There a bunch of RETARDS!!!!
It may appear to be idiotic to pay for nothing but it is standard practice to pay a contractor to stand down from a project. Many times, especially for a project of this magnitude, a contractor has spent enormous sums to prepare for a project. In this particular case, the contractor has spent tens of millions of dollars on drag lines, off road dumps, other earth moving equipment and support equipment before the first blade cut the ground. There is a real and very large expense just to have the equipment sit. In addition, you need to be able to keep manpower available for when the notice to proceed is issued.
The question that comes to mind for me is what the Corps plans to do with the nearly 3/4 of a BILLION cubic yards of spoil dredged to create the reservoir. It seems to me that they certainly could corner the market for aggregate with that much rock coming out of the ground. Yes, there is several feet of muck on top but it's solid limestone below that (why do you think the water just sits there? it can't percolate through the rock). It might be interesting to see if that's the real reason the Lakes Region quarries were shut down. They claim the presence of benzene, but the levels were barely detectable and were traced to the type of blasting caps that were being used. Once those types of caps were eliminated, so was the benzene but the efforts to close the quarries persisted. If you want to make some money selling something, how convenient that you have the power to close down your competitors.