A major bloom of blue-green algae has been discovered in part of the Charles River, prompting a public health advisory for people not to swim, fish, boat, or take part in other forms of recreation. The algae, formally known as cyanobacteria, was confirmed downstream of the Longfellow Bridge on Thursday by the state Department of Public Health.

The Massachusetts Department of Public Health has listed part of the Charles River in a harmful cyanobacterial bloom advisory.

BOSTON - The Massachusetts Department of Public Health has confirmed a cyanobacteria bloom at Longfellow Bridge’s downstream of the Charles River. This the first major bloom in four years and is being considered a public health advisory.