This story is part of a series by the Center for Public Integrity, Grist and The World about how our overuse of fertilizer harms the climate and endangers the public.

If you want to clean up the largest pollution spill in the country, one unaltered by decades of work and billions of dollars, you need to spend a lot of time making tiny measurements. Most of them will only confirm the depressing trend: More and more contaminants are winding their way from farms into rivers and streams.

But in one small watershed in northern Indiana, those measurements have revealed an undeniable improvement in one of the most stubborn environmental crises in the world.

On a foggy November morning, between gently rolling fields, Jennifer Tank, a biology professor at the University of Notre Dame, and two of her graduate students dressed in waders lowered themselves into the Shatto ditch, a 45-minute drive from South Bend. They stretched a measuring tape across the water and began taking readings. One of the students, Shannon Speir, held a metal rod with a bulb on the end where the ankle-deep water met waist-high grass. The device registered the streamflow’s pressure against the bulb and transmitted this information to a digital display she had slung over one shoulder.

“Point-oh-two, grass,” Speir called up to the other grad student, Matt Trentman, who jotted down the number indicating how fast water was flowing through the grass at the edge of the channel. Then she moved the rod over an inch and took another measurement. After doing that all the way across the ditch and filling plastic tubes to test the water back at the lab, they moved a dozen yards upstream to a drain pipe conveying water from a nearby field for another set of measurements. Students working with Tank and her collaborator, Todd Royer, a scientist at the Indiana University, Bloomington, have been at this every two weeks for the last seven years. Add that to the expensive devices automatically measuring water quality every half hour, and the storm-chasing measurements Trentman makes when it starts to rain.

“Occasionally we do sampling every hour for 24 hours to see how things change throughout the day,” Trentman said, pencil in one hand, aluminum clipboard in the other. It’s a mountain of drudgery bringing microscopic focus to an unremarkable swath of land. This bit of Indiana is small in size, but large in the promise it represents: By braving sleet, pre-dawn hours, and the occasional rogue muskrat, a team of scientists has been able to show that it’s possible for farmers to keep their fertilizer from running off their land and causing problems downstream.

After 13 years and a million dollars in state, nonprofit, and federal funding, the data show a clear decline in nitrogen and phosphorus flowing out of this watershed during the critical springtime thaw. These two nutrients fertilize crops, but when they wash into the water, they fertilize algae blooms and cause a host of problems. In other words, the chemicals we rely on to grow food often end up poisoning the planet and threatening the lives of many species on it, including ours.

As far as I can tell — and I spent a lot of time looking — there’s only one place in the country where conservation measures have found a fix for this dilemma: the Shatto ditch.

The Shatto ditch drains 5 square miles of northern Indiana. It begins in low hills and travels 8 miles, with water seeping up from the ground and trickling down pipes protruding from the earth into the ditch. Then its water flows to the Tippecanoe River, and from there to the Wabash River, the Ohio River, and finally to the Mississippi River, carrying fertilizer washed off fields along the way.

Large amounts of nitrogen, one of the fertilizer nutrients that cause problems when washed off fields, are applied in the Corn Belt.

So much fertilizer flushes out of Corn-Belt ditches that it forms an oxygen-starved “dead zone” at the point where the Mississippi enters the Gulf of Mexico. Depending on the year, the size of this dead zone runs from 2,000 to 8,000 square miles, from the size of Delaware to that of New Jersey. Before reaching the ocean, fertilizers feed algae blooms that turn lakes into toxic slime; evaporate into the air in the form of asthma-triggering, climate-warming gases; and contaminate drinking water, causing blue baby syndrome, which prevents infants from absorbing oxygen. In 1997, the federal government formed a hypoxia task force in an effort to stem the flow of fertilizer pollution. Today, the government spends about $6 billion every year on the problem, but all that money has not made a detectable difference in the dead zone, the regular algae blooms in Lake Erie, and the health risks posed by fertilizer.

Even if you trace the mess upstream to small creeks and ponds, it’s hard to find any place that’s managed to clean itself up. Back in August, I’d set out to see if I could find a success story, one that might offer a template for others to follow. I started by contacting the Natural Resources Conservation Service, the federal agency formed after the Dust Bowl to help farmers take care of their land. The agency pointed me to Kutztown, Pennsylvania, where after 10 years of painstaking work, farmers and environmentalists had cleaned up the town’s drinking water enough to turn off a machine that had been removing fertilizer from the town well. I thought I’d found my story, until I learned that, after a couple rainy years, Kutztown had to turn the machine back on. Fertilizer pollution had returned to historic highs.

