That topic comes up every once in a while on Pond Boss.

Here is a link to a decent thread. (I don't know if there are some better ones?)

Blue-green Algae

It seems to form mostly in very nutrient-rich ponds. Or ponds that have been recently fertilized, or ponds that have had fertilizer wash in after a big rain event such as cow manure or ag fertilizer.

Any of those happen to you? (I guess your cut grass into the pond would slightly increase the nutrients?)

I don't believe there are any quick fixes.