Green Infrastructure: Rain Gardens

What is a rain garden?

Rain gardens are a type of  bioretention systems that  help alleviate stormwater. Other types  include stormwater planters, green gutters, downspout planters, stormwater trees, and tree trenches.   Rain gardens, as well as other bioretention systems, capture rain water 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 rain water, 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.

Stream clouded with sediment
Diagram of Rain Garden (Rutgers University)

Why do we need rain gardens?

They are an environmentally friendly, easy way to capture rain water that otherwise may lead to flooding and increased pollution. As rain water flows across the landscape, which includes our yards, roof tops, patio, parking lots, etc., rain water picks up oil, pet waste, fertilizer, sediments and other pollutants. This polluted stormwater runoff is collected through storm drains and ultimately is discharged into our waterways.

Often homeowners are unaware of the effect that their stormwater runoff has on neighbors downhill. These systems are an important concept to consider when trying to alleviate flooding and erosion problems because they are a simple, environmentally friendly way to capture and treat rain water. These rain gardens are most successful when placed at the source of the issue. By installing a rain garden, you redirect the water from flooding your neighbor’s property into a garden that is both an attractive landscape feature that also allows for water to naturally soak into the ground.

What do rain gardens look like?

A simple rain garden may look like a flower garden or a nicely manicured landscape bed to the untrained eye, but these rain gardens serve the important role of absorbing 30% more water than the same size area of traditional lawn. There are various options, including downspout planters, stormwater planters, green gutters and more. For help in determining which option is best for you, please contact the Stony Brook-Millstone Watershed Association for assistance. Or for simple construction plans see the Rutgers Cooperative Extension Water Resources Program as well as the New Jersey Storm Water Best Management Practice Manual.

Stormwater Planter (Allison Jensen)
Downspout Planted (Philadelphia Green Streets)
Rain garden landscaped with shurbs (photo courtesy of NVSWCD)