After several more dead ends, I finally found my way to the Shatto ditch, where a team run by Tank and Royer had documented lasting improvements in the area over the past seven years. Even during spring showers, they’d seen the sort of drop in pollution that would be needed to clean up the dead zone roughly 1,000 miles south — and that’s despite more rainfall, the main driver of nutrient runoff.

It’s clear there was a real change in this watershed. What was happening in Indiana? I made plans to go and see for myself.

It all started as a modest project by a collection of nonprofits, local agencies, and farmers to clean up the Tippecanoe River, one of the most important rivers in the United States for ecological diversity, and one of the last remaining healthy homes for the Midwest’s shellfish. It’s home to nearly 50 species of mussels, including threatened and endangered species with fantastic names: sheepnose, clubshell, fanshell, rabbitsfoot, and snuffbox.

In 2006, The Nature Conservancy proposed widening the Shatto ditch to keep these mussels from getting smothered under silt. The wider ditch would act more like a natural creek, with a floodplain that would allow high water to spread out and slow down during storms. The slower the water moves, the less sediment it carries.

But before bulldozers started digging into corn and soybean fields to widen the ditch, dozens of people and organizations had to get on board with the plan. Nothing would work without the cooperation of the people who owned the land and farmers who would have to give up around 15 feet of cropland on either side of the ditch for the expansion. And the best way to approach landowners was through the Kosciusko County Soil and Water Conservation District, a local agency run by a board of farmers and residents.

The project also couldn’t get anywhere without the county surveyor, Mike Kissinger, in charge of maintaining all the drainage ditches. The Natural Resources Conservation Service, or NRCS, helped secure federal grants, and scientists like Tank took on the duty of testing whether anything worked.

This coalition managed to widen the first half mile of the ditch in 2007. Then they doubled down, aiming to widen the rest of it and simultaneously convince the farmers whose land straddles the waterway to plant cover crops that might catch fertilizer before it left their fields.

A cover crop is simply something grown over the winter, when fields are usually bare. Rye grass, clover, and other plants hold fertilizer and soil with their roots, preventing it from washing downstream. Initially, 12 percent of fields draining into the Shatto ditch had cover crops, which the group managed to increase to 67 percent. Nationwide, just 4 percent of farmland grows cover crops.

Bob Foltz, who had been farming in the area for 65 of his 82 years, was already planting cover crops before the project began. But he was dead set against losing land to the second stage of the ditch. “I stated before they even dug this damn ditch that cover crops would be more efficient,” he told me.

The group proposed putting all of the floodplain on the far side of the ditch where it ran past Foltz’s field, which meant he’d lose a lot less land. Foltz begrudgingly allowed the bulldozers through his land, but remained dubious. “To me, it's just too damn much money,” he told me, never mind that the government would be paying the cost.

Kissinger made the case to farmers that widening the ditch would save them money in the long run. In theory, no one will ever have to scoop mud out of this ditch again. “It starts to silt up periodically and you have to go in and dip it back out every 5, 8, or 15 years,” Kissinger said. “In the long run, we think it’s going to be a tremendous savings.”

After backhoes finished moving mud to widen another 4 miles of the ditch in early 2018, the biggest flood in years hit the area. “I thought, ‘Oh my God, it's going to blow out,’” Tank, the Notre Dame professor, recalled. “But instead the floodwaters rose out onto those bare floodplains and slowed down, the particles settled, and we saw these streaks of sand forming.”

It’s basic hydrology. As water loses speed, it drops more of the dirt and sand it’s carrying, forming a rippled pattern on the streambed. Galloping, muddy floods become clear-running rills.

Even Foltz was impressed. He stopped in at the Soil and Water Conservation District office and said, “That thing really does work for flood control.”

The wider ditch and cover crops also succeeded in cleaning up the floodwater, which wasn’t entirely surprising. “We already know what works. I think we have identified the tools we're going to use to address the problem,” Royer said. The trick is in getting enough landowners to embrace them.

Shannon Speir fills a vial with water from the Shatto ditch for later analysis at the lab. Credit: Nathanael Johnson/Grist

As I talked to the people involved in the project, and then drove around northern Indiana to meet them in person, I organized the stories they told me about why it had worked into three categories: meetings, momentum, and money. No one emphasized meetings, per se: Instead they talked in vague terms about “the power of partnerships.” I confided to Jamie Scott, a farmer on the Kosciusko County Soil and Water Conservation District board, that all this fuzzy talk hinted at a fraught process. In my mind, partnerships meant meetings, and in my experience community meetings are dominated by the loudest, most self-serving voices.

