A few years ago, a levee on the Yuba River broke during flood stage and a town and farmland were flooded, for a month or so. Who knows how many million dollars worth of damage was done. Why do we have to depend on the Army Corps of Engineers, taking bids for contracts on the repair work? It seems like this is a state and local matter, and can be handled locally more efficiently, as was actually done by the county sheriff and a trucking company, skipping the paperwork, stepping in and doing the job. But dumping rocks in the levee break seems like a slow, crude, brute force method of repair, rather than first aid.
I think basically the same technique could have been used to for first aid on both the dam and the levee break. Admittedly being an armchair engineer, I think of materials like the pre-utility poles I sometimes see in storage yards, and plastic sheeting. In the case of levee breaks, to slow further erosion, first line it with plastic, staked and weighted in place at the upstream end. If the break is not too big, poles or logs are floated up to the break, spanning it, pushed to the bottom, and more pushed down on top, to form a wall of horizontal poles, then covered with plastic, then rocks and dirt. The poles are of course held firmly in place by the water pressure. If the gap is too wide to be spanned by poles, first a cable is stretched and firmly anchored across the break. Then poles are lifted at one end by helicopter, and dropped just upstream of the cable. Hopefully they drive into the bottom, and are supported on the downstream side by the cable to form a loose picket fence across the break. Then more poles are laid lengthwise, smaller poles added if needed, and sealed with plastic etc. Then you can think about permanent repairs with rock. Similar techniques could have been used for emergency repair to the dam, and much easier. If the lake side of the dam was smooth, poles could easily be put in place either horizontally or vertically. It's maybe a little off the subject, but I started thinking in this direction as a result of a science fiction story. The research scientists unexpectedly created a matter-transmitting passage a few feet off the ground, about six feet across, to somewhere in space, a "worm hole" in Star Trek lingo. Since the great majority of the universe is a very good vacuum, it quickly sucked up the laboratory, the scientists, and was working on removing the earth's atmosphere. (Isn't there an energy problem here, in matter moving from the bottom of a gravity well to outer space?) Other scientists couldn't find a way to destroy the hole. The engineer hero, after demanding a deed to the property as payment, used a big tank-like vehicle with arms to clap two hemispheres of heavy steel around it, thereby stopping the escaping air. My first method (actually that I evolved while writing this) would have been to put a big steel pipe, open at both ends, on a flatbed trailer, use cables to move it in around the hole, then slide steel plates over the ends, both ends simultaneously, then cover pipe, trailer and all with concrete. But it might be simpler to just start with a big boulder instead of the pipe. Actually