Visually observing blue-green algae is the first step in closing a public swimming beach.
Since July 30, the county Health Department has closed four swimming beaches because of blue-green algae. Mark Stow, county environmental health director, said once the ''unmistakable'' visual of the algae is spotted in the water near a public beach, it will be shut down for swimming. Blue-green algae forms thick mats on the water surface resembling paint and can range in color from gray to various shades of yellow, green, blue or brown.
''When the bloom disappears, then we go sample the water,'' Stow said.
After getting the water sample, county officials send it to state officials who run tests to determine toxin levels. If the water is determined safe, the beach can be reopened. The process typically takes two days.
Stow said county officials have a couple ways to determine if a public beach has a blue-green algae bloom present. He said the county has Jim Metzger, who oversees the beach water quality program with help from SUNY Fredonia interns, and through assistance from beach operators.
''We build a rapport with them so they let us know what conditions are, as well,'' he said. ''Typically, we sample beaches a couple times a week during season, which is Memorial Day to Labor Day.''
With four beaches being closed within the past few weeks, Stow said it looks like the blue-green algae problem will continue. He said how long a bloom stays in the water cannot be determined.
''It certainly could be a day or two, or longer. It is hard to tell,'' he said. ''It depends on the existing conditions.''