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The Simple River-Cleaning Tactics That Big Farms Ignore

In Iowa and elsewhere, runoff from fertilized fields pollutes drinking water and creates dead zones. Yet straightforward solutions exist.

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Iowa is the largest corn producer in the U.S.—and the second largest producer of nitrate pollution in the Mississippi River Basin.


This story was produced in collaboration with the Food & Environment Reporting Network, a nonprofit investigative news organization.

Ione Cleverley wasn’t eager to break up with her tenant, who had been farming 88 acres of her central Iowa land for more than a decade. He was affable and hardworking, but after harvesting his corn and soybeans, the farmer left her fields unplanted. Cleverley had learned that each spring, as the soil warmed and moistened, it released nitrogen—both naturally occurring and left over from the last application of synthetic fertilizer. Rain washed the chemical into her stream, which flows into the Skunk River and thence into the Mississippi.

Along its winding route, nitrogen, which converts to nitrate in water, presents two serious problems. It threatens the health of those who drink it at the tap, and when it reaches the ocean, it hyper-charges the growth of algae and aquatic bacteria, which use up most of the oxygen in the water, leaving it uninhabitable by many other sea creatures. This past summer, the Gulf of Mexico had its largest ever “dead zone”—and the largest of several hundred in the world.

After speaking with a farm consultant about how to stanch her contribution to it, Cleverley met with her tenant. “I told him I wanted him to quit tilling and plant a cover crop this fall”—whether cereal rye, clover or alfalfa, it would soak up excess nitrogen come spring. “He wasn’t too receptive,” Cleverley says, dryly. “He didn’t see the connection with downstream water quality.” Moreover, the chemical company that advised her tenant—and sold him fertilizers and seeds—had warned him that cover crops might reduce his corn and soybean yields, at least at first.

Cleverly wasn’t unsympathetic: She knew that change comes hard to farmers. But she also knew that sowing an alternate crop would eventually pay off with improved soils and higher yields. And so she gave her tenant an ultimatum: Plant a cover crop this fall, or she’d find a farmer who would.

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Bill Stowe, general manager of Des Moines Water Works, stands by the Raccoon River, a major source of the city's drinking water. To make it safe, the Water Works have to remove nitrates that come from farms upstream.


Too Much of a Good Thing

Iowa has some of the richest farmland on the planet; an acre in Cleverley’s region can sell for upwards of $10,000. The state produces more corn than any other in the nation, and its soybean yields are second only to Illinois.

But all this production—abetted by steady applications of nitrogen fertilizer— has taken a serious toll. More than two hundred of Iowa’s community water systems struggle with high nitrate levels, periodically issuing “Do Not Drink” orders. The state is the second-largest contributor of nitrates to the Gulf in the Mississippi River Basin.

The good news is that researchers have a pretty good handle on how to solve Iowa’s water problem. In 2014 the state released a Nutrient Reduction Strategy that calls for slashing nitrate runoff by 41 percent. The plan lists a suite of tools that farmers can use to hit this mark, from applying fertilizer more sparingly—crops take up, on average, only half the nitrogen that’s applied to fields—to planting cover crops, to allowing strips of farmland to revert to unfertilized prairie.

The bad news: These recommended practices are voluntary, and relatively few of Iowa’s 88,000 farmers do them. Many, like Cleverley’s tenant, just don’t see their personal connection to the problem—and that leaves it for others to solve.

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Phosphates running off Ohio farm fields help trigger algae blooms in Lake Erie, which has impacted the water supply of Toledo.


Someone’s Got to Pay

The U.S. Environmental Protection Agency requires utilities to deliver tap water with no more than 10 milligrams of nitrates per liter. Water above this limit can, in infants, inhibit the blood’s capacity to carry oxygen, causing the potentially fatal “blue baby syndrome.” Some studies have linked high nitrate levels with birth defects and, in adults, various cancers and thyroid problems.

