The work is proceeding apace at the Oroville Dam, where the winter of 2017 tested a 50-year-old piece of water infrastructure, and it failed the test. As we learned in April, the very expensive, very urgent job of replacing the dam's spillway has to be completed or at least a usable version needs to be completed by the time the rain starts up again in November.
Major erosion to the dam's main spillway led to the first ever use of the dam's emergency spillway essentially just a 30-foot-high concrete lip that lets water pour down a hillside. As officials began to see that the ground beneath the emergency could give way, a massive evacuation of some 200,000 people downstream took place one Sunday in mid-February. After that, the heavily damaged main spillway was put back into use several times in order to lower the water level in Lake Oroville, and now crews contracted by the state Department of Water Resources have just five months to get a new concrete spillway built that can handle water releases of 100,000 cubic feet per second.
The plan is to then resume construction in the summer of 2018 to complete a more robust, permanent spillway with a capacity of 270,000 cubic feet per second.
Drone footage from this week puts into perspective just what an enormous job this is.