depth between 12 inches and 18 inches.
The underlying clay is removed, and the organic topsoil can either be reused and amended with sand. You can also use a special rain garden soil mix, which often is available from local landscape supply yards if requested.
The highly permeable, sandy-soil mix is then replaced in the excavation and the footprint is left “dished out” so that stormwater can temporarily pond in the rain garden to a maximum depth between 6 inches and 12 inches while it slowly infiltrates into the underlying soil following a rain storm.
The top of the rain garden is covered with a double-shredded hardwood mulch. A selection of native flowers and grasses are spaced out (12 inches to 18 inches on center) and planted into the soil.
Rain garden planting plans can range from very simple arrangements of two to four species of plants to very diverse planting arrangements and everything in between. This is where your creativity comes in!
There are MANY great resources on-line for homeowners interested in building their own rain garden. The University of Wisconsin-Extension offers a free guide to homeowners.
You can help treat stormwater and make your property look beautiful while doing it!