Tom Philpott

How the Midwest's Corn Farms Are Cooking the Planet

| Wed Aug. 12, 2015 6:00 AM EDT

I've been thinking a lot recently about how fertilizer from the Midwest's big corn farms seeps into streams and causes trouble—fouling water supplies in Columbus, Toledo, Des Moines, and 60 other towns in Iowa, and generating a Connecticut-sized dead zone at the heart of the continental United States' most productive fishery, the Gulf of Mexico. (Farms in the region also plant soybeans, but corn is by far the bigger fertilizer user.) But there's another way the Corn Belt's fertilizer habit damages a common resource: by releasing nitrous oxide (N2O), a greenhouse gas with nearly 300 times the heat-trapping power of carbon dioxide.

Scientists had been undercounting nitrous oxide emission in the Corn Belt by about 25 gigagrams annually—the equivalent of about 1.6 million cars on the road.

It turns out that the region's farms are likely generating much more nitrous oxide than scientists previously thought, according to a new peer-reviewed study by a team of researchers from the University of Minnesota, Yale, and the US Department of Agriculture.

Scientists had assumed that most nitrous oxide emissions from farming occurred at the soil level—some of the nitrogen fertilizer applied onto farmland vaporizes into nitrous oxide. But as citizens of Des Moines, Columbus, and the Gulf coast know well, nitrogen fertilizer doesn't stay in soil; a portion of it leaches into streams. And some of that escaped nitrogen, too, transforms into nitrous oxide.

To measure how much, the team, led by University of Minnesota researcher Pete Turner measured N2O emissions at 19 streams over a two-year period in ag-intensive southeastern Minnesota. They found that standard greenhouse gas emission measures, such as those used by the Intergovernmental Panel on Climate Change (IPCC), have been undercounting these "riverine" emission sources by a factor of nine; and overall N2O emissions from the area are underestimated by about 40 percent.

While they only took measurements in one small part of the US Midwest, the researchers write that other regions of the globe have similar conditions: large swaths of land dominated by fertilizer-intensive farming. Such areas include the rest of the US Corn Belt plus parts of China, Europe, and India. These industrial-scale farming regions, which together make up a landmass of about 580 million acres (nearly six times the size of California), are the globe's most potent sources of nitrous oxide, and we're likely drastically undercounting their total emissions, the study suggests.

Altogether, the paper estimates, typical assessments undercount nitrous oxide emission in the Corn Belt by about 25 gigagrams annually. According to my back-of-the-envelope calculation, that's the equivalent of about 1.6 million cars on the road over a year (assuming that 1 gram of nitrous oxide has the heat-trapping power of about 300 grams of carbon dioxide, and that the average passenger car burns through 4.75 metric tons of CO2 equivalent each year).

So efforts to rein in fertilizer runoff in the Corn Belt aren't just about cleaner water and lower filtration bills for the area's urban residents, or a more vibrant Gulf of Mexico fishery. They're also about stabilizing the climate. Back in 2013, I profiled Ohio farmer David Brandt, who has innovated a method for churning out bumper harvests using much less fertilizer, leading to much less runoff.

Advertise on MotherJones.com

Death Rates From Alzheimer's and Other Cognitive Diseases Are Spiking

| Tue Aug. 11, 2015 6:00 AM EDT

The good news from this new mortality study is that US cancer and cardiovascular death rates have dropped over the past quarter-century. The bad news is that death rates from neurological diseases like Alzheimer's have soared—and Americans are much likelier to die from these diseases than their peers in most other developed countries.

To get their results, researchers from Bournemouth University in the United Kingdom looked at World Health Organization mortality statistics for 21 developed nations, comparing the 1989–91 period with the 2008–10 time frame.