Nationwide, utilities spent $4.8 billion to remove nitrates from public drinking water supplies in 2011, the last year for which data are available. The money goes toward energy- and chemical-intensive filtration systems, or toward drilling new wells into cleaner supplies, or toward pumping and blending water from different sources.

“We have a responsibility to provide safe water,” Bill Stowe, general manager of the Des Moines Water Works, says in his sunlit conference room. “High nitrates are a public health risk whether they are consumed by a six-month-old or a 66-year old.” Most consumers don’t care how those nitrates are removed, so long as their water bills don’t rise. But it is far cheaper, on a per pound basis, to keep nitrates from water upstream—on farms, that is—than it is for utilities to remove them downstream.

Stowe may understand these economics better than any utility operator in the nation. Between 1995 and 2014, nitrate concentrations at his utility’s intakes on the Raccoon River exceeded the federal drinking-water standard on at least 1,635 days, or 24 percent of the time. In 2015 the utility spent $1.5 million to strip nitrates from the water, and it was also facing a roughly $15 million bill to revamp the denitrification equipment. “It’s basically been run into the ground with overuse,” Stowe says.

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Ion exchange vessels in the Des Moines Water Works remove nitrate from up to 10 million gallons of water a day. The high cost prompted the Water Works to sue upstream farming districts in 2015.


Fed up, Stowe in 2015 sued those he considered responsible for tainting his water. He targeted three upstream drainage districts, representing more than two thousand farmers, and claimed that perforated pipes underlying their fields, which drain excess rain and snowmelt into ditches and creeks, constitute “point sources” of pollution. As such, he argued, those pipes, known as tiles, should be regulated under the federal Clean Water Act, just like factories spewing chemicals into rivers. (Historically, agriculture has been considered a “nonpoint” source of pollution that is exempt from the Clean Water Act.)

Stowe’s lawsuit was a big deal, on many levels. Drinking water utilities tend to be conservative: They avoid engaging in cutting-edge environmental, public policy, or legal issues. Now, not only was Stowe flamboyantly taking an activist stance, he was also challenging the supremacy of production agriculture in a state widely considered to be controlled by that industry. As former governor Terry Branstand said, shortly after the suit was filed, “Des Moines has declared war on rural Iowa.”

That’s because farmers rely so heavily on fertilizer to boost yield and profits. It’s cheap insurance for expensive seed, and billion-dollar industries have formed around its unbridled use—from fertilizer manufacturers to equipment makers and ag consultants. Stowe’s lawsuit threatened all of that, but it turned out the corn and soybean industry, which poured money into a defense fund, needn’t have worried. This past March, a federal judge dismissed the suit on the grounds that drainage districts have immunity from lawsuits seeking monetary damages. The question of who should be responsible for keeping agricultural pollutants from drinking water remains open.

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Upstream from Des Moines, Rosie Partridge walks through native prairie grasses her family planted in 2010, on land that had been farmed for a century. The 38 acres of grasses now help soak up nitrates running off 520 acres of crops, and the grasses also attract pollinators, Partridge says.


An Uncovered State

Just two hours east of Des Moines, the Cedar River provides drinking water to about 130,000 residents of Cedar Rapids. Nitrate levels in the Cedar and its tributaries often rise above federal limits, just like levels in the Raccoon, but the city solves its problem by blending high-nitrate river water with lower-nitrate water from wells—at least for now.

Climate change is pelting the Midwest with more frequent and intense rainstorms, which wash nutrients from fields into source water. After a 5-inch (13-centimeter) rain in June of 2014, nitrate loading at a study site in the Cedar Rapids watershed shot from an average of 45 tons per day to more than 1,000. By the end of the century, scientists predict that climate change will increase the amount of nitrogen flowing into the Gulf by 24 percent, and that’s not even counting expected increases in acres planted with crops.

