Best line about water management I ever wrote:

Wet years have a way of covering up a multitude of water management sins. Drought exposes them for all to see.

Water supply. Migratory camp for cotton pickers. San Joaquin Valley, California. American River camp. by Dorothea Lange, Farm Security Administration, 1936

It also helps to expose those sins, apparently, if you have satellites. Here’s Jay Famiglietti, talking about what the GRACE satellites show about groundwater depletion in California’s Central Valley:

During the drought of 2006-2010, state and federal surface water allocations were drastically reduced, forcing farmers to tap groundwater reserves far more heavily than in ‘normal,’ wetter years. The resulting volume of depleted groundwater was so great that it was registered by a satellite ‘scale’ that orbits about 400 km above Earth’s surface.

It gets worse:

[T]he combined Sacramento and San Joaquin River basins have already lost 10 cubic kilometers of fresh water each year in 2012 and 2013.

That’s nearly a Lake Mead a year. Clearly, in a variable climate, farmers in the Central Valley have planted far more acreage than the system’s water supply can support on  some time scales we can now clearly see. They will plant less. That’s inevitable.

It’s Stein’s law, in action: “If something cannot go on forever, it will stop.” But Stein’s law, glib as it is, masks an important set of policy questions. In its basic form, it’s an argument for the lack of need to do anything. Water conservation will come to California when the surface supply is short and the groundwater has run out and some significant portion of the farms are permanently fallowed. The water management sin being exposed here is the failure to pursue a more graceful exit strategy for the communities that will suffer as a result.