For adults between the ages of 55 and 74, overall neurological death rates barely budged, rising 2 percent for men and 1 percent for women. But here in the United States, things got dramatically worse—death rates from dementia and other brain-related illnesses like Parkinson's disease and motor neuron disease spiked, jumping 82 percent for men and 48 percent for women. American men and women in this age group now have the second-highest neurological death rates in the developed world, behind Finland. In the earlier period, they ranked 17th and 11th, respectively.

For the elderly (aged 75 and up), the situation is even more dire. Overall, the neuro-related death rate jumped 114 percent for men and 185 percent for women. Here in the United States, elderly death rates from neurological causes leapt more than twofold (368 percent) for men and more than fivefold (663 percent) for women. Neurological causes now kill more elderly American women than cancer does.

Over the same time frame, death rates from cancer and cardiovascular disease dropped, both in the developed world overall and in the United States in particular. For 55- to 74-year-olds, male cancer death rates fell 20 percent overall, and US rates dropped 36 percent. Women in that age group showed a 16 percent reduction in cancer deaths throughout the developed world and an 18 percent reduction in the United States. Similar trends held true for heart-related diseases.

When you look only at Alzheimer's isolated from other neurological diseases, you'll also see a relative spike in deaths, as this chart from a 2015 report by the US-based Alzheimer's Association shows.

Alzheimer's Association

What gives? Why are so many Americans so much more at risking of dying of neurological diseases like Alzheimer's, even as other threats recede? And in the developed world as a whole, why are neurological-related death rates rising for people over the age of 75?

One obvious factor is that medical science has come up with all sorts of treatments to prolong the lives of people with cancer and cardiovascular conditions, while treatments for Alzheimer's have proven elusive. It could be simply that Alzheimer's and other neurological diseases are "diseases of the elderly"—that our brains are doomed to decline past a certain age, and more and more people are surviving cancer and heart disease only to "develop diseases that they would not have lived long enough to have acquired in previous times," as the authors of the UK study put it. But that probably doesn’t fully explain the findings, particularly since some countries, like the United States, have fared so much worse than others.

The study's authors don't speculate much on what's driving the trends they identified; they suggest that lifestyle factors might play a role. Heather Snyder, director of medical and scientific relations at the Alzheimer's Association, told me that there are significant but still-inconclusive links between cognitive decline and diet-related maladies like obesity and diabetes. A 2015 paper she co-authored delivers a broad state-of-the-science view on the relationship. Here's a summary.

"Summary of the evidence on modifiable risk factors for cognitive decline and dementia: A population-based perspective," Baumgartan, et al.

Indeed, there's mounting evidence that high-sugar diets contribute to cognitive decline, a trend I wrote about here. There's also compelling evidence that air pollution might be a trigger of neurodegenerative diseases, as Aaron Reuben's recent Mother Jones blockbuster shows.

Coca-Cola to World: Don't Stop Swilling Sugary Drinks, Just Exercise!

| Mon Aug. 10, 2015 6:32 PM EDT

Stunningly, one-third of American adults have a condition called metabolic syndrome, defined as "a cluster of major cardiovascular risk factors related to overweight/obesity and insulin resistance." People with metabolic syndrome are twice as likely to develop heart disease as people without it, and five times as likely to develop full-blown type II diabetes. Meanwhile, a growing body of research links insulin resistance with Alzheimer's and other forms of cognitive decline.

There's a solid consensus that two things need to happen to reverse this budding calamity: People need to eat better—less hyperprocessed, sugar-laden fare—and exercise more.

Now, if you were in the business of selling sweet beverages—ones that contain about nine teaspoons of sugar per 12-ounce serving—you'd have an interest in suggesting that maybe diet's not that big of an issue, after all. Instead of cutting down on soda, why not just take an extra walk around the block?

According to this New York Times exposé, Coca-Cola, the globe's biggest purveyor of sugary drinks, invested $1.5 million last year to launch the Global Energy Balance Network, which, the Times reports, "promotes the argument that weight-conscious Americans are overly fixated on how much they eat and drink while not paying enough attention to exercise."

