Smaller Lake Accotink Preservation Feasibility Study

Lake Accotink provides valuable recreational opportunities to Fairfax County residents and supports a variety of wildlife. Lake Accotink is important to people from different cultures and backgrounds, for many reasons. However, due to the large, developed area upstream, and the significant amounts of sediment that flows into the lake, continuing to dredge the lake to maintain its current size might be too expensive, too impactful to our natural resources, or too disruptive to adjacent communities.

The Smaller Lake Accotink Preservation Feasibility Study is an effort to better understand what is happening within Accotink Creek and Lake Accotink and identify what actions may be feasible to maintain a smaller lake in a sustainable, equitable, and cost-effective manner. In late 2023, the Task Force on the Future of Lake Accotink found that a smaller lake, 20 to 40 acres, may be the best option to preserve an open water feature. The work of the Task Force also documented the need for additional study and analysis.  In response to the report from the Task Force on the Future of Lake Accotink, the Fairfax County Board of Supervisors has initiated the following studies:

• Sedimentation Rate Study - to better understand how much sediment is transported to Lake Accotink from Accotink Creek, and how much is escaping (or exiting) the lake downstream.

• Dam Assessment – to determine the improvements and maintenance needed to ensure long-term regulatory compliance and safe functioning of the Lake Accotink Dam.

• Feasibility Study – to assess the feasibility of preserving various smaller lake options, 20 to 40 acre 4 to 8 feet deep and determine the best management methods, planning level costs, regulatory and permitting challenges, maintenance dredging intervals, and other key aspects. 

Background

Lake Accotink was constructed by the United States Army in 1940 as a freshwater supply for Camp Humphreys (now Fort Belvoir). Intense development in the 30 square mile watershed draining to the lake following World War II resulted in the lake losing 50 percent of its capacity. This was due to continued development in the watershed, mostly prior to the issuance of stormwater management regulations, which increased overland runoff eventually causing streambank erosion and contributed a significant amount of sediment to the lake. The US Army dredged the lake prior to transferring it to Fairfax County in 1967. The County dredged the lake two additional times, in 1985 and 2008.