Posted on July 24, 2024
The Fairfax County Board of Supervisors has signed off on a four-year, $1.14 million partnership with the United States Geological Survey (USGS) to examine sediment levels in Lake Accotink and Accotink Creek and identify the best strategies for preserving the lake.
The partnership follows a December 2023 recommendation by a task force of community members, environmental groups, nonprofits, and a Park Authority representative that found preserving 20 to 40 acres of the popular Springfield lake could be a viable alternative to either fully dredging it or letting it fill up and disappear.
While the task force provided models and estimates of sediment entering and leaving Lake Accotink, Braddock District Supervisor James Walkinshaw emphasized at the board’s July 16 meeting that these were only estimates and that more concrete data was needed before moving forward.
“So this partnership with USGS will install gauges so we will actually know how much sediment is entering the lake and how much sediment is leaving the lake,” he said.
According to a county staff report, the partnership will allow the county to gather data to guide future management strategies for the lake, which has faced significant sediment buildup due to urbanization.
Constructed by the U.S. Army in the early 1900s as a reservoir for Fort Belvoir (formerly Fort Humphreys), the 55-acre Lake Accotink has been a significant environmental, recreational, and community resource for over 100 years. However, since the 1950s, rapid urbanization has led to sediment erosion and travel within Accotink Creek, causing sediment buildup in the lake, per the task force’s report.
In 2023, county officials recommended against dredging the lake due to high costs and environmental concerns. Instead, they proposed exploring other options to maintain the lake, including calculating how much sediment has built up over the years.
In January, the board directed county staff to conduct a cost analysis and timeline for the sedimentation rate study and a feasibility study for preserving a smaller lake.
County staff noted in their report that USGS was chosen for the sedimentation rate study due to their extensive experience and nearly two-decade-long partnership with Fairfax County in monitoring local water quality and sediment levels.
The study, running from fiscal years 2025 to 2028, will focus on Lake Accotink and its feeder stream. The lake study will measure sediment buildup and downstream movement, while the stream study will identify sediment sources in Accotink Creek and analyze sediment movement and deposition.
“I think this is exciting for the entire county,” Walkinshaw said. “It’s exciting for those of us who are passionate about saving Lake Accotink, but it’s also going to help us learn some things that are going to be more broadly.”
The project will be funded by Fairfax County, with USGS contributing $50,000 towards equipment. The study’s results will be released to the public once it is finished.
The Fairfax County Department of Public Works and Envirionmental Services is also scheduled to give an overall update on its plan for Lake Accotink at the Board of Supervisors’ environmental committee meeting tomorrow (Tuesday).
