Water is becoming so precious in the drought-stricken U.S. West that -- why not -- states are even taking steps to figure out how much of it they have.

California governor Jerry Brown in January challenged towns and state agencies to cut their water use by 20 percent. Now they're trying to measure what 20 percent means. It's hard. Cities and the state in some cases are coming up with estimates that differ by up to 10 times.

“Despite our longstanding water problems, we don’t accurately report and measure water in any sector -- urban or agricultural,” Peter Gleick, president of the Pacific Institute, a water think tank in Oakland, told James Nash of Bloomberg News. “That makes it difficult to implement programs to conserve water and deal with this crisis.”

In the Southwest, the Colorado River Basin remains “the most over-allocated river system in the world,” according to a study that will be published in Geophysical Research Letters.

The basin lost 64.8 cubic kilometers (15.5 cubic miles) of freshwater -- two-thirds of that disappearing from underground reservoirs -- over the time period in the study. That’s an amount of water almost twice the size of Lake Mead, the biggest U.S. reservoir, gone from the basin.

David Fuller's view

The US Drought Monitor map in the article above is alarming for California, resulting in more fires and damaging crops.  Dry weather in the South West region is also a potential concern for US crops where bumper yields were expected until recently.

Soybeans and wheat have steadied from oversold positions and corn could follow this lead, if dry conditions spread to the north.