Santuit Pond has gone from a scummy green to relatively clear in the course of a few months after solar-powered water circulators were installed. Still, the state has found an unacceptably high level of potentially toxic blue-green algae two weeks in a row.
“I have been a biologist for about 40 years and I don’t think I’ve seen this before,” said Mashpee Shellfish Constable Richard H. York Jr. “The visibility is much greater. Visually we are seeing it, but we are not seeing it in the data. That is unusual.”
The SolarBee circulators, which were installed in April, seem to have changed the dynamic of the pond, Mr. York said.
Oxygen is reaching the bottom and you can see aquatic plants. The water is much clearer, with visibility up to 37 inches at the landing, compared to just 12 inches last year. Fishermen told Mr. York yesterday that the large-mouth bass they are catching are healthier and larger than in years past, similar to fish they catch on Mashpee-Wakeby Pond.
“This visibility has huge implications for fish,” Mr. York said. “The whole system gets changed.”
Why the blue-green algae count is measuring so high is a puzzle, Mr. York said.
Last Thursday, the state Department of Public Health measured 88,000 blue-green algae cells per milliliter, exceeding the state guideline level of 70,000 cells per milliliter. On Tuesday, the pond spiked to 127,000 cells per milliliter, again triggering the state warning that will continue for at least two more weeks.
Blue-green algae can be toxic to humans and animals, but the state found that toxicity levels were not a concern.
Mashpee Health Agent Glen E. Harrington posted warnings last Friday at three locations at Santuit Pond: the town landing, the Santuit Pond Association beach, and Bryant’s Neck. The signs alert swimmers that the algae can turn toxic at any time.
Members of the group Friends of Santuit Pond said they remain cautiously optimistic about the performance of the SolarBees. The Friends were a major force in lobbying for the devices, which were purchased by the town with Mashpee Community Preservation Committee funds. One member of the Friends group, John M. Kabat, noted that the blue-green algae count is about the same as in years past and that it will take more than one year for the machines to be effective.
Another member, Allen Waxman, suggested that the measurement of blue-green algae may not be representative of the entire pond, a theory that Mr. York supported.
“The way the wind blows, it could be thicker at the town landing,” Mr. York said.
Mr. York pointed out that the current blue-green algae count is still less than half of the highest sample recorded, 278,000 cells per milliliter, taken on August 25, 2009.
Still, Mr. York said he was surprised by the high count this week. Using the state’s method for sampling, Mr. York tried to replicate the results yesterday and could not.
“We have to assume that the [state] data is correct,” he said.