It initially looks like pollen, except that it is not floating on top of the water but it is suspended in the water below the surface. We initially thought it was pollen but noticed this and the fact that there was not pollen anywhere else: not on the boat cover, not on the deck furniture, etc.
Our clear beautiful water in our cove on west Bear Island turned to pea soup literally overnight, and has been gradually improving since then.
These are some photos that were sent to NH DES on Monday.