What's the cause of California's drought?

This week Governor Brown announced a drought relief package of $680 million for California farmers, farm workers, and others who have been or will be hurt by the current historic drought.  Just last week, the Washington Times published an oped by me and former Interior Department official Julie MacDonald, in which we explain that much of the pain of this drought is man-made.  To be sure, the paltry precipitation is responsible in part.  But, as we demonstrate in the oped, incredibly short-sighted and wrongheaded water allocation decisions motivated by whimsical environmental sentiment should receive the lion’s share of the blame.