How the hell they gonna patch it with the water flowing so powerfully!? Dropping. Cement in? Rocks, half that shit is gonna be washed away!! That won't work... I've worked on water feature repairs, which lol I know doesn't compare to this, but I've used small amounts of hydraulic cement, which dries under water... The stuff works great when you don't have an insane amount of water flowing over it before it dries!! Idk if there is some special technique they use??