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Toxin-producing Microcystis aeruginosa floats on the water at Aquia Bay Marina.
Skiers, swimmers and boaters are being warned to avoid contact with toxic algae that have built up in Aquia Creek.
Stafford Parks and Recreation worker Travis Ray posts no-swimming signs along the beach at Aquia Landing. |
BY JIM HALL
and RUSTY DENNENThe Virginia Department of Health is advising people and their pets to avoid contact with the water in portions of Stafford County's Aquia Creek.
Health officials issued the advisory Thursday night because of the presence of Microcystis aeruginosa, a type of blue-green algae that produces a harmful toxin.
Because of the warning, Stafford officials banned swimming yesterday at the county's Aquia Landing park.
"We don't want them to enter the water until we get word that it's clear," said Cathy Riddle, public information administrator. "We don't know how long that's going to be."
The park is located at the mouth of Aquia Creek where it meets the Potomac River. The park will remain open, Riddle said, though signs have been posted urging visitors not to enter the water.
Officials also have placed brochures in marinas on the creek, warning boaters and water skiers about the algae.
"It's going to be a hot weekend, and a lot of people are going to be out boating, and we want to make sure they're safe," Riddle said.
George Paxson, manager of Aquia Bay Marina, first noticed the algae about a week and a half ago.
"It looks like a very green hue to the water," he said yesterday. "There are tiny, green flecks in the water. If you have more hot days, it will get greener and greener."
He added, "It is visible, but not as heavy as it's been in the past."
Boaters, he said, "should be careful if they go in the water, and try not to ingest any of it. The ones I'm concerned with are young people tubing or on Jet Skis--anyone who would have contact with the water."
He says recent strings of extra-hot days, such as the ones the area has had over the past two weeks, trigger algae growth.
"We don't have it all summer, just when you have extremely high temperatures," Paxson said.
Gary Switzer, environmental health manager for the Health Department, said yesterday the algae is common in the fresh waters of Virginia.
"In this case, the concentration is higher than what's normal."
People who come in contact with the algae or the water surrounding it may experience skin or respiratory problems. If the affected water is swallowed, the toxin can produce abdominal pain, jaundice, malaise or vomiting.
"The particular concern is with pets," Switzer said. "The toxins seem to really affect them. They get it on them, and it can be fatal."
Switzer said the advisory applies only to those areas of the creek with concentrations of the algae.
He said he advised leaders at Coles Trip Camp, a Girl Scout camp on Aquia Creek, to steer campers away from those portions of the creek.
"You have to be right adjacent to it or in it to cause problems," he said.
Thomas Faha (pronounced "Fay"), director of the Virginia Department of Environmental Quality's Northern Regional Office, said agency staffers doing regular water-quality monitoring on the creek noticed the bloom Monday.
Lab samples confirmed high cell counts of blue-green algae.
"This is fairly typical: a wet spring and a lot of runoff, followed by very dry weather or hot spell. And it's not just on Aquia, we see it in other [creeks] as well," he said.
Numerous species of algae are naturally present in the water; it takes certain conditions for them to grow exponentially.
As to where and why it happens, Faha said, "I liken it to a thunderstorm: Some areas get it, and some don't."
The algae appear to be concentrated in the vicinity of the railroad bridge over the creek.
Faha says the bloom could persist for a couple of weeks, or until there's a thunderstorm or some heavy rain. As the algae begin to die and decompose, robbing the water of oxygen, a fish kill also is possible.
Massive blooms of blue-green algae have happened occasionally along the Potomac, in 1970, 1981 and 1983, for example. The blooms have been linked to hot weather and nutrients such as nitrogen and phosphorus.
Ed Merrifield, the Potomac riverkeeper, says the toxic algae, and the warnings to stay out of the water, should not be ignored.
"This has killed cows," he said of the type of algae found in Aquia Creek. Most algae do not harm people or wildlife.
Algae blooms, he says, are a symptom of larger pollution problems in the Chesapeake Bay and its feeder tributaries.
The Maryland Department of Natural Resources earlier this month reported a giant "dead zone" growing in the bay. Dead zones--areas that can't support marine life--affect the estuary every summer, but this one is more widespread.
Nitrogen and phosphorus nutrients from fertilizer and from animal and human waste are the fuel.
A bloom of a brownish-red Karlodinium algae affected a 30-mile stretch of the Potomac, upstream of Colonial Beach to Sandy Point, in 2007. That caused fish kills, including a large one on July 11 of that year.
"It's not that we're just having a bad year and everything's OK. It's not," Merrifield said.
Jim Hall: 540/374-5433
Email: jhall@freelancestar.com
Blue-green algae are single-celled organisms that use sunlight to make food. When there are enough nutrients in the water, they can grow rapidly, or "bloom."
People can be affected by the toxic type in three ways: swallowing water, direct skin contact or breathing airborne toxins from the algae.
