State environmental scientists are in the midst of a lengthy probe into the poor condition of aquatic insects in two major Fairfax County watersheds, a problem that could have broader implications to the health of local streams.
The Difficult Run and Accotink Creek watersheds have both been listed as “impaired” because of the compromised health of their aquatic life since the mid-1990s, said Bryant Thomas, water monitoring planning and assessment supervisor for the Virginia Department of Environmental Quality’s Northern Virginia region.
It is unclear, however, what could be harming the insect populations. Thomas said the DEQ plans to finish a report identifying what could be causing the problem in spring of 2008, combining years of studies and ongoing water sampling. The results could have larger implications than just bugs.
“When we look at the bugs, what that tells us is more of an integrated longer-term perspective of the overall stream health,” Thomas said. “If there is a good population of bugs, there is the habitat, the water quality that provides for a healthy environment.”
The problem is not, however, unique to these two watersheds, Thomas said, and other urban streams have been impacted similarly. Urban areas, by their very nature, have a mass of “impervious surfaces” like sidewalks and parking lots, which speed rainwater and any pollutants that come with it directly into a stream.
The studies come amid a handful of other scientific probes into what is emerging as an unflattering environmental picture of Northern Virginia’s waterways. The DEQ, in coordination with Virginia’s game department, is investigating a rash of fish kills that have devastated bass and sunfish populations on the Shenandoah River in recent years.