The beverage maker has also invested "close to $4 million in funding for various projects spearheaded by two prominent US health academics who serve on GEBN's executive committee, the Times adds. One of them, University of South Carolina health professor Steven Blair, is featured in the above video insisting that "most of the focus in the popular media and in the scientific press is, 'Oh they're eating too much, eating too much, eating too much'—blaming fast food, blaming sugary drinks, and so on [for rising obesity rates]… And there's really virtually no compelling evidence that that, in fact, is the cause."

Meanwhile, the World Health Organization recommends holding added sugar consumption to about 25 grams (six teaspoons) per day—meaning a single Coke (nine teaspoons of sugar) will take you 50 percent over its daily recommendation. My colleague Maddie Oatman has a great piece on just how easy it is to catapult over the six-teaspoon limit in the sugar-happy US food environment.

Now, Coke's high-dollar drumbeating about how sugary drinks don't matter much may be nefarious, but it’s also sort of desperate. People are wising up—soda sales have fallen for 10 straight years.

The Big-Ag-Fueled Algae Bloom That Won't Leave Toledo's Water Supply Alone

| Wed Aug. 5, 2015 6:05 AM EDT
A vast Lake Erie algae bloom returns, captured by a NASA satelite on July 28.

The citizens of Toledo, Ohio, have embarked upon their new summer ritual: stocking up on bottled water. For the second straight year, an enormous algae bloom has settled upon Lake Erie, generating nasty toxins right where the city of 400,000 draws its tap water.

It's a kind of throwback to Toledo's postwar heyday, when the Rust Belt's booming factories deposited phosphorus-laced wastewater into streams that made their way into Lake Erie, feeding algae growths that rival today's in size. But after the decline of heavy industry and the advent of the Clean Water Act, there's a new main source of algae-feeding phosphorus into the beleaguered lake: fertilizer runoff from industrial-scale corn and soybean farms. (Background here.) 

A Federal Judge Just Struck Down Idaho’s Law Against Secretly Videotaping Animal Abuse on Farms

| Tue Aug. 4, 2015 6:34 PM EDT

Captured by undercover investigators and released in 2012, the above video depicts a disturbing scene inside a large Idaho dairy facility. We see workers committing various acts of violence against cows: kicking and punching them, beating them with rods, twisting their tails, and, most graphically, wrapping a chain around the neck of a downed cow and dragging it with a tractor. The exposed dairy promptly fired five workers in the aftermath, but behind the scenes, Idaho's $6.6 billion dairy industry quietly began working with its friends in the state legislature on a different response, according to US District Court Judge B. Lynn Winmill.

In a decision released Monday, Winmill wrote that the Idaho Dairymen's Association "responded to the negative publicity by drafting and sponsoring" a bill that criminalizes the "types of undercover investigations that exposed the [violent] activities." Known as ag gag legislation—check out Ted Genoways' must-read Mother Jones piece on the phenomenon—it sailed through the Idaho Legislature and became a law in 2014.

Winmill declared the law unconstitutional in his decision, stating that its only purpose is to "limit and punish those who speak out on topics relating to the agricultural industry, striking at the heart of important First Amendment values." Moreover, the judge ruled, the law violates the Equal Protection Clause of the 14th Amendment, "as well as preemption claims under three different federal statutes." Ouch.

According to Food Safety News, seven other states have similar ag gag laws on the books. "This ruling is so clear, so definitive, so sweeping," Leslie Brueckner, senior attorney for Public Justice (co-counsel for the plaintiffs in the case), told ThinkProgress. "We couldn't ask for a better building block in terms of striking these laws down in other states."

Fumes From Iowa Hog-Manure Pit Kill Father and Son

| Thu Jul. 30, 2015 6:56 PM EDT
Hogs in a concentrated animal feeding operation (CAFO). Note the slatted floor.

