While this looks similar to the end stage of an intense algae bloom, it’s really only plant pollen. One telling difference is the color: this stuff is decidedly yellow whereas dead cyanobacteria is bright green. I suspect it’s pollen from White Pine though I’m not sure. In any case, it’s a natural phenomena and there is no reason to believe pollen has an impact on water quality though for a short time it can impact lake water transparency. While it looks ugly, it is of a short duration and will eventually disperse into the water column and sink. Another difference between pollen and algal blooms is the timing: pollen events happen in the Spring whereas algae blooms are typically a mid-to-late Summer and early Fall phenomena. Here are a couple of pictures of cyanobacteria on my shoreline taken in October of 2013. The color is decidedly different:
The more you know!