Cyanobacteria reported on Winnisquam, warning issued in Barnstead

Though a citizen reported a potential cyanobacteria bloom on Lake Winnisquam this week, there are no cyanobacteria warnings or watches in place there, or on Lake Winnipesaukee, headed into the weekend. 

A citizen observed a bloom on Lake Winnisquam in the area of Pond Road in Belmont, near the shoreline while boating on July 28, according to New Hampshire Department of Environmental Service’s Healthy Swimming Mapper.

The observer described the appearance of the bloom as mixed, with both surface scum and material through the deeper water. A sample collected the next day indicated 720,000 cells per mililiter of planktothrix, exceeding the benchmark of 70,000 cells per mL. 

A cyanobacteria warning is issued on a waterbody when samples exceed 70,000 cells per mL at multiple locations. A watch may be issued based only on a photograph, when the cyanobacteria density is approaching 70,000 cells per mL, when only one sample exceeds 70,000 cells per mL, or when the bloom material has passed. 

It’s worth noting that cyanobacteria reports provide information from a specific point in time and may not reflect current conditions on a given body of water. NHDES advises the public to avoid making contact with the water in areas where bloom material is observed as well as restricting pet access to the water.

On Lake Winnipesaukee in the area of Sobel Road near Black Island and Moultonborough Neck, a bloom reported on July 22 is still listed on the map. A member of the public observed that bloom while standing along the shoreline, and described it as heavier at deeper points in the water column, resembling a snow globe in appearance.

A sample collected on July 22 indicated a stigonema cell density too numerous to count. 

On Huntress Pond in Barnstead, DES staff issued a cyanobacteria warning on July 29, after sampling conducted on July 28 indicated a planktothrix and dolichospermum cell density too numerous to count. 

That bloom is described as having the appearance of green flecks and clumps of material.

According to DES staff, the average duration of a cyanobacteria warning is 23 days. Last year, August and September saw the most cyanobacteria warnings issued, with 21 and 14, respectively.

Warnings do not close a body of water to recreation, but DES staff advise activities near visible bloom material should be avoided. Cyanobacteria material grows lake-wide, and accumulates on the shoreline due to wind, wave and boat action. The whole waterbody may not be simultaneously affected, but material can move around to various parts of the lake.

When a warning is issued, resampling is performed weekly until a bloom subsides, according to DES staff. Warnings are issued between May 15 and Oct. 15.

“Cyanobacteria blooms are capable of producing cyanotoxins that can be harmful to domestic animals, livestock, wildlife, and humans,” information provided by DES reads, in part. “The type and amount of cyanotoxin produced varies over time and from lake to lake. Cyanotoxins can cause both acute and chronic illnesses that can target the skin, liver, kidney, and central nervous system.”

You can report a suspected bloom using an NHDES tool online at survey123.arcgis.com/share/151c9fc3c8214c2e93325f77e0f1d578.

The report form provides visual examples of various cyanobacteria blooms. You can provide the date you observed the bloom, the specific location of the bloom, the name of the waterbody, your own vantage point when observing the bloom, characteristics of the bloom, photographs and other specific details. 

And there were no beach advisories due to fecal bacteria in the Lakes Region as of Thursday afternoon, though there was one in effect at Hampton Beach. Beaches in Laconia remained free of bacteria advisories, Assistant Director of Facilities Matt Mansur said Thursday afternoon. 

They'll test Laconia's beaches again in August, after the area has a few sunny days behind it — rain tends to skew the results, he said.

Stay up to date on water conditions all weekend at des.nh.gov/water/healthy-swimming/healthy-swimming-mapper.