Cyanobacteria is extremely harmful to dogs if ingested, and can even kill them.
South Portland Parks and Recreation has posted signs warning beachgoers of a toxic blue-green algae bloom in Hinckley Park. Credit: CBS 13

Dog-killing algae has been found in South Portland ponds for the fifth year in a row.

The algae bloom was found in the ponds of Hinckley Park, according to a spokesperson for the city of South Portland.

The algae, called cyanobacteria, is extremely harmful to dogs if ingested, and can even kill them. It can also cause rashes and stomach illness in humans. The city urges people to keep their pets away from the ponds and to wash their hands and anything else that has come in contact with the pond water.

The city has posted warning signs at the entrances to the park and around the ponds. It’s working on curbing the algae by planting native plants along the lower pond’s shoreline and monitoring water quality. The city urges community members to curb the cyanobacteria by picking up after pets, staying on trails and avoiding areas with eroding soil.

It will die on its own once temperatures cool — the bacteria’s optimal growth temperatures are above 68 degrees Fahrenheit, according to  a 2015 research report by the Southern California Coastal Water Research Project.

Jules Walkup is a Report for America corps member. Additional support for this reporting is provided by BDN readers.

Jules Walkup reports on the midcoast and is a Report for America corps member. They graduated from the University of Georgia with a degree in journalism and moved to Maine from Tampa, Florida in July 2023.