The New Hampshire Department of Environmental Services says it is seeing an increase of dangerous levels of cyanobacteria in some lakes and ponds.
The most recent advisories include French and Keyser ponds in Henniker, Sebbins Pond in Bedford and Lee's Pond in Moultonborough. Warnings have been posted at sites affected by the bacteria and also at public beaches with advisories for fecal contamination, such as Opechee Park Cove Beach in Laconia. Conditions include surface scums, or streaks, or blue-green flecks in the water.
The DES says short-term health effects of being exposed include skin irritation. Long-term effects can cause kidney, liver, or central nervous system function.
Department spokesman Jim Martin says it's important to know the warnings don't include the entire body of water, just the affected area.