The fact is, the Colorado River's flow is apportioned among all the
states in its watershed via the "Colorado River Compact", which
allows so many acre-feet to go to California, Nevada, Arizona, etc.
as well as the upstream states. The trouble is, the total "yield" of
the river was calculated based on the wettest decade in history: the
1920's. Since then the annual flow of the Colorado has only
approached that average in a few years; the result is that the river
is "in deficit" most years, and severely so recently with the low
Rocky Mountain snowpacks. Further complicating the issue is our
treaty obligation with Mexico to deliver at least 1 million acre-
feet to Mexico where the river crosses the border. (Furthermore, to
make such water usable, we had to build a multibillion-dollar
desalinization plant at Yuma, AZ.)
The only reason the whole house of cards hasn't collapsed is that
Nevada has always deferred collecting its share of the Colorado
(which I believe is 4 million acre-feet), allowing that water to go
toward filling Lakes Mead, then Powell, and later to go to
California. Now, Las Vegas has drawn down all its groundwater and
needs water to support its cancerlike growth. The trouble is, that
water will have to be either found somewhere else (taken from rural
Nevada in an Owens-Valley-like power grab), or wrestled loose from
California in court (enforcing the Colorado River compact).
Of course, this whole problem can be solved via CONSERVATION, but we
don't do such picayune things, here in the land of excess.
The fact is, we are now starting to pay for the hubris of settling
fifteen million people in a land that can only support 100,000 (LA
Basin). Las Vegas is similar, with 1.5 million people in a land that
can only support two cockroaches and a jackrabbit.