Cyanobacteria

New Hampshire’s Department of Fish & Game is facing a potential lawsuit over water pollution from its largest fish hatchery.

The Conservation Law Foundation told the state Thursday it plans to file a Clean Water Act lawsuit this fall, unless the state begins working to fix the alleged problems within 60 days.

The Powder Mill hatchery in New Durham grows trout and salmon to stock state fishing areas, and it’s expanded in the past decade or so.

A team of researchers is sampling lakes across the Northeast this week as part of efforts to better understand what’s causing cyanobacteria blooms.

The blooms have become common in other parts of the country, including the Midwest, and are starting to pop up locally in New Hampshire and surrounding states. Scientists are unsure what’s driving the change.

The New Hampshire Department of Environmental Services is warning those who visit a park in Hopkinton of a bloom of cyanobacteria that might produce health concerns.

The department released the advisory about a bloom at the Elm Brook Park Beach on Tuesday. It says people and pets should avoid contact with the water in places where the lake has surface scum or green streaks.

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.

Cyanobacteria advisories are in place at Elm Brook Park beach in Hopkinton and Silver Lake State Park Beach in Hollis. 

State officials are urging visitors to stay out of the water if they observe blue-green scum or clumps suspended in the water column. Cyanobacteria can be toxic to both humans and dogs.