That sounds like symptoms of spiny water fleas.
https://en.wikipedia.org/wiki/Bythotrephes_longimanusUpdate: went to hay bay this past week and realized how alge was really in there. The water was very calm and shoreline top water was laced with green. Saw small clusters floating all througout the bay during the day. Avoided touching the stuff while launching thanks to reading this post. 2 girls swimming at the launch with toddlers at Shermans on the way back in, they left before we got in or I would have warned them although there are clearly posted warning signs at the launch.