How Smarter Urban Planning Can Help the Chesapeake Bay
Better urban planning can help save our rivers and the Chesapeake Bay—by reducing this region’s future impervious surfaces by 20%. Here’s why.
As many Washingtonians know, the Chesapeake Bay needs help. Dead zones and algae blooms appear every summer which destroy aquatic life in the Bay and threaten fishing, swimming, and economic health. A major contributor to this problem is rainwater runoff from paved roads, parking lots, and roofs. These are called “impermeable surfaces”. In contrast, permeable (or pervious) surface is one through which liquids are able to pass.
Grassy fields, woodlands and farmlands are excellent examples of this: rainwater or snowmelt soaks into the ground, pollutants in the water are filtered naturally, and excess water travels underground to streams and eventually (in the Washington region) the Chesapeake Bay.Rainfall that falls on impervious surfaces like paved roads, parking lots and roofs “runs off” unfiltered making its way to the Chesapeake Bay—along with nitrogen and sulfur oxides from vehicle emissions, motor oil, and road salt residue.
Figure 1 – Map of impermeability throughout the region with overlaid jurisdictional boundaries and Metrorail system for reference. Note the concentrations of highly-impermeable surfaces in central D.C., and at other activity centers like Dulles.
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