The Massachusetts Department of Public Healthís list of ponds and lakes under a blue-green algae advisory has expanded -- from nine a week ago to 12 on Friday.
The list now includes a section of the Charles River, from Newton to the Moody Street Dam in Waltham, Cliff Pond in Brewster, and East Monponsett Pond in Halifax.
The state posts advisories if the cyanobacteria levels exceeds 70,000 cells per milliliter.
Some algae blooms can produce toxins and irritate the skin and eyes, trigger asthma-like symptoms and if swallowed in large amounts, harm the liver.
Blue-green algae has been a problem this summer throughout the Greater Boston area, closing popular swimming spots. Many communities have warned swimmers to stay away and residents to keep their pets out of the water.
Boating is still allowed along the affected section of the Charles River, but paddlers should avoid touching the water and wash off after any contact.
This algae thrives in nutrient-rich, warm water, according to state health officials, and this yearís weather has likely contributed to its spread.
A total of 12 water bodies are under advisory, up from 9 last week. In addition to the three new locations, they include Crystal Lake in Newton, Horn Pond in Woburn, Lovellís Pond in Barnstable, Mollís Pond in Eastham, Santuit Pond in Mashpee, Stevens Pond in North Andover, Walkerís Pond in Brewster, Wedge Pond in Winchester and West Monponsett Pond in Halifax.
Deirdre Fernandes can be reached at email@example.com