Here's another reason why Americans should think twice about how the United States is emerging as the globe's hog farm: concentrating thousands of hogs in one place means concentrating huge amounts of their shit, too; and that shit puts off gases that are so noxious that they can kill people who work near them. Think I'm exaggerating? Get this, from the Des Moines Register:

A father and his son who were so close that they were “like glue” were killed Saturday by noxious fumes from a northwest Iowa hog manure pit—the second father and son in the Midwest to die of poisonous manure pit gases this month.

These large, indoor facilities confine hogs above their own waste on a slatted floor—the waste falls through the slats and collects in a pit below. An incredibly putrid aroma—I've smelled it—shrouds these facilities. The air contains hydrogen sulfide, methane, ammonia, carbon dioxide, and volatile organic compounds. Hogs can live above these poison-gas cesspools because giant fans keep the air moving. But when something goes wrong beneath the slats, workers have to venture into places where there is no effective ventilation. And that's what happened on this Iowa hog farm, to heartbreaking effect.

The two were repairing a pump at a hog confinement when a piece of equipment they were using fell into the manure pit, Wempen [a relative] said. Austin Opheim went into the pit first to retrieve the equipment, and his father followed him after realizing his son had been overcome by gases, Wempen said. ...  “(Gene) was carrying Austin on his back and bringing him up and he got almost to the top and he got overcome, and down they went,” she said.

An eerily similar father-son tragedy occurred in Wisconsin earlier in July.

Such disasters can usually be averted by donning proper breathing equipment when venturing beneath the slats. But in recent years, Midwestern hog facilities have been beset by a mysterious foam that settles at the surface of manure pits, which creates a buildup of volatile gases that that has caused many explosions. Back in June, two workers at a Minnesota hog farm died in a fire that erupted after they had been cleaning the slats of an empty hog facility—apparently the result of "power-washing activities bursting the foam bubbles in the manure pit" below. And last year, reports the trade journal Pork Network, a "similar fire in Iowa severely burned Leon Sheets, a past president of the Iowa Pork Producers Association, as he power-washed one of his hog barns."

Advertise on MotherJones.com

Watch What It's Like to Live Amidst Industrial Hog Farms

| Wed Jul. 29, 2015 1:33 PM EDT

As I showed recently, the United States is emerging as the world's hog farm—the country where massive foreign meat companies like Brazil's JBS and China's WH Group (formerly Shuanghui) alight when they want to take advantage of rising global demand for pork. (If JBS's recent deal to buy Cargill's US hog operations goes through, JBS and WH Group together will slaughter 45 percent of hogs grown in the United States.)

A recent piece by Lily Kuo in Quartz (companion video above) documents what our status as the world's source of cheap pork means for the people who live in industrial-hog country. It focuses on Duplin County in eastern North Carolina, which houses "about 530 hog operations with capacity for over 2 million pigs ….one of the highest concentrations of large, tightly-controlled indoor hog operations, also known as CAFOs (concentrated animal feeding operations) in the world." In Duplin, "hogs outnumber humans almost 32 to 1," Kuo reports. And that means living amid lots and lots of pig shit—the county's hog facilities generate twice the annual waste of the entire population of New York City.

As I've shown before, the hog industry doesn't build wealth in the communities where it operates—the opposite, in fact. "Almost a quarter of the population lives below the poverty line, making Duplin County one of the poorest counties in North Carolina," Kuo writes. "It is also disproportionately black and Hispanic compared to the rest of the state."

Scientists Say Supposedly Miraculous Ingredients in Weed Killers Don't Actually Work

| Wed Jul. 29, 2015 6:00 AM EDT

Before pesticides go from the laboratory to the farm field, they have to first be vetted by the Environmental Protection Agency. But they're commonly mixed—sometimes by the pesticide manufacturers, sometimes by the farmers themselves—with substances called adjuvants that boost their effectiveness (to spread more evenly on a plant's leaf in the case of insecticides, or to penetrate a plant's outer layer, allowing herbicides to effectively kill weeds). Despite their ubiquity, adjuvants aren't vetted by the EPA at all; they're considered "inert" ingredients.

