Columbus Dispatch...
Grand Lake St. Marys had algae in March, tests show
Warnings won’t be posted till late May   
May 10, 2012 

Tests show toxic blue-green algae were growing in Grand Lake St. Marys as early as March this year. 

The most-recent test, on April 18, detected the liver toxin produced by the algae at a concentration seven times higher than what the state uses to advise older visitors, young children and people with weakened immune systems not to wade or swim. 

State officials said warning signs won’t go up at the 13,000-acre western Ohio lake and state park until Memorial Day weekend, the start of the state’s swimming season. 

“At this point, there may be some boating on Grand Lake,” said Carlo LoParo, spokesman for the Ohio Department of Natural Resources. “However, there is no water-skiing or full-body contact with the water because of lake temperatures.” 

Blue-green algae, also called cyanobacteria, are common in most Ohio lakes. They grow thick by feeding on phosphorus from manure, fertilizers and sewage that rain washes from farm fields into nearby streams. 

As many as 19 public lakes, including Erie, have been tainted in recent years by toxic algae. 

Algae grew so thick in Grand Lake in 2010 that the state warned people not to touch the water. Officials say it likely caused seven people to get sick that year. The algae can produce as many as four toxins. 

The concentration of toxins was reduced in 2011 after state officials treated the central 5,000 acres of the lake with alum, a chemical that starves algae by bonding with phosphorus. 

The state also has established a multiyear effort intended to limit the manure spread on farm fields south of Grand Lake. Manure-contaminated runoff from those fields is considered a prime source of the algae-feeding phosphorus in the lake water. 

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