To get a grip on the nutrients flowing from fields today, a consortium of local government, industry, and civil society groups has teamed up, as the Middle Cedar Partnership Project, to support farmers willing to try some of the practices laid out in the state’s nutrient reduction strategy. Nick Meier, a former seed dealer who farms roughly a thousand acres about 45 miles upstream from Cedar Rapids, is one of the project’s star ambassadors.

“I feel strongly about conservation,” says Meier, who quit plowing his hilly fields decades ago to control soil erosion. But in the fall of 2014, he took a more radical step and filled his planter with the seeds of cereal rye, a cover crop for which he has yet to find a market. Asked what drove him to this extra labor and hassle, Meier is unequivocal: “I didn’t want to be regulated by the government.” Better to voluntarily reduce nitrogen pollution, he figured, than to suffer a government crackdown.

Cover crops can reduce nitrogen runoff by 30 percent, but in 2016 Iowa farmers planted them on less than three percent of the state’s cropped land. The state strategy aims for more than half. According to one analysis, 60 percent of Iowa farmers quit growing cover crops after government aid—usually $25 an acre for just one year—ends. “There is no proven economic benefit [to landowners] for taking nitrates out of the water,” says Dean Stock, a farmer and elected supervisor in Sac County, which was targeted by Bill Stowe’s suit.

In fact, cover crops have been shown to reduce the need for fertilizer. And after first dampening corn yields, as Cleverley’s tenant feared, they eventually increase yields. All that provides economic benefits to the farmer. But cover crops can be tricky to implement and manage. For example, as spring rains get more intense, farmers have a shorter window to terminate a cover crop—by killing it with an herbicide or crushing it with a roller—in time to plant their cash crop.

“The learning curve for these in-field practices can be steep,” acknowledges Nick Ohde, of Practical Farmers of Iowa, which promotes and teaches cover cropping. “If you’re making money as is, then change is problematic. You’re not going to see any benefits if these practices aren’t executed properly.”

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Nick Meier, a farmer in La Porte City, Iowa, drives between a corn field and a buffer strip that filters the runoff from the field, reducing the flow of nitrates into Miller Creek.


The Power of the Prairie

There are plenty of alternatives to cover-cropping, however. On a sunny summer morning, Meier drives his all-terrain vehicle past a blue-green field of bushy soybean plants and parks atop a mowed rectangle. Right under our feet, he explains, a six-foot-deep bunker stuffed with woodchips is filtering runoff from a 60-acre field underlain with drainage pipes.

Microbes in the woodchips reduce the water’s nitrate concentration by 43 percent, converting it to inert nitrogen gas, the stuff of the air around us. Meier seems delighted with his denitrifying bioreactor, as the gizmo is called: It functions properly, it robs him of very little cultivatable space, and it was funded by a state environmental program.

Keen to show off another tool promoted by the Middle Cedar Partnership Project, Meier hops back onto the Gator, zips across a county road and past a field of eye-high corn. “This is a saturated buffer,” he says, gesturing toward a 70-foot wide strip of native grasses and wildflowers that hugs a 1,200-foot stretch of Miller Creek. As tiles under the corn field collect water, then distribute this flow into the buffer, the prairie plants’ deep and extensive roots consume up to half the nitrates in it, releasing cleaner water to the creek. A saturated buffer costs about a third of a bioreactor, and it provides habitat for pollinators and other creatures.

Elsewhere in the state, a smattering of farmers are trying other techniques for capturing nitrate—collecting it in engineered wetlands on their soggier fields, for example, or in silted-in oxbow river bends excavated to hold more water. But Iowa State researchers say the single best thing that farmers could do to improve Iowa’s water quality is to plant prairie grasses on ten percent of their land, in buffers like Meier’s or in strips across the fields.

The problem is that very few farmers volunteer to retire cropland—not when grain prices are high, and not when grain prices are low. As Stowe says, “There’s a lot of talk about volunteerism and conservation practices. But in the real world, the play is always for greater productivity and greater profit.”

