The following is from the Town of Arlington:
High levels of cyanobacteria (blue green algae) were detected at Spy Pond during water sampling performed by the Massachusetts Department of Public Health. Water samples are being collected and monitored on a weekly basis. This Public Health Advisory will remain in effect until cell counts drop to safe levels for two consecutive weeks.
Historically, this advisory has been in place through late September. Please checkarlingtonma.gov/health for updates.
Some types of cyanobacteria can be toxic if ingested in high doses and can cause skin irritation and a rash after wading or swimming. The Arlington Board of Health strongly advises residents not to swim or stand in the water and especially urges residents to keep pets away from the water.
Cyanobacteria are bacteria that grow naturally beneath or on the surface of many water bodies. Under certain conditions (such as warm weather and an abundance of nutrients in the water) the algae may undergo an explosive type of growth that results in dense, floating mats of algae. This is commonly referred to as an “algae bloom.”
Contact with high levels of the cyanobacteria algae has been found to contribute to eye, ear, and skin irritation. During an algae bloom, the amount of algae and toxin in the water can become elevated and exposure can be potentially harmful to people and animals.
Health concerns vary depending on the concentrations of cyanobacteria and its toxins. Ingestion of elevated concentrations of the algae and its toxin can lead to more serious health effects (e.g. muscle cramps, twitching, and liver damage).