Accotink Creek Gets a New TMDL

from DEQ presentation

Last Friday, Will Isenberg of the Virginia Department of Environmental Quality (DEQ), Office of Watershed Programs ad Ecology presented an update on the development of the sediment and chloride Total Maximum Daily Load (TMDL) for Accotink Creek, a 51-square-mile watershed located in the center of Fairfax County that drains southeast to Accotink Bay, then Gunston Cove and finally to the Tidal portion of the Potomac River. Accotink Creek watershed includes Bear Branch, Crook Branch, Daniels Run, Hunters Branch and Long Branch tributaries and Lake Accotink, approximately 70 acres in the central portion of the watershed.

My husband spent summers in the early 1960’s playing on Lake Accotink, so it is featured in family lore and hearts. Though we no longer spend time at Lake Accotink or the nearby park, we pay attention to the health of that watershed and have watched from a distance as the health of the watershed declined. Accotink is an impaired watershed. For the last 20 years the DEQ has developed plans, with public input, to restore impaired streams, lakes, and estuaries. These plans are called "Total Maximum Daily Loads," or TMDLs. Following the U.S. EPA's approval of a TMDL, an Implementation Plan is developed to restore the watershed. This is all done under Section 303(d) of the Clean Water Act.

The first attempt at a TMDL for Accotink Creek was to use stormwater runoff as a surrogate for sediment loading in the stream. However, Fairfax County and the Virginia Department of Transportation (VDOT), sued EPA on the basis that stormwater runoff is not, itself, a pollutant . In January 2010 a federal court ruled that the U.S. Environmental Protection Agency (EPA) exceeded its authority in establishing a flow-based total maximum daily load (TMDL) for Accotink Creek. The court decided the case in favor of the plaintiffs, Fairfax County and the VDOT. The ruling was based on the view that while EPA can dictate the pollutants attributed to a TMDL, Congress is the body who defines what a pollutant is.

Now the DEQ has developed a new TMDL this time controlling Sediment and Chlorine to restore the health of Accotink Creek. A public comment period will end on 21 July 2017, after which the final report will be prepared, unofficially forwarded to the EPA for their concurrence, and forwarded to the Virginia State Water Control Board for final approval before official submission to the EPA.

The EPA lists sediment as the most common pollutant in rivers, streams, lakes and reservoirs. Sediment is the loose sand, clay, silt and other soil particles that settle at the bottom rivers and lakes. Sediment entering stormwater degrades the quality of water for drinking, wildlife and the land surrounding streams. This sediment can come from soil erosion or from the decomposition of plants and animals. Wind, water and ice help carry these particles to rivers, lakes and stream. According to the EPA natural erosion produces 30% of the sediment in our streams and lakes, erosion from human use of land accounts for the remaining 70% - the most significant sediment releases come from construction activities, including relatively minor home-building projects such as room additions and swimming pools, landscape projects.

Chloride while present all year round is increasing average annual concentration. The chloride in Accotink Creek spikes in the winter. Severe winter weather requires an effective and affordable means of de-icing roadways- road salt. Though calcium chloride is also used it is much more expensive sodium chloride (road salt), which is composed of 40% sodium ions (Na+) and 60% chloride ions (Cl-). The sodium, chloride and impurities make their way into our environment through the runoff from rain, melting snow and ice, as well as through splash and spray by vehicles and by wind. They find their way onto vegetation and into the soil, groundwater, storm drains, and surface waters causing significant impact to the environment. Virginia’s freeze and thaw winters produce several spikes of chloride.



Chloride is toxic to aquatic life and impacts vegetation and wildlife. There is no natural process by which chlorides are broken down, metabolized, taken up, or removed from the environment. EPA's threshold of 230 mg/L is the concentration of chloride above which the water is unsafe for wildlife. Chloride runoff from highways has been measured over 20,000 mg/L. However, we can’t just eliminate road salt- it is a public safety issue and Fairfax County and VDOT will have to figure out how to balance environmental needs with public safety. The newest methods of salt application using brine sprayed on roads which are better for the environment and more cost effective, but very corrosive to automobiles.