Cohasset is carrying out an eight-step plan to restore the treasured Meetinghouse Pond in the Cohasset Common to its former beauty.
The pond was plagued with thick algae for several weeks, drawing numerous complaints from residents and causing unexpected headaches for the town before being scooped out late last month.
Recent testing conducted by the Cohasset-based center for Student Coastal Research showed the pond had a highly alkaline pH level, which promotes algae growth, and a very low dissolved-oxygen level, at 28.9 percent.
“For the ideal fish pond, one would hope to get as close to 100 percent dissolved oxygen as possible,” said Felix Zemel, Cohasset Board of Health agent.
According to town officials and scientists, many things could have caused the high pH and low dissolved-oxygen levels, including the new concrete siding, the broken recirculation pump, and a lack of organic growth at the bottom of the pond.
The eight-step plan was drawn up at a July 25 meeting of Zemel, Acting Town Manager Michael Milanoski, and the student research center. The town officially adopted the plan at the July 31 selectmen’s meeting, where three high school students from the center, along with their college mentor, gave a PowerPoint presentation outlining the steps to prevent a future algae infestation.
The plan entails draining the pond, cleaning the water pump and the pond, adding sand at the bottom, refilling the pond with tap water from the Water Department, dechlorinating the tap water, turning the pumps and fountain back on to aerate and boost the dissolved-oxygen level, adding starter bacteria, and monitoring the pH and dissolved-oxygen levels.
The three students, Erin Driscoll, Christine Guinee, and Alexandra Lanier, along with Ashley Howard, a college intern at the center, will measure the pH and dissolved oxygen twice a week until the levels are stabilized.
The first step on the list has been checked off: The pond has been drained. The water commissioner, Peter DeCaprio, said the Water Department and the town are trying to reach an agreement on a “fair and equitable price” to refill the pond. Milanoski said in a telephone interview that he expects the pond to be refilled by the end of next week.
Selectmen chairman Paul Carlson called the students’ proposal “very thoughtful and well done” and said the town is committed to creating and maintaining a healthy pond.
Ann Thomae, a chemist and leader at the research center, said the students will report the test results to Zemel.
If the pH becomes imbalanced again despite the fresh water and aeration, Thomae said, they would use chemicals to balance it. “We hope to get to the point where fish will be able to live in [the pond].”