Suburban and urban areas are the fastest growing source of stormwater runoff affecting the health of the Chesapeake Bay. Homes, driveways, sidewalks and parking lots prevent rainwater from filtering into the soil before reaching storm drains and streams. Runoff from storms picks up many pollutants like pet wastes from lawns and vehicle fluids from driveways. The rushing water erodes stream banks and carries sediments. These sediments and pollutants hurt water quality and harm wildlife. For towns that get drinking water from lakes and rivers, the pollutants can be very costly to remove. Plants and soils do a remarkable job of cleaning water and can be used in our landscapes to reduce runoff and provide clean water.
Pervious surfaces allow water to pass through and filter into the ground. For driveways and patios try pervious pavers that leave spaces filled with gravel or grass. Sidewalks and driveways can be made with pervious concrete or pervious asphalt which have pores that allow water to drain through and filter into the soils below.
Even a healthy looking lawn can act like an impervious surface if the soils below it are compacted. Avoid compacting soils by establishing mulch or gravel walkways through heavily trafficked areas. Improve the health of your soil by adding compost. Create gardens where the soil can be more easily worked and where deep-rooted plants can break up compacted soils.
Rain gardens capture and filter stormwater runoff from roofs, driveways and parking areas. Usually they are shaped like a saucer. Rain gardens fill with rainwater that drains slowly over a few hours or a day. They are planted with plants that can tolerate being flooded for short periods of time but that also tolerate dry soils. The size of a rain garden depends on how much area it is collecting water from and how much rainfall your region receives on average.
A tree's leaves intercept rain as it falls and the roots take up water from the soil. The tree roots also hold soil in place helping to prevent erosion. Trees absorb many air pollutants making the air and rainwater less polluted.
Article by Sylvan Kaufman. Dr. Kaufman is a writer of popular scientific and gardening articles. She is also an ecological consultant.