Overview
A rain garden is a shallow, landscaped depression planted with native flowering perennials and other native vegetation that is naturally adapted to wet conditions. Rain gardens are designed to receive and absorb stormwater runoff from impervious surfaces like driveways, sidewalks, parking lots, and rooftops.
Rain gardens allow stormwater to slowly soak into the ground, reducing the amount of runoff flowing into storm drains and surface waters like streams, rivers, and lakes. A rain garden built below a downspout on a typical quarter acre residential lot will reduce the annual runoff from that lot by 25 percent! 1
Benefits
While an individual rain garden may seem like a small thing, collectively they can produce substantial neighborhood and environmental benefits, including:
- Increasing the amount of water that filters into the ground, which recharges local and regional aquifers;
- Helping protect communities from flooding and drainage problems;
- Helping protect streams and lakes from pollutants carried by urban stormwater – e.g. lawn fertilizers and pesticides, oil and other fluids that leak from cars, and numerous harmful substances that wash off roofs and paved areas;
- Enhancing the beauty of yards and neighborhoods;
- Providing valuable food and shelter for birds, butterflies, and many beneficial insects. 2
Cost Considerations
Rain garden installations average $3 to $5 per square foot depending on soil condition/density and types of plants used. If a landscaper does the work, costs are approximately $12 to $15 per square foot. If planned and designed properly, a rain garden is likely to retain its effectiveness for over 20 years. 3
Mosquitoes
Mosquitoes typically need 7 to 12 days to lay and hatch eggs. A properly installed rain garden will have standing water for no more than a few hours after most storms and will therefore not be a breeding ground for mosquitoes. Also, rain gardens attract dragonflies which eat mosquitoes! 4
Simple Guidelines for Homeowners
The Wisconsin Department of Natural Resources has developed a rain garden manual for homeowners which can be downloaded for free at the link below. The manual offers detailed guidelines, sample designs, and plant lists.
Download the manual for free.
Advanced Guidelines
Applied Ecological Services has developed a technical manual that is more advanced than the homeowner's guide above. AES's publication can be downloaded for free at the link below. Note that the manual includes many color photos of sample designs which may be of interest to novices and professionals alike.
Download the manual for free.
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