Health officials are advising Arlington residents not to swim or stand in Spy Pond because of high levels of toxic algae found in the water.
The state Department of Public Health detected high levels of microcystis algae, which can be toxic if ingested in high doses and cause skin irritation and a rash after wading or swimming.
Arlington’s Board of Health is advising residents not to swim, stand or allow their pets in the water.
The public health advisory will remain in effect until the amount of algae drops to safe levels for two consecutive weeks.
Warm weather and an abundant of nutrients in the water can lead to explosive growth that result in dense, floating mats of algae, according to the town’s health department.
Microcystis is different from most types of algae because it contains and can secrete a toxin into the water. If too much is ingested, the toxin can lead to serious health problems including muscle cramps, twitching and liver damage.