An automated continuous water monitor the state installed at Budds Landing detected a sudden spike in a pigment, indicating that blue-green algae were clouding the water. State workers collected a water sample Thursday and identified it as Microcystis, said DNR biologist Catherine Wazniak.

Microcystis, which grows only in fresh water, releases a pair of toxins into the water that if ingested in sufficient quantity can damage the liver and nervous system of animals or even humans. While it doesn't appear bad enough yet to warn people to stay away from the water, that has happened in the past. The Sassafras has had severe blooms before.

The threat isn't theoretical. Nearly three years ago, two dogs died within hours of swimming in a Microcystis-infested lake in Dorchester County. And Camp Todd, a Girl Scout camp near Denton in Caroline County, lost the use of its Lake Williston the past two years because Microcystis blooms were poisoning the water and turning it pea-green. No illnesses were traced to the lake, but its closure affected the camp.

"It was kind of sad," recalls Bob Foote, the camp's manager. The campers would learn how to canoe and kayak by practicing paddle strokes on the lake's shore, he said, then have to load their gear in a truck and drive to another lake.

Last summer, in a bid to rid the lake of harmful algae, Foote said he drained it and let it sit empty through the winter before refilling it this spring. He also tried a remedy local farmers swear by, spreading 550 bales of barley straw across it.

Place, who's been studying the lake, says it's not clear how barley straw works, but it does seem to at least prevent the blue-green algae from growing. Lake Williston is free of toxic algae now, Foote says, and ready for use when camp opens later this month. But Place says he continues to monitor the water, and wouldn't be surprised if it returns.

Indeed, harmful algae blooms have a way of recurring in the same places every few years, when weather conditions are just right. For some blooms, a major factor is water temperature, and as the earth's changing climate warms coastal waters, O'Neil and other scientists say they expect more frequent outbreaks. The bay's average water temperature has risen 2.5 degrees Fahrenheit since the 1960s, they note.

"The fact is we're going to see more of these events, more blooms and more fish kills," says Kevin Sellner, executive director of the Chesapeake Research Consortium, who has spent much of his career studying algae blooms.

With algae blooms a threat to fish, pets, people and tourism, scientists and others are casting about for ways of predicting where and when they'll strike — and for ways to treat them to reduce their impact. State and federal researchers have been working on a computer forecasting system, says DNR's Wazniak, but so far have only been able to spot blooms forming a few days ahead of time.

Treatment is even more iffy. Place said he's investigating ways to knock down Microcystis blooms, using everything from draining an infested lake to dosing it with various chemicals.

An earlier version misidentified the location of the Corsica River. The Sun regrets the error.

tim.wheeler@baltsun.com

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