State Department of Public Health workers canvassed homes surrounding Santuit Pond yesterday afternoon, issuing severe restrictions to avoid even boating on the pond, due to the presence of a potentially toxic type of algae.
The warnings, to avoid nearly any type of summer recreation on the pond, were issued in response to the discovery of levels of blue-green algae above state health guidelines, according to a spokesman for the state public health agency.
Boating and jetskiing are not recommended because they may spray water containing the algae in the air, leading to inhalation or other contact, according to the warning. Skin contact with the algae can causes rashes; ingestion of it can cause more serious illness, according to information from the state.
“As I read it, the state is basically recommending that you stay out of it and stay off it,” said longtime Santuit summer resident Frank Harker, who reported receiving the notice yesterday afternoon.
A weekly water quality test conducted by the state on July 29 found 73,000 cells of blue-green algae per milliliter of water, above the recommended safety threshhold of 70,000, according to information provided by Mashpee Health Agent Glen E. Harrington.
Blue-green algae can be harmless or highly toxic, depending on conditions in the pond. It can turn toxic quickly and without obvious warning signs, according to Mashpee Shellfish Constable Richard H. York.
Mr. Harrington said the town has not received any confirmed reports of humans or animals becoming sick from the pond. A rumor has been spreading about a dog getting sick, but he said that should be dismissed because it was not documented or proven. “Does the stuff have the ability to do that? Yes, it does. But the animals have to drink a ton of water in order to,” Mr. Harrington said.
On July 20, the state found low levels of blue-green toxin in the pond, the first time the toxin was documented this summer. No immediate warning was issued, however, because the toxin was found at less than one part per billion parts of water, and the state has set a recreational contact health guideline at 14 parts per billion.
The stern warning comes as the town is preparing to address the long-running problem of phosphorous pollution, which feeds the overgrowth of algae in the 172-acre, shallow pond.
The Mashpee Community Preservation Committee recently voted to send to October Town Meeting a $357,000 proposal to install water circulator devices in the pond.
The town is drafting a request for proposals to determine what specific technologies and vendors can provide the service, though the citizens group Friends of Santuit Pond has identified SolarBee as a strong contender. SolarBee has proposed installing six solar-powered water circulators in select areas around the pond, machines that are intended to deliver oxygenated water from the surface down to the bottom, preventing the release of phosphorous from muck built up on the bottom of the pond.
The circulators would not be a permanent fix to the phosphorous problem but, as long as they are running and functioning property, would prevent the worst symptoms of the overabundance of nutrients.
After The Crash
The warning also comes at an interesting time for the pond this summer, a period when visibility of the pond is markedly improved over recent years.
According to observations by residents and Mr. York, the pond showed its usual bright green algae bloom—a phenomenon that lends the pond an electric pea soup appearance—in June and and early July.
However, around the second week of July, the bloom disappeared, the result of a natural occurrence known as a “crash,” according to Mr. York and Eduard Eichner, a senior water scientist from the University of Massachusetts Dartmouth School for Marine Science and Technology.
According to Mr. York, visibility in the pond was at least six feet in mid-July, way up from the typical visibility of a foot or less in recent summers.
The state testing of blue-green algae followed a similar course, building up through the early summer, plummeting in mid-July, and recently reaching back up to potentially dangerous levels.
Even now, nearly a month later, the neon green shade of years past has not returned.
“At this point there are no blooms,” Mr. Harker said. “The pond is uniformly what I would call a dirty green color. There is very little smell. It is not like past years.”
Mr. Eichner said such a sequence of events represents a common phenomenon in freshwater ponds. “The population can get so big and all of the nutrients are sort of tied up in that plant community, so there is no way it can sustain that level of growth. And that is when you get a crash,” he said. “Can you get to that full bloom condition again? Sure. You just need to get back to where the phosphorous is high enough to support it.”
Mr. York said he is unsure of the cause of the crash but is investigating several theories, including that a type of microscopic animal he noticed during water quality monitoring may have consumed the algae.
Bacteria A Separate Issue
At the town landing off Timberlane Drive, two seemingly contradictory signs are posted, one with a warning to stay out and another stating that the pond is safe for swimming.
According to Mr. Harrington, the signs provide information on two separate tests performed by two separate agencies.
In addition to the state public health department, the Barnstable County Department of Health and Environment conducts regular testing on six freshwater and three saltwater beaches in Mashpee, as well as dozens of others in other towns on the Cape. Health officials test the water, and if organisms that indicate the presence of bacteria are found above a regulated level, the beach is closed. Health officials then test on subsequent days until the water has cleared, and the beach can be reopened.
The most recent bacterial tests at Santuit Pond have come back clear.
Beaches at the pond have been closed, however, on four separate occasions this summer. Starting July 7, Bryants Neck failed four consecutive tests before being reopened on the July 13. The town landing has also been closed for two days.
According to health officials, the bacterial problems are thought to be caused by animal feces, road runoff, and perhaps failed septic systems, a separate issue from the nutrient issue causing the algae blooms.
On Thursday afternoon, as state public health officials were warning residents about the condition of the pond, state Division of Marine Fisheries workers were in boats on the pond, reportedly conducting a fish survey.