It looks like they cleared up most of the algae at the Olympics sailing site by shifting a million tonnes of algae. I am not exactly sure how much a tonne is but I believe that a million of them is a staggering crap-load. They used close to 50 km of fishnet barriers, 1,400 boats and 10,000 troops and volunteers. There are still 3 weeks to go but it looks like they have it under control.
You can see video here, c/o of the BBC. They still have a bit of a fog problem.
Pretty impressive!