Levels of dangerous bacteria found earlier this month in a Charlottesville stream have returned to normal, according to Charlottesville officials and tests conducted by the Rivanna Conservation Alliance.
Water quality monitoring conducted by the Alliance in March detected elevated E. coli levels in Pollocks Branch in the vicinity of Elliott Avenue and Rockland Avenue. City officials issued a warning for residents to avoid the waterway.
E. coli bacterium is a type of fecal coliform bacteria that can cause disease, severe illness and even death. When it is found in water, it is a strong indicator of sewage or animal waste contamination.
City crews investigated the surrounding area in an attempt to identify the source of the problem but could not find where the E.coli was entering the stream.
Pollocks Branch is a true inner-city waterway that spends most of its flow beneath the city streets. It runs through the town beneath pavement, re-directed in a pipe beneath the Downtown Mall and continuing out of sight as it flows beneath the IX Art Park before returning to its natural banks near Elliott Avenue.
The stream then runs toward Jordan Park and into Moores Creek.
The Rivanna Conservation Alliance conducted two rounds of follow-up monitoring after the discovery. The first round of tests showed declining levels of E. coli. The second round showed that levels had returned to normal.
Officials said that, given the steady decrease in E. coli levels and the lack of evidence of a source, the elevated levels were likely related to rainfall and associated runoff.
The Alliance will continue to conduct monthly bacteria monitoring on Pollocks Branch.
The city saw a second stream impacted by pollution earlier this month when someone reported a fish kill in an unnamed tributary of Meadow Creek.
State water quality investigators and Charlottesville firefighters counted 842 dead fish, 130 dead salamanders and 40 dead worms in the tributary. The E.coli and the fish kill were not related, officials said.
“City and Virginia Department of Environmental Quality investigations were unable to determine the source of the material that caused the fish kill,” city Water Resources Specialist Dan Frisbee said at the time. “DEQ biologists that conducted the stream impact assessment hypothesize that it was caused by a toxic liquid, potentially a surfactant (soap or detergent), but its origins are unknown.”
The area affected by the fish kill extended from Barracks Road to Emmett Street. Meadow Creek was not affected by the pollutant, likely because it was diluted by the larger stream.
Because urban streams may carry a variety of contaminants, Frisbee advises that resident avoid the streams during or soon after it rains. That’s when pollution levels are likely to be higher due to runoff from city streets and the area’s stormwater drains.
He also recommends people do not get into the streams and waterways if they have any open cuts or sores and recommends washing hands or using sanitizer after contact with the streams, especially before eating.
City officials also recommend wearing shoes in the water and not swallowing stream water or getting it in ears, nose or mouth.