A new report published in the journal Nature Climate Change by NASA scientist James Famiglietti paints a grim picture of water conditions in California, our country's breadbasket. Americans get around a third of our produce from California, but that number doesn't really explain how dependent we are on California farms. Here's a quick list of some foods and the percentage consumed by Americans that is grown in California (or rather were, these numbers are from 2007):

Pomegranates- 100 percent

Artichokes- 99 percent

Kiwi- 97 percent

Olives- 96 percent

Plumes and prunes- 94 percent

Avocados- 90 percent

Nectarines- 89 percent

Garlic- 85 percent

Grapes- 82 percent

Lemons- 79 percent

Tomatoes- 76 percent

Strawberries- 59 percent

The full list of what California farms produce is long and frightening. If we lose California agriculture, food will get a lot more expensive and possibly become completely unavailable, at least seasonally.

Famiglietti's report is unfortunately behind a paywall, but has been nicely summarized by Tom Philpott over at Grist. According to that update, California groundwater is being pumped out aquifers at a rate far greater than the natural rate of replenishment. The water is being used by municipalities to feed growing towns and cities, and by giant farms in the Central Valley, home to most of the state's agriculture.

California's long-running drought is a major driver of the rise in aquifer pumping. It's a simple fact: people need water. If they can't get water from a lake or river, they're going to get it from a well. While the state's surface water is relatively well protected, it's the wild west right now in terms of aquifers. If you own land and drill a well, you can pump as much water as you'd like, pretty much. Gov. Jerry Brown recently signed legislation into law that will require some of level local oversight of aquifer pumping, but it's a slow-moving piece of law that doesn't even require plans to be drawn up until 2020 or 2022.

It's certainly a good and necessary step to impose some control over groundwater pumping, but Famiglietti's report tells the story of an aquifer system already in deep distress. This map shows the rapid drop in aquifer levels over the last few years. The chart shows the deepest red as 160 millimeters, or a little more than six inches. A six inch state-wide drop in a state as large as California in just a couple of years is no joke.

Map showing aquifer levels in California

Graphic: Nature.com

The thing about aquifer water is that it is irreplaceable, more or less. The water that is now being pumped in the Central Valley to grow your carrots took thousands of years to trickle down through cracks and pores of the Earth. So while you could say that aquifer water is replaceable on the timescale of a redwood tree, sadly the same is not true of a human. Here's a good image, via Wikipedia, that explains how it works:

Aquifer diagram

Graphic: Wikipedia

Central Valley farmers who grew up with 200-foot wells are finding now that 1,000-foot wells aren't deep enough to hit the retreating water table. Drilling crews have months-long waiting lists from desperate farmers looking at productive fields that will turn to dust without irrigation.

The danger of the situation is in the simple economics. As the drought drags on and there is less surface water available, the aquifer water will be more valuable. This will drive even more drilling, driving down water levels at a far more frenzied level than even today. The new legislation will help some, but it also leaves lots of room for manipulation by well-monied water interests. The local control imposed by the legislature sounds good from a small-government point of view but it also makes it a lot easier for big water pumpers to influence local regulations to allow their continued pumping.

So what does California's water problems mean for you? In the short term, expect to pay more at the grocery store for the raw produce grown in the state as well as any processed foods that use them as ingredients. Unfortunately a similar plunder of irreplaceable aquifer water is happening in the middle of the country as corn and soybean farmers compete with cities and towns to see who can suck out the most water from the Ogallala Aquifer, so it's likely we'll see a similar rise in the price of corn and corn-based foods (which is basically everything in the grocery store). Every year that the drought continues is likely to mean grocery bills will rise well above inflation. To get an idea of how good we are at managing our aquifer resources, check out this map showing declining aquifer levels around the country. The blue line at the bottom of the chart is the Ogallala Aquifer, while the yellow line shows the water levels of the Central Valley.

Water aquifer levels

Graphic: Nature.com

In the long term, we could be in for a wholesale shift in how our country produces food. Agriculture would, out of necessity, need to become more localized throughout the nation as California output dwindled. I don't know enough about farming to postulate about how much of California's output we'd actually be able to shift to other states, so I'll just leave with the hopeful thought that we would be able to find our way out of this mess we're making for ourselves. We'd better — I don't want to give up eating almonds and kiwis.

Are you on TwitterFollow me (@sheagunther) there, I give good tweets. And if you really like my writing, you can join my Facebook page and visit my homepage.

Related on MNN: