What Is A Rain Garden?
. . . . and how does it work?
Excerpted from: Green Infrastructure
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As water runs down roofs, driveways and patios and off other impervious surfaces,
it picks up pollutants as it flows directly into streams, wetlands, lakes and groundwater aquifers.
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Stormwater runoff has become the number 1 source of residential pollution for waterways. It
increases potential flooding. Some municipalities have responded, installing rain gardens, a type
of green infrastructure, in public and commercial spaces to slow down and treat the water before
it enters streams, wetlands, lakes and groundwater aquifers.
Rain gardens are a type of water capture feature in landscaping that helps slow and absorb
runoff from storms. Other types of naturalized bio-retention methods include
storm water planters, green gutters, downspout planters, storm water trees, and tree trenches.
The word “bio-retention” speaks to the process of filtering contaminants and sedimentation
from storm water runoff.
Rain gardens, as well as other bio-retention systems, capture rainwater before it can flood your
property or flow into a storm drain, eventually reaching swollen streams. They range in scope
from an industrial size of several thousand-square-feet to a residential size of one hundred-square-feet
or less.
Rain gardens recreate the natural function of the land, which includes; capturing rainwater,
filtering out pollutants, and recharging groundwater. They can be constructed as simply as
digging a shallow depression and filling it with native plants and soil amended with sand.
Rain gardens are an easy way to capture rainwater that otherwise may lead to flooding and
increased pollution. This is because as rainwater flows across our yards, patios, parking lots,
and other hard surfaces, the water picks up oil, pet waste, fertilizer, sediments, and other pollutants.
This polluted storm water runoff courses into storm drains and eventually dumps into our stream,
rivers and other waterways.
No mowing needed. Rain gardens should be trimmed, mulched, and maintained to prevent
clogging, but you’ll never have to mow.
Pollinator friendly. Native plants in rain gardens will bring birds, butterflies, and bees fluttering
into your lawn. .
Groundwater recharge. Rain gardens help recharge depleted groundwater sources. Water
captured by a rain garden drains back into the soil, which replenishes local aquifers.
No fertilizer, herbicide, or pesticide required. Native plants are adapted to your region and soil
type, so they won’t need fertilizers or harsh chemicals.
Water pollution protection. Rain gardens divert rainwater away from storm sewers, reducing
the load on the sewer system. Less contaminated water gushes into rivers and lakes and harms aquatic
wildlife. .
Benefits of rain gardens can include a healthier and happier landscape in addition to its bio-retention
properties. Utilizing native plants in a rain garden creates essential habitat for beneficial animals and
insects. Local pollinators make use of plants that can be found in many rain gardens, which in turn
helps the natural food chain and local agriculture.
Retaining water in the ground also helps to build soil health with microbes and mycorrhizae.
Healthy soil can capture and retain carbon more effectively than dry or monocultured land can. A
diversity of plants with healthy soils will do wonders for water quality and unseen natural life that
takes place in your landscape.
Not only do rain gardens reduce pollution and flooding while contributing to groundwater resources,
but they can also be a visually attractive feature. One of the best reasons to install a rain garden is that,
unlike some other methods, this cost-effective bio-retention powerhouse looks great while providing a
wide variety of other untold benefits.
University of Wisconsin: Rain Gardens-Homeownes Guide
Dane County: How To Build A Rain Garden
UW-Extension: Rain Gardens-A Way To Improve Water Quality
Rain Garden Plant List