By RUSTY DENNEN
The second swimming advisory of the season has been posted at Fairview Beach, and it will be tomorrow afternoon before follow-up water tests determine whether people can go in the water over the holiday weekend.
Bacteria levels spiked in the Potomac River along the popular King George County shore in Monday's weekly water sample. Test results came back yesterday and the signs went up warning against swimming.
Under state health guidelines, levels of 104 or more enterococcus bacteria on lab culture dishes trigger a swimming advisory.
Monday's tests at the four Fairview Beach sampling sites showed a level of 1,260 when the four sample sites were averaged. That's more than 12 times the allowable limit.
Higher-than-allowed bacterial readings are common at Fairview Beach following heavy rain.
Bacteria are a concern because excessive amounts can cause gastrointestinal problems, especially in the young, the elderly and those with compromised immune systems. No water-borne illnesses have been reported due to the contamination.
Michele Monti, program director of the Division of Zoonotic and Environmental Epidemiology for the Virginia Department of Health in Richmond, said yesterday that the recent rains probably caused the spike.
There was so much rain, she said, that follow-up tests were pushed back a day.
"Normally we would go out the next day. But because of the amount of water coming down the Potomac, we decided to wait a day," she said. "I'm fairly certain that the bacterial level is still high."
Some wastewater treatment plants in the Washington, D.C. area were flooded and released raw sewage into the river because of the flooding, but it's unknown whether any of that might appear in upcoming water samples downriver.
A day of sunshine, which will cut the amount of runoff from the shore, combined with the bacteria-killing effect of the sun's ultraviolet radiation, Monti said, might bring levels down dramatically.
"My thoughts are that, if we give it a day, especially if there's no more rain, a sample would be in compliance and we could lift the swimming advisory."
The sample will be taken around 2 this afternoon and sent to the state laboratory. Results take about 24 hours, so no determination can be made until tomorrow afternoon.
The King George Health Department had been doing the water testing, but the state is doing it this swimming season, which runs from Memorial Day through Labor Day weekend.
Enterococcus bacteria are not harmful in themselves, but indicate the presence of microbes potentially harmful to anyone who comes in contact with the water.
The first advisory at Fairview Beach was posted June 12. The water was tested again, and still came back with higher-than-allowed numbers. The advisory was lifted June 20.
The state Health Department monitors 48 public beaches, most of them on the Chesapeake Bay or Atlantic Ocean. So far this year, two swimming advisories have been posted at Virginia Beach and Fairview Beach.
Advisories have been common at Fairview Beach over the past two years and health officials have been working to determine the source of the contamination.
Studies last year found that they came from a combination of human, pet and wildlife waste. But how and where the bacteria are entering the water is unknown.
Scientists determined that the contamination was probably tied to runoff because bacterial levels are higher when sampling follows heavy rain.
Monti said finding the source at Fairview Beach is more difficult because there are multiple types of waste involved.
Monti said the state will take a closer look at Fairview Beach this season.
"I would like to get an answer on what is causing this," she said. "But with nonpoint source pollution, it can be very difficult."
To reach RUSTY DENNEN:
Email: rdennen@freelancestar.com