View of a natural filtration feature with native plantings and twin culverts alongside a road.

Sylvan Shores Stormwater Management System


Built in the 1940s along the South River of the Chesapeake Bay, the 250-home Sylvan Shores community lacked a stormwater management system. During storm events, water pooled in low spots, residences regularly flooded, and untreated runoff flowed directly into the bay. The runoff was especially concerning because Sylvan Shores lies within the Chesapeake Bay Critical Area, and the nitrogen and phosphorus in untreated runoff can lead to algae blooms, causing significant threats to aquatic life.

Recognizing that the Maryland Department of Natural Resources (DNR) had grant funding available, Gannett Fleming worked hand-in-hand with state, county, and local officials to develop and submit a conceptual plan to manage the community’s stormwater. This plan was in strategic alignment with state goals for pollution reduction. As a result, Sylvan Shores was awarded a $1.87 million Bay Restoration Fund grant for the system’s design and construction.

What We Did

The team’s design used best management practices to slow and treat runoff before it reaches the bay. A visual survey of the community helped the team employ sand filters, grass swales, and micro-bioretention structures to treat runoff naturally where it collected. To maximize treatment, the design uses every bit of available land between backyards, along roadsides, and in flood-prone clearings. An 800-foot section of a waterside roadway was rebuilt with permeable pavers, transforming it into an effective treatment feature.

The benefits of the system were immediately apparent. Flood-prone homes and low-lying spots are no longer inundated after heavy rains. Runoff is now filtered naturally to remove pollutants before it enters the bay. The Maryland DNR estimates that the filtration features at Sylvan Shores remove an estimated 44.60 pounds of nitrogen and 4.97 pounds of phosphorus from stormwater runoff each year. A shining example of creative stormwater management, the project has prompted neighboring communities to consider similar systems for their own stormwater management needs.

Key Features

  • Grass swales and micro-bioretention structures provide natural filtration and require minimal upkeep to remain effective.
  • Rebuilt roadway filters runoff and creates a waterside promenade.
  • Native noninvasive plantings improve runoff treatment and add visual appeal.

Awards & Recognition

  • Honor Award, 2018, American Council of Engineering Companies (ACEC) Maryland, Engineering Excellence Awards.


  • Half-acre sand filter reduces phosphorus in runoff by an estimated 61 percent and nitrogen by 39 percent.
  • Roadway made with permeable pavers reduces phosphorus by an estimated 29 percent and nitrogen by 25 percent.
  • The system keeps an estimated 4,300 pounds of suspended solids out of the Chesapeake Bay each year.
  • Effective treatment of stormwater runoff before it enters the Chesapeake Bay.
  • Prevention of street, yard, and residential flooding following heavy rains.
  • Roadside filtration features and plantings add visual appeal to the community.
  • Support for state pollution reduction goals in the Chesapeake Bay watershed.


Sylvan Shores Services Company


Riva, Md.


Conceptual and Final Design, Permitting, Community Outreach

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