EagleTribune.com, North Andover, MA

Merrimack Valley

March 11, 2013

Selectmen to review plan to protect Stevens Pond

NORTH ANDOVER — Public Works Director Bruce Thibodeau is expected to present a recommendation to the Board of Selectmen tonight on how to prevent Stevens Pond from being overrun by blue/green algae.

The selectmen are scheduled to begin their session at 7 a.m.

Last year the summer swimming season at the pond was ruined when large blooms of blue/green algae, which are actually cyanobacteria, showed up. The town was forced to close the pond for most of the summer.

Cyanobacteria cause humans to break out with a skin rash. As for dogs, who love to play in the pond, these microorganisms can be fatal to them if they drink the contaminated water.

Thibodeau declined to provide details of his recommendation when questioned by The Eagle-Tribune last week. He did not want to publicize it before presenting it to the selectmen, he said.

A few weeks ago, biologists with Aquatic Control Technology, a firm that advises the town on water quality, said the cyanobacteria can be driven away by several measures, including:

The application of chemicals, such as copper and aluminum sulfate, commonly known as alum; aeration; flushing the pond; use of ultrasonic frequencies, which disrupt the cell structure of cyanobacteria; placing barley straw into the water, the decomposition of which releases a substance that helps get rid of cyanobacteria.

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