A smile spread over Scott’s face as I spoke. “Everything you are describing is what happened in this watershed,” he responded.

There would be more obstacles in the way. One member of the group — with the clout to stop the project — had gotten the contract to excavate the first section of the ditch, and assumed that he’d do the rest of the work, but didn’t get the job. When NBC showed a video featuring the project during a Notre Dame football game, some people were upset that it didn’t mention their roles. People with strong personalities, like Mike Long, a farmer who had a different idea for the design of a portion of the new ditch, clashed with more soft-spoken sensibilities.

“There's times people would have liked to have taken him out back and dug a hole and buried him,” Scott said. “There's other times it wouldn't have got by without him.” Every time a conflict threatened to blow up the group, they managed to smooth things over.

I realized that bromides about partnerships were designed to avoid airing petty disputes. In the end, the ability to weather those disputes was the key to success. “Everybody could have gotten too frustrated and left, but they didn't,” Scott said. “You got to have the people to say: There's the goal. Forget about the clutter, forget about the squirrels, everything distracting us. That’s how this project got done.”

Those meetings only worked because many farmers had already embraced cover crops. The idea had momentum: The practice had been bubbling up through American agriculture long enough to have gathered steam. In an area where people aren’t always keen on “big government,” it helped that cover crops were not imposed by scientists, regulators, or environmentalists. The NRCS — long seen as a trustworthy advisor of farmers — had been zealously proselytizing the benefits of cover crops for years. The most innovative farmers had had ample time to experiment with cover crops, endure initial failures, and figure out what worked. Foltz and Long were already true believers who could tick off a list of benefits they were seeing: better soil, less erosion, better nutrient availability, fewer weeds and pests.

“It takes several years to get the soil opened up and the earthworms working,” Foltz said, “but now we think cover crops are giving us an extra 10 to 15 bushels of corn an acre, and that adds up real quick.”

Scott took me to one field planted with grasses as well as sunflowers, hemp, fat turnips, and thick-rooted radishes — some 20 species in all. He pushed a digging fork into the ground and leaned on it to expose a head-sized clot of soil. “There is just solid roots to that soil!” he said. “Look at all the earthworms. Look at those worm holes. If it rains 3 inches tonight, this soil isn't going anywhere. With a plowed field, if we get 3 inches that soil's movin’.”

All told, nearly 70 percent of the Shatto farmland — roughly equivalent to 600 football fields — was covered with ryegrass (and a few other cover crops) for six winters on end. The effects were dramatic. The water flowing out of the pipes that drained precipitation from the fields fell by about half, and the nitrates flowing out of those pipes fell between 80 and 50 percent, depending on the year.

“The cover crops are grabbing the nutrients,” Tank said. “They are not coming out when the water is flushed out.”

The project could have still fallen apart if it didn’t also come with piles of money. Contributions from The Nature Conservancy, the state, and the federal government covered the cost of the two-stage ditch digging and the university scientists making thousands of measurements. Federal dollars paid for a subsidy of $45 for every acre planted with cover crops. “Without incentives, it would have been a tough sell,” said Darci Zolman, a staffer at the county soil and water district.

This year, the $45 cover-crop subsidy ran out, and some of the farmers decided they’d plant them on fewer acres. This suggests that the money is crucial to replicating Shatto’s success and getting the lion’s share of farmers in the United States to use cover crops. But that wouldn’t necessarily mean taxpayers would have to fork over more money; farmers already get more than $11 billion in subsidies every year. The government could simply stipulate that farmers have to take conservation measures to receive federal money.

Long, the farmer with the big personality, said that the government has been giving farmers subsidies without asking them to take care of their downstream neighbors for too long. “Now I voted for Trump, don't get me wrong, but farmers have gotten kind of socialized under the Trump administration because he keeps giving us money,” he said. “For what? For doing nothing. I firmly feel that if there’s gonna be a government subsidy program it needs to be tied to environmental improvement. That's it. I'm against subsidies just to keep the poorer managers afloat.”

Jamie Scott, a farmer on the Kosciusko County Soil and Water Conservation District board, in a field covered by a diverse mix of cover crops. Credit: Nathanael Johnson/Grist

To start cleaning up the dead zone in the Gulf of Mexico, you’d need to bring a similar combination of meetings, momentum, and money to every watershed in the Mississippi River Basin — that is, expand what happened in northern Indiana more than 200,000-fold. When I asked people working on the Shatto ditch project how they’d recommend doing that, they quailed at the size of the challenge.

