Rain Garden

What is a rain garden?
A rain garden is a garden with a shallow depression which is strategically located on a property to capture stormwater runoff from impervious surfaces, such as rooftops, patios, driveways, and parking lots, before it enters the storm water system. The water is held by the garden and allowed to slowly infiltrate the soil. The soil and plant roots use natural processes to improve water quality by filtering pollutants, the overall amount of stormwater runoff is reduced, and the groundwater supply is recharged.

Why is stormwater a problem?
Most modern American cities are built in such a way that when it rains, all of the water is directed immediately into storm sewers via gutters, curbs, and ditches and then out into nearby creeks and streams. On its way to the stormwater system, the rain water picks up pollutants such as motor oil, grease, pet waste, fertilizers from lawns, and other toxic substances. The water then rushes out all at once from storm sewers, severely eroding the banks of the creeks it is directed into and bringing all of the pollutants from the city into the water. This is called non-point source pollution.

What is an impervious surface?
An impervious surface is any surface that doesn’t allow rain water to penetrate into the soil. This includes roofs, roads, cement or gravel driveways, sidewalks, and most lawns (because the shallow, dense root system acts almost like cement). Impervious surfaces contribute to increased amounts of stormwater runoff, increased non-point water pollution, and the urban heat island effect.

What is non-point source water pollution?
Point source pollution is that which is sent directly into streams, creeks, and rivers via pipes. Non-point source pollution then is any other pollution that makes its way into these bodies of water, usually via stormwater runoff. That includes sediment (from erosion and agriculture), pesticides, fertilizer, pet waste, agricultural runoff, salt from the roads in winter, motor oil, grease, and litter.

How else can I reduce impervious surface on my property?
Replace your concrete or gravel driveway with the kind that has two strips of concrete just for your tires, plant more native plant gardens in your yard, reduce the overall amount of concrete on your property, plant rain gardens to collect rain water from your roof!

Why native plants?
Native plants are ideal for landscaping for many reasons. Because they have adapted to our climate over many years, they don’t need chemicals to help them grow, they can tolerate our cold winters and hot summers winter, they have very deep roots which allow them to be more drought resistant, they have developed defenses against harmful native insects, and can serve as habitats for native wildlife (consider planting for butterflies, hummingbirds, or songbirds!). The deep roots of native plants also makes them ideal for rain gardens because they create channels in the soil which allow water to soak in quickly.