THEY PLAN TO FILL HOLE by DROPPING ROCKS FROM HELICOPTERS "Crisis eases but more than 100,000 evacuated near Oroville Dam" - The Orange County Register

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He added that they have a plan to plug the hole.
"That would include using helicopters to drop bags of rocks into the crevice to prevent any further erosion," he said.
Authorities drastically increased the amount of water allowed out of the main spillway, from 55,..."
http://m.ocregister.com/articles/oroville-743865-spillway-water.html