“We kind of laughed about the amount of work it’s taken over the last 14 years, just to get this off the ground,” said Chad Schotter, Kosciusko County district conservationist for the Natural Resource Conservation Service. To do the same thing for the entire Mississippi basin, he continued, “I don’t know. It’s going to take a lot of boots on the ground.”

The Shatto ditch is a triumph, but it may take more than incentives and neighborly persuasion to get 70 percent of fields in the Mississippi basin under cover crops and build floodplains for every drainage ditch. Meetings, momentum, and money alone probably won’t cut it.

Enforcing laws and regulations is the more direct route. Back in 1999, a major study of the Gulf of Mexico dead zone found that the cheapest way to staunch the flow of fertilizer would be to identify the worst culprits and switch those fields from widely-spaced row crops to something more densely planted like wheat. “If I were Tsar and had a Cossack army to back me up, I’d start with the marginal land and buy out the leakiest acres,” said Otto Doerring, the Purdue University economist who led that study. But without an armed cavalry, or even much political will in the Corn Belt, politicians have stuck to voluntary measures, rather than imposing unpopular top-down rules.

“Find a problem anywhere of this size that has been solved through individual action — there’s no precedent,” said Chris Jones, a research engineer at the University of Iowa who works on fertilizer pollution. When I first met Jones in 2014, he thought all the voluntary measures farmers were trying would make a dent in the problem. But as pollution only got worse in Iowa, he changed his mind.

If cover crops don’t become the norm, the problem is sure to get worse. The most severe nutrient leaching happens during drenching storms, and those are happening more frequently.

“If you have a couple significant storm events over the course of a year it can really mask the effect of all the conservation practices,” said Royer, the Indiana University scientist. “That's really concerning, because we are moving into a climate that's probably going to have more of those intense storms. The challenge is only going to grow.”

The beautiful idea behind voluntary conservation practices like cover crops is that they might align the self-interest of farmers with the national interest in cleaning up fertilizer pollution. Getting farmers to see it as a necessary part of keeping their businesses running “would be even better than a magic bullet,” Tank said. Demonstrate that these practices work for both the farmers and their downstream neighbors, and they’d spread on their own.

That’s already happening. Neighboring landowners who have seen Long’s success have asked him to farm their fields, and acquaintances approach him at church to ask for advice. As Scott was giving me a tour in his red pickup, there was a check made out to him for his cover-cropping services sitting on the armrest between us. He has a business helping farmers manage 100,000 acres of cover crops throughout the region.

There are market forces behind cover crops now. Crop-duster airplane pilots are making extra money dropping seed into corn and soy fields in autumn, so that cover crops can get a head start before harvest. Seed companies and consultants profit by helping cover crops spread.

And maybe the very act of adopting conservation practices will open the door to other policies. The farmers I talked to in Indiana were genuinely concerned with cleaning up their mess. Experimenting with cover crops can open your eyes to the role of a farm as part of a larger system, Scott said.

When I asked him to elaborate, he told me about a friend of his who farms land downstream, where two rivers meet. “He's sitting right there between between the White and the Wabash, and I mean, he floods all the time,” he said, shaking his head sadly. “His dad flooded maybe 1 out of 10 years, but now he's to the point where they're flooding 8 out of 10 years. And I told him one day, ‘Man, I'm sorry.’

“He's like, ‘There's nothing you can do about it.’

“I said, ‘There is something I can do about it. I feel like we are part of your problem.’”

It’s clear that leaving land bare and muddy, with hard soil from years of plowing, increases flooding during storms. Allowing fertilizer to escape in runoff hurts people downstream: the shrimpers in Louisiana, the lakeside residents and vacationers whose waterways turn slimy green. The state of Iowa alone sends tons of nitrogen fertilizer into the Mississippi River each year: Enough to fill 4,800 railroad tanker cars, about 13 per day on average, Jones calculated. The factories that make all that fertilizer emit tons of greenhouse gases, and the fertilizer-fueled algae blooms emit tons more.

Shut off this firehose of waste, and we’d be improving habitats, health, and the makeup of the atmosphere. It might also save farmers trainloads of money. No one is saying the kind of improvement seen in the Shatto ditch is easy, but maybe it’s worth the struggle.

This story is a collaboration between The World and the Center for Public Integrity — a nonprofit, nonpartisan newsroom that investigates betrayals of public trust — as well as Grist, a nonprofit media organization covering climate, justice, and sustainability for a national audience.

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