Unfortunately, says Anne Weir Schechinger, a senior economics analyst for the Environmental Working Group, “It’s the farmers polluting the most who are the least likely to adopt those methods.” Most farmers, if they adopt a conservation tool at all, opt for one that’s least disruptive to their practice: tweaking the timing and application rate of fertilizer. That cuts nitrate loss, at best, by just 10 percent.

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Two cows graze on an increasingly rare bit of pasture in Iowa. One of the most effective solutions to agricultural pollution would be to return a fraction of the land now planted with corn and soybeans to pasture and prairie.


Exceptional Farmers

The various conservation practices “do work,” says Art Cullen, who won a Pulitzer Prize in 2017 for his fierce editorializing against industrial agriculture in The Storm Lake Times, published about a hundred miles northwest of Des Moines. “But the Raccoon River is imperiled, and a bioreactor here and a wetland there is just a drop in the bucket. It’s trivial compared to what’s needed. We’ve been subsidizing conservation since the Dust Bowl, and water quality is only getting worse.”

When it comes to polluting the air and the water, agriculture has, to some extent, gotten a pass in this country. No one wants to stick it to a farmer. In the current political climate, there seems little prospect of increased government regulation of nutrient runoff—yet voluntary measures clearly haven’t cut it so far. If nothing else, the Des Moines Water Works suit has energized public discussion of the question: Who will pay to keep nitrates out of our rivers?

The Iowa Farm Bureau, for its part, insists farmers are stepping up; they just need more time. “The problem was a century in the making,” says the bureau’s Laurie Johns. “Farmers need more time to adopt these strategies, they need more incentives and more knowledge.”

In November, the Iowa Department of Agriculture implemented a small policy fix, promoted by Practical Farmers of Iowa and others: It now offers a $5 per acre rebate on crop insurance to farmers who plant new acres with cover crops, which have been shown to reduce insurance claims. Other groups suggest tying federal farm subsidies to measurable nitrate reductions. Bill Stowe—aligned with some small-government groups—insists farmers alone should shoulder nitrate-reduction costs. “Iowa producers are already getting $1 billion a year from the USDA,” he says in a tone of outrage.

Market pressures could help. Roughly half of Iowa’s corn and 98 percent of its soybeans feed livestock, much of which is consumed in China. (Most of the rest of Iowa’s corn feeds ethanol plants.) Large companies along that food chain have lately started trying to influence how their raw ingredients are grown.

For example, Smithfield Foods, in partnership with the Environmental Defense Fund, is seeking to source more of its pigs’ corn and soybeans from geographic areas in Iowa—not individual farms—that have shown improvement in reducing nutrient runoff. “These companies want brand-level recognition for their efforts,” Suzy Friedman, EDF’s senior director of agricultural sustainability, says. “They want to say that [they] are good corporate stewards.”

But figuring out the best way to support farmers as land stewards is a complicated proposition. Sixty percent of Iowa farmland is owned by absentee landlords and rented on one-year contracts, which leaves tenants with little incentive to invest in the land’s long-term health. Thankfully, there are a handful of land owners brave enough to shoulder some risk for the greater good.

After Ione Cleverley presented her tenant with a cover-crop ultimatum, this past July, their relationship grew tense. But together they attended several field demonstrations and information sessions on cover cropping. “He still rejects those practices,” Cleverley reports, “but I’m more convinced than ever that it’s the way to go. If you own land, it’s your responsibility to take the best care of it.”

Despite his skepticism, Cleverley’s tenant did, eventually, agree to try a cover crop, but by then it was too late to apply for funding from the USDA. And so Cleverly decided to kick in half the cost of the cereal rye and radish seed herself.

“We’re starting slow, just on the bean ground this year,” she says. “I really don’t want this to fail.”

Follow Elizabeth Royte on Twitter.

An earlier version of this story misstated the U.S. EPA drinking water standard for nitrates. It is 10 milligrams per liter, not 10 micrograms.