Is it just me, or is there a new "weed"?

[KTO]

All summer, I've noticed globs of green floating in the water, at all depths. Sometimes I'd see it at the top of the water, sometimes floating near the bottom. I almost mistaked it for a rock near the surface today! Sometimes when we're swimming, this stuff becomes a REAL mess! What is up with this stuff? Has it always been there? I thinks I've seen it before, but this years seems one hundred times worse!