Putting it bluntly, California's economy would collapse without...

Putting it bluntly, California's economy would collapse without adequate water to sustain it's agriculture.  If it were to collapse, it would do a huge amount of damage to the US economy as a whole.

In other words, they simply can not afford to dick around.

"In 2013, California's agricultural exports amounted to $21.24 billion in value, representing a 15 percent increase over the previous year. In terms of value, California's top three agricultural exports are almonds, dairy and dairy products, and wine. California's share of total US Agricultural exports for 2013 was 14.7 percent or slightly more than the 13.1 percent share reported the previous year."

http://www.cdfa.ca.gov/statistics/