I read the info on the lake. I had no idea the west end was so shallow. Reminds of my swimming pool (at my old house). The first day it got really hot, the following day the pool was green. Had to shock the doo doo out of it and it was a salt water pool.
Yup the shallowness of that end would be a problem.
As someone else pointed out this algae seems to thrive on Phosphorus so fertilizer run off may have contributed.