1983 was not that unusual. It wasn’t unusual for the US Dept. of Reclamation to fail to hit the target for how full to let Lake Mead get. What was unusual was that it was so obvious.
You see, if your target is to fill Lake Mead to the 65% level, and you make a mistake and it ends up filled to 80%, no one but your supervisor will be able to tell. The casual observer can’t see the difference.
But when Lake Mead is already 90% full and your target is 95% but it actually goes to 101% – well, that’s what happened in 1983. The video shows water coming over the spillways at the top of the dam. Bureau of Reclamation actually placed six-foot tall plywood extensions to make the spillway even higher, to stop the spectacle.
I was reminded of all this as I checked on the snowpack above Lake Powell. We’re only a third of the way through the water year and still holding above average, and much better than recent years past. We are reminded of the folly in trying to forecast each year based on last years’ activity, even for the “experts”.