Different New Hampshire towns seem to have a different procedure with cyanobacteria and closing their town swim pond or lake. Believe the state's procedure is to post their DES yellow w/black print 12"w x 18"h vertical style warning signs on a 48" wood stake, similar to a snow plow stake, along the water's edge and then leave it up to the individual town whether to close the water, or leave it up to the individual upon seeing the warning sign.
Yesterday, Saturday June 29, I asked how much to rent a sup paddleboard at the 7-acre Corcoran's Pond in Waterville Valley and was informed "$20 for one hour, except the pond is closed due to bacteria so we cannot rent out a paddle board." Renting a kayak or canoe was happening, but no sups, and no swimming. And, then I noticed three different DES yellow warning signs posted along the water on both sides of the pond.
https://www4.des.state.nh.us./WaterShed_BeachMaps/ as of June 30 ..... is for fecal bacteria ..... this link should be a blue link that works except it doesn't so try googling 'fecal bacteria Waterville Valley.' Probably is just some old poop from the ducks and the dam has maybe been closed lately due to dam construction and the major repairs ........ no worries!
At the Weirs Beach beach/swim area, the orange or yellow signs typically get posted into the beach sand, sometime in July after it flunks a NH DES water sample test , and many summer beach visitors go swimming, regardless, and the city doesn't close the water.
Different posts ...... different towns?
So, different towns have a different plan when the DES orange or yellow bacteria warning signs get posted into their local beach, swim area.