What if rain gardens were as common as lawns? The image of rain gardens lining the street, immediately below, is an inspiring one … what if all streets were lined with rain gardens? Think of the benefit to water quality and life.
Photo Source: Capitol Area Watershed District, St.Paul, MN _ www.capitolregionwd.org/our-work/monitoring-and-mapping/bmp/
Rain gardens are designed to capture rain water and prevent the rapid release of excess stormwater into municipal water systems. A well placed rain garden reduces runoff and flooding, and filters pollutants carried in stormwater runoff. Along with the municipal benefits and the conservation of a valuable natural resource, rain gardens create excellent habitat for birds and butterflies. Amazing. So why aren’t they as common as lawns?
First, lets look at some basic misconceptions…
Misconception #1: Standing water in rain gardens can breed mosquitoes.
Rain gardens are designed to drain in less than 24 to 48 hours – not enough time to create a mosquito breeding environment. Rain gardens in areas with better soil drainage will drain even faster – down to 12 hours.
Misconception #2: Only plants that require wet growing conditions will thrive in a rain garden.
A rain garden is not a pond. It is dry most of the time. A variety of plants that tolerate a wide range of conditions work best. Plants located in the lower part of a rain garden may stand in water on occasion, but they must also tolerate long periods of drought. Plants on the sides of the garden will vary between occasionally wet soil and dry conditions. Plants at the highest points may never experience standing water.
Misconception #3: Rain gardens look wild and weedy.
Gardens look weedy when: plants grow too tall and flop over; too many plant varieties are used; plants are not in distinct groups; or gardens don’t have defined edges. By using plants in scale with the garden size, placing taller plants in the middle of the garden, maintaining well-defined edges, and creating attractive plant groups, rain gardens can make beautiful additions to a landscape. (see photo, above)
Why do we need rain gardens?
As urban communities expand (replacing forests and agricultural land) the increase of solid impervious surfaces becomes more problematic. The solid surfaces that make up our cities create a rush of water during rain storms, known as ‘stormwater runoff.’ The massive volume of stormwater runoff from roofs, parking lots and roads increases flooding and carries pollutants from streets, parking lots and lawns into local streams and lakes. This leads to costly municipal improvements in stormwater treatment structures.
Photo – US Geological Survey
Photo – US Geological Survey
With larger or more frequent storms, increased water flows can contain more water than a municipal water system can handle. In some municipalities, excess unfiltered stormwater (overflow) that can’t be dealt with is let directly into lakes. Large stormwater flows also carry debris, clogging storm sewer exits and contributing to flooding. Refuse that runs with the storm water will also pollute the end catch basin, whether a drainage ditch or trout stream. Lawn pesticides and fertilizers wash off with the rain water, causing nutrient loading, decreased oxygen levels and subsequent algal blooms within our local lakes and rivers. Decreased oxygen levels have proven to produce declines in fish populations and overall decreases in aquatic species diversity.
A rain garden is a personal contribution to clean water in your community
To reduce stormwater runoff from your property look at your property and identify where the water goes. A rain garden should be positioned near a runoff source like a downspout, driveway or sump pump to capture rainwater runoff and stop the water from reaching the sewer system.
An individual rain garden may seem like a small thing, but collectively they produce substantial neighborhood and community environmental benefits. Rain gardens improve water quality – they can reduce the amount of pollution reaching creeks and streams by up to 30%.
Rain garden in Leominster, MA – Photo Credit – MA Watershed Coalition
Resources to get started
The construction of a rain garden is a task that an average homeowner can undertake with a bit of guidance. Good sources of information on rain gardens is available through a Wisconsin DNR and UW Extension publication developed by Roger Bannerman: Rain Gardens: A how-to manual for homeowners (PDF).
One of the keys to a successful rain garden is chosing plants that not only soak up excess water, but are also drought and heat tolerant. Midwestern plants that grow in clay soils fit that criteria.
Prairie Nursery offers a selection of pre-planned rain gardens in various sizes and for various soil conditions. Gardens come with planting instructions and layout.
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Benefits of a Rain Garden
• Filter runoff pollution
• Recharge local groundwater
• Improve water quality
• Protect streams and lakes from pollutants carried by
urban stormwater – lawn fertilizers and pesticides, oil and
other fluids that leak from cars, and numerous
harmful substances that wash off roofs and
paved areas
• Remove standing water in your yard
• Reduce mosquito breeding
• Protect communities from flooding and drainage problems
• Create habitat for birds, butterflies and beneficial insects
• Create drought tolerant green areas
• Beautify yards, neighborhoods and parks