Thursday, May 24th, 2012
Lake algae toxins decline
Levels remain high enough to warrant warning signs
By Amy Kronenberger
GRAND LAKE - Algae toxin levels in Grand Lake have dropped from last week, but warning signs will still go up today.
Water samples taken Tuesday and released this morning show toxin (microcystin) levels range from 38.6 parts per billion at Windy Point Beach to 10.7 ppb at the Celina Water Treatment intake pipe.
The state's recommended threshold is 6 parts per billion. The World Health Organization's guideline for recreational contact is 20 ppb, which is considered the upper end of the moderate risk range.
Water samples taken last week, when a brown scum was floating on the lake in some areas, showed toxin levels ranged from 24 to 72 ppb.
Grand Lake St. Marys State Park Manager Brian Miller said he was encouraged by this week's lower test results.
Ohio Department of Natural Resources spokeswoman Bethany McCorkle stressed the tests, which are done every week, are only a snapshot of that moment; the numbers are always changing.
If all samples test below 6 ppb for two weeks in a row, the state will remove the warning signs, McCorkle said.
Warning signs will be placed at the four beaches where algae educational signs already are up. The educational signs, which show what algae looks like and tell people how to report it, were placed at Grand Lake and several other lakes across the state that have had algae problems.
The new signs will read "Warning - High levels of algal toxins have been detected. Swimming and wading are not recommended for the very young, the very old and those with compromised immune systems."
"Everyone else, enjoy the water but be on the lookout," McCorkle said this morning. "If you see an area that looks like spilled paint, avoid it."
McCorkle this morning said the main type of blue-green algae in the lake remains to be planktothrix. Samples taken April 25 showed planktothrix made up 92 percent of the algae in the water. Planktothrix, which typically gives the lake its familiar blue-green color, has been the lake's dominant algae for years.
Officials still don't know why the suspected algae appears brown this year, McCorkle said this morning. She also said state officials are not focusing on finding a reason for the color change.
In 2010, the blue-green algae aphanizomenon took over and coated the lake in thick, blue, white and green mats that emitted a horrible smell as the algae decayed.
Officials say an alum application in April is not responsible for the tea-brown color that became visual more than a week ago. Alum deactivates phosphorous, which is the toxic blue-green algae's main food source.
The other results of the samples taken Tuesday were 11.9 ppb at Campers Beach, 11.6 ppb at West Beach and 10.9 ppb at East Beach.
For more information on the test results, go to www.ohioalgaeinfo.com