Queen Sewell Pond will remain closed for at least another week due to an algal bloom—this, according to the Massachusetts Department of Public Health.
Bourne health agent Cynthia A. Coffin said that results from a water sample taken by the state on Tuesday showed lower levels of algal cyanobacteria; however, the state’s recommendation was to keep the pond closed until another testing is completed next week.
“Precautionary closure of Queen Sewell will remain in effect at least until results from next Tuesday’s testing, which we should get next Thursday,” Ms. Coffin said.
The state public health department reported that the water sample taken on Tuesday showed cyanobacteria levels of 30,000 cells per milliliter, below the MDPH guideline of no more than 70,000 cells per milliliter.
State department of health guidelines require samples collected a week apart to show levels below the 70,000-cell threshold before the advisory can be lifted. This week’s sample will be considered the first low result, and the water will be tested again next Tuesday.
Ms. Coffin closed Queen Sewell Pond on Monday, July 28, because of an algal bloom that was detected the previous week during regular water testing. The Massachusetts Department of Health was then asked to come to Bourne to test the water.
That first sample, taken last week and tested by the state, had 109,000 cells per milliliter. By mid-week, it was reported the number of cells had tripled to 350,000. Ms. Coffin explained at the time that the cells release a toxin when they die and the state was concerned about the increased level of toxicity in the water, once all of those cells die off.
The pond was closed to swimming, and residents were advised that they and their pets should not drink the water.
Ms. Coffin said that algal blooms often can result from a combination of heavy rains, stormwater runoff possibly containing fertilizer, and high temperatures. She said that several years ago, there had been some stormwater remediation done by Bourne conservation agent Brendan C. Mullaney in conjunction with the Bourne Department of Public Works. Those efforts seemed to alleviate the problem from 2010 to 2012, but she confirmed that she has had to close the pond each of the past two summers.
Queen Sewell Pond was closed for a little more than a week last summer and several days in 2009 due to algal blooms. Ms. Coffin said that the state DPH guideline of sampling the water twice before lifting a closure could be a new policy, adopted by the agency this year.
She said there has been no issue with algal blooms at any other ponds in town.