Solving a Bacteria Mystery
Hampton Roads Sanitation District and Virginia Tech investigating the source of the enterococci contamination
The city of Hampton, Va., has been tracking the source of enterococci, or bacteria, that caused the closure of area beaches. Although no closures have occurred in early 2004, the city closed Buckroe Beach in August 2003 for 19 days due to high bacteria levels. The city enlisted the Hampton Roads Sanitation District (HRSD) and Virginia Tech to investigate the source of the enterococci contamination. Enterococci exist in fecal matter and pose risk to human health.
Bacteria detectives have been performing sampling and analyses to solve the mystery of the bacteria source, whether it is human, pet or wildlife waste. HRSD collected samples and monitored the water quality at Buckroe Beach, in conjunction with the Hampton Health District beach monitoring program. The Hampton Department of Public Works partnered with HRSD for sampling and analytical services provided through HRSD’s Municipal Assistance Program.
The agreement specified that HRSD collect samples and perform analysis for enterococcus, as well as measure pH, temperature, salinity and dissolved oxygen. The monitoring was conducted at two stormwater outfalls and two beach locations. Samples were collected from May to October in conjunction with the beach monitoring program. Additional samples were collected monthly during wet weather. The colonies of enterococcus were isolated and sent to Virginia Tech for monthly comparison analysis.
HRSD teamed with Virginia Tech, who is performing bacterial source tracking (BST), a method developed to determine the source of bacteria from environmental samples. Virginia Tech can identify the genus and species of enterococci to differentiate between human, wildlife and even pet sources as well as specific animal sources.
University scientists use DNA fingerprinting of enterococcus in the lab to target the specific sources. Virginia Tech collected fresh fecal samples from the field in order to analyze and characterize the DNA of the bacteria found in the samples. The DNA fingerprint of a field sample was entered into the database of catalogued DNA in the Virginia Tech DNA library. If all goes well, a match is made between the field sample and the source of the waste.
If the Buckroe Beach DNA match indicated human waste, the cause of causes could be failing septic systems, leaking sewer lines, cross-connected pipes, sewer line overflows or possible wastewater dumped from recreational boats. If dog waste were the culprit, then the city would need to enhance its stormwater education to urge dog owners to pick up after their pets. If wildlife is the problem, the city may need to consider relocating stormwater catch basins away from the beach.
The city of Hampton will use the analytical results from HRSD and Virginia Tech to help determine the course of action to pursue.
(Editor’s Note: Shortly before presstime, WWD was notified by HRSD officials that test results from Virginia Tech strongly indicated the source of contamination as birds and wildlife.)