White Pond in Concord is closed to beachgoers and swimmers until further notice due to a bloom of blue green algae, Concord Police said in a statement.
The algae bloom is dangerous for humans and toxic for dogs, police said.
The pond will remain closed until the water is deemed safe.
Concord Recreation and the Board of Health are closely monitoring the bloom, police said.
Caroline Enos can be reached at caroline.enos@globe.com. Follow her on Twitter @CarolineEnos.