This is a terrific article which lays it all out.
http://www.wsj.com/articles/californias-green-drought-1428271308
No major water infrastructure has been completed in California since the 1960s due to environmental obsessions.
Construction of water retention infrastructure and desalination plants are confronted by years of insane environmental lawfare.
Environmental rules forbid pumping excess water from the north Californian catchment to reservoirs in the south.
And the Democrats insist on pouring fresh water into the sea.
I watched a show on the science channel, I believe, where this guy was getting permits, then tearing down damn, so the salmon can come back there after a century of the fish being gone.
That is partially true
But you need to be more specific.
The enviros have very specific tools that they use to block dams:
Endangered Species Act(Nixon)
Clean Water Act(Nixon)
California Environmental Quality Act(Gov Reagan)
Also, financing is a problem.
Prop 13 makes it harder to raise money
The federal govt reduced spending on dam building. For many, many decades beginning early in the 20th century the feds heavily subsidized not just the dams but also the irrigation projects that distributed impounded water to the growers. Prez Reagan played a big role in reducing the federal money.
The third and biggest reason is that California already has 1400 dams so most all of the good locations to build a dam already has a dam. So the cost benefit ratio is higher on new dams. More money per gallon impounded.