Can My Rain Garden Really Help Solve Flooding and Water Quality Problems?

Impervious surfaces such as roads, driveways and rooftops are constructed on top of "pervious" vegetated landscapes that once allowed rainwater to soak in. Even turfgrass lawns are quite impervious since their shallow, dense root systems don't function well to allow water to seep through.

Obviously, then, these impervious surfaces create stormwater runoff where there once was very little. Precipitation falling on these impervious surfaces runs off the land and often eventually ends up in our lowlands and river corridors where most of our flooding occurs. It also carries with it contaminants, such as fertilizers, road salts, oils, etc., which cloud and pollute our lakes and streams.

During a normal year, 80% of the precipitation falls during what is called a "2-year storm event". Depending on the design and size of your Rain Garden, you can hold a majority of the rain from a 2-year event on your property. Even if you only "manage" half of the runoff from a 2-year event, that is a substantial contribution to help reduce downstream water quality problems. Every little bit helps.

What if all landowners in subdivisions included rain gardens in their yards? Well, that would very substantially reduce the typical problems associated with urban runoff and flooding. Even where storm sewer systems are already installed, Rain Gardens can be a great benefit. They could also be built less expensively than the typically elaborate stormwater engineering plans. In many developments, stormwater is piped through storm sewers to large detention or retention ponds. These are costly engineered systems, usually planted to grass, that offers no benefits for wildlife or recreational purposes. They are costly and sometimes hazardous to maintain. With enough Rain Gardens in place, the size and costs for a typical urban stormwater system could be reduced in response to the reduced stormwater management needs.