Dredging Efforts Set to Continue in Braddock District Lakes
Braddock District is blessed to have five lakes that provide habitat for
wildlife, enjoyment for residents and a method of protecting homes, roads
and businesses from catastrophic storm events. These lakes also hold
sediment, nitrates and phosphorous that would otherwise degrade our
streams, rivers and the Chesapeake Bay.
Fairfax County has a goal of establishing a dredging schedule in which each lake is dredged often enough that it has a 50 year capacity. The next lake to be dredged is Lake Barton, following the rehabilitation of the dam structure. The goal is to remove 36,000 cubic yards of sediment from this lake at a cost of $1.9 million. Lake Barton currently has a 75,000 cubic yard pool capacity and without dredging, would become a marsh by 2048.
When Lake Accotink was dredged in 2007-2008, over 200,000 cubic yards of sediment were removed at a cost of over $9 million. Lake Accotink lost 20 surface acres during the previous 15 years.
All of the lakes suffer from constant sediment incursions. While many believe that sedimentation is only a result of failure to control runoff from construction sites, the sedimentation that is shrinking Lake Accotink and silting up our other lakes is also due to the large amount of impervious surfaces in the Pohick and Accotink Watersheds. Instead of flowing across open land and being absorbed by the ground, water ends up rushing over parking lots, driveways, roads and roofs. The water speeds up so much that by the time it reaches the streams and creeks, it is moving quite rapidly.
It scours the banks of our streams and creeks and the newly released sediment is then deposited in the lakes; silting up most at the point where those streams enter the lakes.
Of the remaining publicly owned lakes in Braddock District, Woodglen Lake currently has a sediment pool capacity of 160,000 cubic yards, and at this time is holding an estimated 25,000 cubic yards of sediment. Royal Lake has the largest pool capacity at 416,000 cubic yards, but currently has 97,000 cubic yards of sediment. The stormwater planning staff proposes that the lake to be dredged after Lake Barton will be Huntsman Lake in Springfield. Finding nearby locations to haul dredged material has proven difficult but the County is looking at ways to turn this soil into a revenue product such as use as topsoil. At this time, approximately $500,000 per year is set aside to undertake dredging efforts that concentrate on clearing the forebays where sediment first enters our lakes.