"There was a large bloom in mid-lake on Monday," Foster said. "It smelled like decaying grass and onion."
Blooms were not found in the vicinity of a much larger swimming area at Bee Run Beach, adjacent to Hunt's marina, but corps officials said blooms were found at sites upstream and downstream from there.
Toxins might or might not be present within the blooms, and blooms can be moved by wind and waves, leaving toxins behind in clear water.
By Tuesday, however, water samples taken at the lake showed that concentrations of Anabaena had dropped below 20,000 cells per milliliter, well below the corps' safety threshold. By Friday, no blooms were visible on the lake.
South Abutment Beach was reopened to swimmers Friday afternoon. Warning signs across the lake were replaced with advisory posters, cautioning lake users not to drink lake water, to avoid swallowing water while swimming and water skiing, and to avoid areas with visible algae accumulations.
If the concentration stays below 20,000 cells per milliliter for two weeks, advisory posters regarding the algae blooms will be removed.
"That should be on July 9," Foster said.
Foster said it is not known what triggered the blue-green algae blooms at Sutton Lake, the first West Virginia reservoir to produce noteworthy concentrations of the substance. What caused concentrations of the algae to dissipate back to safe levels also remains a mystery.
"It's a relatively new phenomenon in this region, showing up in Ohio in the past five or six years," Foster said. Nutrient loads, temperature and exposure to sunlight are all believed to affect the growth of the algae.
There are too many variables at play to know what makes the algae strain come and go, he said.
Hunt said the Corps of Engineers was right to inform the public of a potential health hazard, but he thought the agency could have taken more care in how news of the algae bloom was presented to the public.
"The corps put out a news release that was accurate, when it announced that the swimming beach at South Abutment was being closed," he said. "What they didn't say was that beach represented less than one tenth of a percent of the lake's shoreline. That night, TV stations reported that the lake was closed, and two minutes after the warning posters went up, they were on Facebook, and the rumors began to start."
Hunt said he hopes boaters and other lake users will receive enough correct information on the lake's status to enjoy spending the Fourth of July weekend at the cool, clear reservoir.
"We're open and we're looking forward to people coming here for what is usually one of our biggest weekends," he said. "Up until last Friday, this has been a super season for us."
Blue-green algae cell counts will be posted on the Huntington District's website, here.
Reach Rick Steelhammer at rsteelham...@wvgazette.com or 304-348-5169.