From NH DES...

You may use the tell-tale signs of cyanobacteria to initially identify its presence in the water, however, cyanobacteria may be positively identified to the Genus level only by microscopic identification. If you suspect a cyanobacteria bloom at your lake or pond, please call DES immediately at 271-2457 or email beaches@des.nh.gov and we will conduct a site visit. 

You may collect a sample in a clean plastic or glass container and deliver it to DES to identify. (29 Hazen Drive, Concord, NH 03302-0095,  M-F, 8am-4pm) 

Caution: If collecting a potentially toxic algal sample: Avoid contact with skin. Wear water-proof gloves when sampling and/or immediately wash all areas of the body where water contact has occurred.

Bow Lake, Northwood	Webster Lake, Franklin	Lake Monomonac, Rindge