Flat Creek’s “Gravely Grand Canyon” is one of the fastest eroding tributaries in the South River watershed, with over 11,000 linear feet of highly incised and unstable channels.
Stream banks are 6.9 feet high on average and as high as 18 feet in some areas. The project will begin on community property owned by the Gravely Community Association and end on the County-owned Kings Branch Flat Creek Greenway Natural Area. Restoration is planned for 3,270 linear feet of stream channel. The project area drains 208 acres, of which 17 are impervious. The project, when constructed, will prevent 2,060 pounds of nitrogen, 697 pounds of phosphorus, and 40.5 tons of sediment from entering the South River each year as well as create and enhance habitat.
Sediment, or dirt, is the number one pollutant for the South River both by volume and by impact to wildlife. High concentrations of sediment and nutrients coming off the land cause the water to be cloudy and prevent sunlight from reaching the bottom of the shallows. Without sunlight, the grasses cannot grow, and if the grasses do not grow, then there is not enough oxygen or habitat. Additionally, sediment serves as a vehicle for nitrogen and phosphorus, carrying it into the river. Over the years, stormwater has carved a deep gully through the woods. The sediment that used to be in that gully, is now in Flat Creek and the South River.
With the Watershed Assistance Grant, the Federation has hired a professional design firm to design a restoration project to abate the erosion and reconnect the floodplain where possible. Following construction, the site will be planted with thousands of native plants. This will prevent further erosion entering Flat Creek after each rainfall, and allow water to re-enter the system through groundwater. In addition to the water quality benefits, this project will create and enhance wetland habitat for native flora and fauna.
The Federation has secured design funding and is currently working on obtaining construction funding. The pictures below show large gullies, carved from the surrounding stormwater runoff.