From Jay Lund, a comment on my post last week about low flows into that is worth elevating:

Perhaps a bigger issue is that average unimpaired flow appears to be < 11 maf, but total allocations are more than 16 maf/year (1.5 maf/yr for Mexico and 7.5 maf each for the upper-basin and lower-basin states). Mexico and the lower basin states already use their full allocations. As upper basin state use grows, water storage in the amazingly large Colorado R. reservoirs will diminish over time. We will blame droughts and climate change, but overallocation is a more than equal contributor to the problem. Improving allocations will have large economic benefits.