Scale. Building all of the 17 planned desalination plants would decrease the water deficit by 0.54 million acre-feet (MAF), but the actual shortfall is around 10 times that. It'll also take years to bring those online.<p>You can try out solutions like that here, in the 'California Water Challenge' game:
<a href="http://www.cawaterchallenge.org/responses" rel="nofollow">http://www.cawaterchallenge.org/responses</a>
Desalinization is expensive.<p>A lot of the places undergoing severe drought aren't near the coast. Transporting water uphill is even more expensive, both in energy costs to pump and in construction, right-of-way, and repair costs.<p>The new cost model is not compatible with some of the current economic systems. Cattle ranching requires a lot of water. It's not obvious that the cost of building a replacement system is justified.<p>You might as well as "why are ppl complaining? Why don't they just move?"<p>Both are expensive, though the latter also has emotional and civic costs that are harder to measure than desal water.