Since the Golden State’s founding in 1850, California’s farmers have had water rights which seem to defy logic – especially now as the state enters into what many are seeing as a 100-year drought.

On one hand, almost all the USA’s fresh vegetables come from California’s Central Valley, along with almonds, grapes, walnuts, and peaches. To produce this abundance, farmers could historically pump as much as they wanted from their wells. On the other hand, California’s aquifers are shrinking as farmers pump water like there is no tomorrow.

Now, state regulators are turning to satellite technology that was once used to count Soviet missile silos during the Cold War to figure out exactly how much water farmers are using and to stabilise the disappearing water table.

What has brought this on has been that although laws have been passed to protect the aquifers, to get farmers to come clean on the number of wells they have and how much water they are pumping has proved to be impossible.

According to an article from NPR, to help regulators calculate water usage, scientists and private companies are now offering a technique that uses images from orbiting satellites. “The days of agricultural anonymity are over,” says Joel Kimmelshue, co-founder of the company Land IQ, which is helping to hone the technique,

This technique involves several steps. The first is figuring out which crops are growing on each field. The satellite images, which are updated almost every week, contain clues: the shade of green, the spacing of vegetation, the time of year the field turns green. Combining those clues, Kimmelshue says, produces a fingerprint of each crop.

Each crop, at a particular point in its life cycle, takes up a predictable amount of water and releases it through its leaves, depending on local weather conditions. Land IQ has set up local monitoring stations to keep track of things like wind speed, heat and humidity, at hundreds of locations. Putting it all together, the company calculates the amount of “evapotranspiration” — the amount of water that the plants are releasing to the air, as well as what’s evaporating from the soil.

That’s different from the amount that farmers are pumping because some irrigation water that’s pumped from the aquifer sinks back into the earth. Because of this, Kimmelshue has convinced officials that it’s more important to regulate water consumption, in the form of evapotranspiration, rather than water pumping.

He’s now selling that data to more than a dozen groundwater regulatory agencies.