The Delaware Center for the Inland Bays (CIB) has partnered with the Delaware Health and Social Service’s Stockley Center on a project to reduce stormwater runoff to Cow Bridge Branch, a stream that runs through Doe Bridge Nature Preserve.
Located near Georgetown, the 315-acre Doe Bridge Nature Preserve is one of the most biologically-unique areas in Delaware. Because of the ecological significance, the campus of the Stockley Center is a priority restoration area for the CIB.
Similar to other developed areas, the impervious cover (hard surfaces) of the Stockley campus generate runoff during storm events. When stormwater runoff moves over land, it picks up and carries pollutants from lawns, streets, and industrial facilities into nearby waterways.
Because Cow Bridge Branch stream drains into Indian River through Millsboro Pond, pollutants that enter the water upstream will eventually enter Indian River and the Inland Bays.
In July 2016, the CIB was awarded a Community Water Quality Improvement Grant to convert a failed stormwater pond at Stockely to a bioretention facility: an area planted with native plants and engineered to capture and filter rainwater. Unlike a traditional stormwater pond which holds the water—providing minimal water quality benefits – this retention area allows water to slowly soak into the ground where the plants, soil and mulch capture and filter pollution.
“The original stormwater pond, built in 2000, was ineffective and allowed sediment and nutrient-laden runoff to enter the Cow Bridge Branch directly – without treatment,” explains Chris Bason, Executive Director of CIB. “Untreated stormwater runoff is a major source of pollution to the Inland Bays.”
Construction was completed in December 2016, and the bioretention area will be planted in May 2017. Once complete, the project will result in a keep 2 pounds of phosphorus, 17 pounds of nitrogen, and 514 pounds of sediment from entering the stream each year.
This is the second restoration project that the CIB and the Stockley Center have partnered on in recent years. The first project completed in 2014, restored the headwater channel of Cow Bridge from a closely mowed grassy area to a natural channel lined by a buffer of native trees, grasses, shrubs, and wild flowers. This restoration slows the flow of water and filters the runoff before it enters Cow Bridge. CIB hopes to continue to restore the natural habitats and quality of water along this stream in the future.