Rhode Island officials have declared 10 places off-limits for swimming.
The Providence Journal reports the closed swimming areas include the upper and lower ponds of the Kent County YMCA, Oakland Beach, the Saunderstown Yacht Club and the pond at Camp Cookie.
Routine state testing found high levels of unsafe bacteria in those waters.
Officials also added the Slack Reservoir in Greenville on their list of four ponds made toxic by blue-green algae.
The state Department of Health warns not to eat anything caught in the ponds. Pet and human skin that makes contact with the water should be rinsed, as well as clothing.