Despite their ubiquity, adjuvants aren't vetted by the EPA at all; they're considered "inert" ingredients.

I first wrote about them last year, when adjuvants mixed with fungicides came under suspicion of triggering a large bee die-off during California's almond bloom. Recently, an eye-popping article by Purdue weed scientists in the trade journal Ag Professional brought them to my attention again. The piece illustrates the unregulated, Wild West nature of these additives.

In the article, the authors note that two companies are hotly promoting adjuvant products as a kind of miracle cure for the ever-increasing scourge of herbicide-resistant weeds. That's a bold claim, given that resistant weeds now plague more than 60 million acres of farmland.

Odder still, both companies attribute their products' effectiveness to nanotechnology, a controversial, lightly regulated engineering tool that leverages the fact that when you break common substances into tiny particles, they behave in radically different ways than they do at normal sizes. Nanoparticles are so tiny, their size is measured in nanometers—a billionth of a meter. (A human hair is about 80,000 nanometers thick; nanoparticles typically measure in at less than 100 nanometers.)

An adjuvant called ChemXcel, from a Minnesota-based company called C&R Enterprises, claims to "kill herbicide-resistant weeds" when mixed with common herbicides like glyphosate. It works its magic through "patented, proprietary nano-drivers" that "alter the glyphosate chemistry" by "coating the individual DNA gene-sequencing molecules internally," the company claims.

Then there's NanoRevolution 2.0, marketed by a company called Max Systems. When goosed with a bit of NanoRevolution 2.0, the company states, "the herbicide 'piggybacks' onto the nano particles as they penetrate the leaf structure, carrying the herbicide directly to the root system for a faster enhanced plant absorption of herbicides even on hard-to-control weeds."

Taken aback by the claims and the use of nanotech, I contacted the EPA to see what, if anything, the agency had to say. "While we are not familiar with those particular products, EPA has jurisdiction over substances that meet the definition of pesticides, that is, claims are made for them that they kill, repel, prevent, or otherwise control pests," an Environmental Protection Agency spokesperson wrote in an email. "As long as pesticide adjuvant products don’t make pesticidal claims, they are not pesticides and the components of adjuvants are therefore not pesticide ingredients (either active or inert)"—and thus not subject to EPA vetting. Manufacturers aren't even required to list ingredients in adjuvants.

Here, for example, is Max Systems describes the ingredients of NanoRevolution 2.0:

Purdue weed scientist Bill Johnson, who co-authored the Ag Professional piece, says he and his team found that neither of these "nano" products work as advertised. "I began getting calls about reports that these things were being pushed in northern Indiana, and I thought, we need to prove or disprove the claims."

Carbon nanotubes  are one of the most controversial nanoparticles—often compared to asbestos for their ability to lodge into the lungs and cause trouble when they're breathed in.

So he and colleagues tested the products on a weed patch known to be glyphosate resistant, mixing them with glyphosate at levels recommended by the manufactures. The results, published in the trade journal Ag Professional, were underwhelming. On its own, Roundup (Monsanto's version of the glyphosate herbicide) killed just 13.8 percent of weeds. Mixed with ChemXcel, it killed 15 percent of weeds, while the called NanoRevolution 2.0/Roundup mix killed 18 percent of weeds.

Johnson explained that herbicides are always mixed with adjuvants—they're typically needed to help the herbicide penetrate a weed's outer layer. But these particular ones perform no better or worse than conventional adjuvants on the market. But they don't come anywhere near to solving the herbicide-resistance problem, as the companies claim to do.

