COLUMBUS -- Just days before Buckeye Lake's annual July Fourth boat parade, state officials are warning visitors not to swim or wade in the water off Brooks Beach.
There already was a toxic algae warning there, but increased amounts forced officials to elevate the warning.
At the same time, less-severe algae bloom advisories -- not to swallow water or touch surface scum -- were removed from the lake's Crystal and Fairfield beaches.
"This doesn't change anything for the boat parade," said Don Carley, chairman of the holiday event.
He said the parade will take place Monday near Lieb's Island about half a mile away from Brooks Beach.
Blue-green algae are fed by phosphorus runoff from manure, fertilizers, and sewage.
Toxic algae were first detected in Grand Lake St. Marys in western Ohio in summer 2009. Last year's bloom emerged in late June, covering sections of the lake in scum.
In all, 20 public waterways in the state were affected last year.
As of June 24, the amount of toxic algae at Brooks Beach had dropped enough for any warnings to be removed. Then last Monday, the algae returned and at higher levels.
"It's kind of the nature of the beast," said Erin Strouse, spokesman for the Ohio Environmental Protection Agency. "[The algae] can come and go, and it's hard to predict."
Ms. Strouse said higher temperatures can help "cook" the algae and bring blooms to the surface.