Stormwater Management


When water hits the ground during a rain or snow event, it begins an incredible journey through the A watershed is an area of land that drains water, and anything carried by that water, to a common location or larger body of water (e.g. the Chesapeake Bay) watershed in which it falls. The Chesapeake Bay Watershed encompasses over 64,000 sq. miles and drains portions of 6 states: Delaware, Maryland, New York, Pennsylvania, Virginia, and West Virginia. Every stream in Montgomery County eventually flows into larger rivers, all of which ultimately flow into the Chesapeake Bay.

Stormwater flowing through a culvert in a stream. Walking bridge in foreground.

In areas with a lot of impervious surfaces (roadways, parking lots, buildings), during storm events, larger than natural volumes of stormwater will rush into local streams. This can cause significant damage to habitat and other features within a stream. Stormwater Management is using techniques and practices to slow, soak in, or store stormwater to help reduce the amount of pollution entering our waterways. Stormwater management facilities reduce the volume and intensity of water that rushes into streams by providing an area for short-term storage of stormwater. The stormwater will slowly soak into the ground, mirroring a more natural environmental system.

Montgomery Parks is regulated by a National Pollutant Discharge Elimination System (NPDES) permit. This permit serves to regulate sources of stormwater pollution in the parkland. Parks has a strong commitment to environmental protection and stewardship of natural resources. Even prior to receiving an NPDES permit, Parks staff took steps to protect water resources and prevent pollution.

Under this permit, Parks staff are required to eliminate sources of pollution to local waters. This is accomplished through the implementation of the best management practices (BMPs) which are everyday practices that, when used, will help prevent the pollution of our waters.

Please see yearly Permit Reports and The NPDES Program in Parks documents at the right for more information.

Stream Restoration 

Stream section with restoration practices: armored bank, stones in middle of stream for habitat.

Montgomery Parks contain approximately 490 miles of streams that provide valuable wildlife habitat and recreational opportunities. As stewards of these aquatic resources, specialized staff applies and implements a wide variety of stream restoration practices that maximize ecological competency in Montgomery County’s most urbanized watersheds.

As stormwater leaves roadways, parking lots, rooftops, etc. via pipes and enters culverts and eventually streams, concentrated water erodes the areas beneath culverts and stream banks compromising water quality. Stream restoration practices utilize natural materials such as rock, logs, and native plants to help slow down the stormwater flow, promote infiltration, improve floodplain connectivity, and restore the bends, pools, and rocky areas found in stable streams. Specialized equipment is used to establish the shape of the stream and to bring in needed materials. Restoring streams also help protect adjacent properties and public infrastructure by reducing stream bank erosion and restoring aquatic ecosystems.

In addition to Parks, several entities regularly perform stream restoration projects on Parkland. They include the Montgomery County Department of Environmental Protection (DEP) and the Department of Transportation (DOT), Washington Suburban Sanitary Commission (WSSC), Maryland State Highway Administration (SHA), and others. Parks staff work closely with these agencies to minimize the impact of parkland during stream restoration.

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Last Updated: November 1, 2019