C.J. Mannenga, co owner of C&R Enterprises, pushed back strongly on Johnson's assessment and challenged his results. "We know our product works," he said. "We've shown it in Georgia, we've shown in Ohio, we've shown it in Missouri, we've shown it in Iowa," he said. When we spoke Tuesday afternoon, Mannenga told me that he was in Osborne, Kansas, about to "meet with a major [agrichemical] distributor" who is "extremely interested in the product ... I'm going to do a demonstration to show them indeed it does work."

While the product's information sheet doesn't list its active ingredients, he readily revealed it to me: "it's just carbon nanotubes."

Carbon nanotubes  are one of the most controversial nanoparticles—often compared to asbestos for their ability to lodge into the lungs and cause trouble when they're breathed in. This 2014 assessment by researchers at the University of Massachusetts at Lowell is hardly comforting:

Though ecosystem impacts remain understudied across the CNT [carbon nanotube] lifecycle, evidence suggests that some aquatic organisms may be at risk. While there have been significant advances in the regulation of CNTs in recent years, the lack of attention to the potential carcinogenic effects of these nanomaterials means that current efforts may provide a false sense of security.

Meanwhile, no one employed by NanoRevolution 2.0 maker Max Systems returned my request for comment.

Enjoy Your Romaine—While It Lasts

| Wed Jul. 22, 2015 6:00 AM EDT

The mighty Central Valley hogs the headlines, but California's Salinas Valley is an agricultural behemoth, too. A rifle-shaped slice of land jutting between two mountain ranges just south of Monterey Bay off the state's central coast, it's home to farms that churn out nearly two-thirds of the salad greens and half of the broccoli grown in the United States. Its leafy-green dominance has earned it the nickname "the salad bowl of the world." And while the Central Valley's farm economy reels under the strain of drought—it's expected to sustain close to $2.7 billion worth of drought-related losses—Salinas farms are operating on all cylinders, reports the San Jose Mercury News.

As the Salinas Valley's freshwater vanishes and dips below sea level, seawater from the coast seeps in to take its place—which isn't good news for crops.

What gives? It all comes down to water sources. In normal years, Central Valley farmers draw more than half of their water from the vast, publicly funded irrigation projects that carry snow melt from the Sierra Nevada mountain range, with underground aquifers providing the rest. With the Sierra Nevada water essentially gone—snows have been minuscule the past four winters—the region's farmers have been scrambling to tap as much underground water as possible. But they can't make up for the massive shortfall, so they're fallowing large tracts of land (not almonds and pistachios, though—they keep expanding) and laying off thousands of farm workers.

Meanwhile, farmers in the Salinas Valley rely nearly 100 percent on underground aquifers, drought or no. And that means "the drought's a marvelous time to grow stuff, if you have the water under full control, because you can take advantage of predictable weather and strong prices," Richard Howitt, ag economist at UC Davis, tells the Mercury News. (Prices are strong because drought-stricken farms in the Central Valley have cut back on production of non-permanent crops, reducing supply.)

But all isn't well under those fields teeming with ripe vegetables and hustling farm workers. For one thing, decades of heavy nitrogen-fertilizer use has left underground water widely contaminated with high levels of nitrate, which isn't good for the people who rely on it for drinking water, because nitrate can reduce the blood's ability to carry oxygen and has been linked to elevated rates of birth defects and cancers of the ovaries and thyroid. A US Geological Survey spreadsheet (pdf version)—part of a recent USGS study of California's water quality I wrote about here—shows that 20 percent of the region's wells (see row "SCR-Salinas") have over-the-legal–limit nitrate levels.

Worse, the region's aquifers, the lifeblood of its $8.2 billion ag economy and sole source of drinking water, are in a "state of long-term overdraft," a 2014 assessment from the California Water Foundation found. The paper notes that when the California Department of Water Resources released its ranking of the state's aquifers based on those that are under the most stress, all eight of the Salinas Valley's aquifers made the list of most-stressed basins. And the state's number-one most-stressed aquifer of all doesn't lie under some vast, arid pistachio grove in the southern Central Valley; rather, it's the Salinas' East Side Aquifer.

