What happens to a drop of rain when it falls onto the ground? It may land on a tree and evaporate; it may land on a farm field and soak into the soil; or it may land on a rooftop, driveway or road and travel down the street into a storm drain or stream.
Precipitation in an urban or suburban area that does not evaporate or soak into the ground but instead runs across the land and into the nearest waterway is considered stormwater runoff. Increased development across the watershed has made stormwater runoff (also called polluted runoff) the fastest growing source of pollution to the Chesapeake Bay.
As stormwater flows across streets, sidewalks, lawns and golf courses, it can pick up harmful pollutants and push them into storm drains, rivers and streams. These pollutants can include lawn and garden fertilizers, pet waste, sand and sediment, chemical contaminants and litter.
Stormwater runoff can cause a number of environmental problems:
Stormwater runoff can also lead to flooding in urban and suburban areas.
Forests, wetlands and other vegetated areas can trap water and pollutants, slowing the flow of stormwater runoff. But when urban and suburban development increases, builders often remove these natural buffers to make way for the impervious surfaces that encourage stormwater to flow freely into local waterways.
Impervious surfaces are paved or hardened surfaces that do not allow water to pass through. Roads, rooftops, sidewalks, pools, patios and parking lots are all impervious surfaces.
Impervious surfaces can cause a number of environmental problems:
According to the U.S. Environmental Protection Agency (EPA), the presence of roads, rooftops and other impervious surfaces in urban areas means a typical city block generates more than five times more runoff than a forested area of the same size.
Impervious surface data are used to measure the rate of development across the watershed and to identify high-growth areas and patterns of sprawling development. Between 1990 and 2007, impervious surfaces associated with growth in single-family homes are estimated to have increased about 34 percent, while the watershed’s population increased by 18 percent. This indicates that our personal footprint on the landscape is growing.
Stormwater runoff is the fastest growing source of pollution to the Chesapeake Bay. According to the Chesapeake Bay Program’s Watershed Model, stormwater contributes 16 percent of nitrogen loads, 16 percent of phosphorous loads and 25 percent of sediment loads to the Bay.
For Chesapeake Bay restoration to be a success, we all must do our part. Our everyday actions can have a big impact on the Bay. By making simple changes in our lives, each one of us can take part in restoring the Bay and its rivers for future generations to enjoy.
To lessen the impacts of stormwater runoff on the Bay, consider reducing the amount of precipitation that can run off of your property. Install a green roof, rain garden or rain barrel to capture and absorb rainfall; use porous surfaces like gravel or pavers in place of asphalt or concrete; and redirect home downspouts onto grass or gravel rather than paved driveways or sidewalks. You can also follow safe and legal disposal methods of paint, motor oil and other household chemicals to make sure they do not run into rivers and streams.
Green infrastructure can save money, clean our air and water, and offer residents social gains.
Cost-effective and common-sense projects could improve the region’s environment and economy.
Homeowners can play a big part in reducing pollution and improving water quality.
The Green Streets, Green Jobs, Green Towns initiative supports grassroots-level green development.
Nutrient pollution and floating trash posed problems for the Harbor in 2012.
Computer simulations of pollution controls implemented between July 2009 and June 2013, calibrated using monitoring data, indicate that nitrogen loads to the Bay would have decreased 20.28 million pounds to 262.38 million*.
Computer simulations of pollution controls implemented between July 2009 and June 2013, calibrated using monitoring data, indicate that phosphorus loads to the Bay would have decreased 2.04 million pounds to 17.19 million*.
Computer simulations of pollution controls implemented between July 2009 and June 2013, calibrated using monitoring data, indicate that sediment loads to the Bay would have decreased 497 million pounds to 8,178 million*.
Publication date: May 27, 2009 | Type of document: Policy Memorandum | Download: Electronic Version
Letter from Chesapeake Bay Leadership to Congress to Reduce Polluted Runoff from Federal Highways
Publication date: December 03, 2001 | Type of document: Directive | Download: Electronic Version
Increased population and development within the watershed have created projections regarding urban and suburban growth and the increase of imperviousness in the watershed, managing stormwater runoff is an important activity for reducing…
Publication date: August 01, 1987 | Type of document: Report | Download: Electronic Version
This is a report on vegetative filter strips for agricultural runoff treatment