The problem isn't just that the area's farms—which account for 90 percent of its water use—are sucking out billions of gallons more water from aquifers every year than is naturally replenished, as this 2014 report prepared for Monterey County found. It's also that as the freshwater vanishes and dips below sea level, seawater from the coast seeps in to take its place—not good, because crops don't grow well in salty water.

So, while the drought has so far caused few immediate problems for Salinas Valley farmers, they're standing over a ticking time bomb—and so are the consumers who rely on them for salad greens and other fruits and veggies: that is to say, Americans. "The irony is that in the short run, the Central Coast farmers are better off," UC-Davis ag economist Howitt told the Mercury News. "But in the long run they've got to get their [water] credit card under control."

California Drinking Water: Not Just Vanishing, But Also Widely Contaminated

| Mon Jul. 20, 2015 6:00 AM EDT

In normal years, California residents get about 30 percent of their drinking water from underground aquifers. And in droughts like the current one—with sources like snowmelt from the Sierra Nevada mountains virtually non-existent—groundwater supplies two-thirds of our most populous state's water needs. So it's sobering news that about 20 percent of the groundwater that Californians rely on to keep their taps flowing carries high concentrations of contaminants like arsenic, uranium, and nitrate.

When farms sprouted up, they mobilized the once-stable uranium naturally present in the soil, and the toxic element leached into groundwater.

That's the conclusion of a ten-year US Geological Survey study of 11,000 public-water wells across the state. The researchers tested the wells for a variety of contaminants, looking for levels above thresholds set by the Environmental Protection Agency and/or the California State Water Resources Board.

Interestingly, naturally occurring trace elements like arsenic, manganese, and uranium turned up at high levels much more commonly than did agriculture-related chemicals like nitrate.

In the ag-heavy San Joaquin Valley (the Central Valley's Southern half), for example, you might expect plenty of nitrate in the water, because of heavy reliance on nitrogen fertilizers. Over the limit of 10 parts per million in water, nitrate can impede the blood's ability to carry oxygen and has been linked to elevated rates of birth defects and cancers of the ovaries and thyroid. But while 4.9 percent of wells in the San Joaquin turned up over legal nitrate thresholds, arsenic (over legal limits in 11.2 percent of wells) and uranium (7.4 percent)—neither of which are used in farming—were more common.

But in the case of uranium—which heightens the risk of kidney trouble and cancer when consumed in water over long periods—agriculture isn't off the hook. Kenneth Belitz, the study's lead author and chief of the USGS's National Water Quality Assessment Program, explains that before irrigation, the arid San Joaquin landscape supported very little vegetation, and the naturally occurring uranium in the landscape was relatively stable. But as farms sprouted up, irrigation water reacted with carbon dioxide from now-abundant plant roots to "mobilize" the uranium, pushing it downward at the rate of 5 to ten feet per year and eventually into the water table.

Conversely, some of the regions with highest nitrate levels are former ag areas that are now suburban, Belitz says: northern California's Livermore Valley and southern California's Santa Ana basin. That's because nitrates, too, move through the soil strata at a rate of five to ten feet per year, and take years to accumulate in underground aquifers.

And that means that today's ag-centric areas, including the San Joaquin Valley, could be slowly building up nitrate levels year by year that could lead to much higher nitrate levels in well water in coming decades, Belitz says.

For California residents and policymakers, the reports adds another distressing data point to the current water crisis. The fossil record and climate models suggest that precipitation levels will likely drop significantly compared to 20th century norms going forward, according to UC Berkeley paleoclimatologist B. Lynn Ingram—meaning an ever-growing reliance on groundwater for both farms and residents. Meanwhile, NASA research shows that this increasingly important resource is being drawn down at a much faster pace than it's being replenished. And this latest USGS study suggests that the state's precious, vanishing groundwater supply is widely contaminated. It's enough to make you want to open a bottle of the state's famous wine.