Troubled Waters: One year later, more trouble ahead

BRANDON, Minn. — A three-hour drive separates the rolling hills of Minnesota’s Douglas County from the front steps of the Bell Museum of Natural History. But a year after the controversy over Troubled Waters—the Bell’s film on farmland pollution in the Mississippi River basin—brought words like “dead zone,” hypoxia” and “nitrogen fertilizer” to the attention of the general public, what’s happening in places like west-central Minnesota provides an insight into what the future holds for the health of the entire watershed all the way to the Gulf of Mexico.

“Douglas County is at the headwaters of the Chippewa,” says local Soil and Water Conservation District staffer Jerry Haggenmiller. “So the water here flows all down hill.”

Haggenmiller is saying this while leading a recent summer tour of innovative conservation measures being used on farmland in the region. Several miles south of here the Chippewa flows into the Minnesota River, which then meanders across the state before dumping its load into the Mississippi at Fort Snelling. One of the stops on the tour is a hilly cornfield near Brandon, where a handful of cattail-growing patches—each about the size of a two-car garage—are located in low spots. Buried beneath each spot of rank vegetation is an innovative drainage system that uses pea gravel to filter eroded sediment out of the water before it begins its long journey to the Gulf, a couple thousand miles away.

Later in the day, Haggenmiller and other conservation experts show off numerous other innovations for keeping sediment, nitrogen fertilizer and other contaminants out of the Chippewa, and eventually the Minnesota and Mississippi. Besides alternative drainage systems, on display are sediment basins, grassy waterways, rotational grazing systems and shoreline restoration.

 “We’ve seen a lot of good examples of taking care of the land,” says Jennifer Hoffman of the Chippewa River Watershed Project at the end of the tour. “These are good conservation measures that go above and beyond.”

But a drive around the Chippewa watershed, followed by a trip to the Twin Cities, makes one thing clear: more corn than ever is being grown in Minnesota, mostly at the cost of pasture, hay and other perennial plant systems that can hold soil and contaminants in place.

Indeed, a few days after the Douglas County conservation tour, the USDA announced that Minnesota farmers planted over 8.10 million acres of corn this year, a five percent increase from 2010 and the second largest planting behind 2007’s 8.40 million acres. Some 90 percent of that corn received applications of nitrogen fertilizer at an average rate of 125 pounds per acre. That’s an important statistic, since nitrogen fertilizer making its way to the Gulf of Mexico is a leading cause of the hypoxic “dead zone” there.

A few weeks after the USDA crops report was released, scientists in the Gulf reported that this summer the dead zone covered an area larger than the state of Connecticut. At 6,765 square miles, this year’s dead zone is larger than the five-year average of 6,688 square miles.

In a sense, 2011 has been a microcosm of the struggle to clean up the Mississippi River. A few steps forward—use of innovative farm conservation measures. A few steps back—more acres than ever covered in nitrogen-hungry corn. A few steps forward—point pollution sources such as factories and municipal sewage systems are being identified and controlled. A few steps back—nonpoint sources such as farmland runoff are far outstripping point sources as a problem.

The backward steps are threatening to outpace the forward ones, according to a study published in the Proceedings of the National Academy of Sciences. As corn acreage climbs to record levels in response to demand for ethanol (after sinking to as low as $2 a bushel a few years ago, corn could sell for as much as $8 later this fall), the overall amount of nitrogen fertilizer present in the watershed is bound to go up, according to the Proceedings study. Scientists have estimated that nitrogen levels in the Mississippi River basin will need to decrease by 30 percent to 50 percent to shrink the dead zone. But the increase in corn cultivation required to produce 15 billion gallons of ethanol by 2022 would increase the amount of nitrogen in the Gulf by at least 10 percent, concludes the Proceedings study.

And an increasing amount of that nitrogen is coming from Minnesota and Wisconsin, says a U.S. Geological Survey study released in August. In fact, nitrogen flowing into the Mississippi from those two states has increased 76 percent since 1980, a major factor in why nitrogen levels in the Gulf have jumped 10 percent during the same period.

The good news is farmers have reduced their use of nitrogen dramatically over the years, thanks to more precise cropping techniques and higher prices for the nutrient, among other things. In 2005 the average Minnesota farmer was using as much as 139 pounds of nitrogen per acre, at least 10 pounds more than they use today. But even in years when nitrogen fertilizer use has leveled off or dropped, the hypoxic zone keeps growing. Why? Part of the reason is that Midwestern fields are so saturated with nitrogen, and so much more water is running off them thanks to artificial drainage, that it could take several years to see positive effects down in the Gulf, says Dennis Kenney, former director of the Leopold Center for Sustainable Agriculture. Studies have shown that high levels of nitrogen can show up in tile lines even if it’s been years since fertilizer was added to the land they drain.

But there’s no doubt that replacing annual row crops like corn with perennials like pasture and hay could help reduce nitrogen contamination significantly. For one thing, such perennial systems aren’t reliant on nitrogen fertilizer to thrive. For another, they reduce water runoff significantly, which keeps rivers downstream cleaner. In a six-year study of southwest Minnesota tile drainage systems, recently retired U of M soil scientist Gyles Randall found that nitrate-nitrogen losses from continuous corn and corn-soybean systems were about 37 times and 35 times higher, respectively, than from land planted to perennial hay crops or in perennial grass systems. The study period took place when precipitation levels ranged from 36 percent below normal to 66 percent above normal.

And it’s those above normal precipitation levels that are becoming a bigger part of the problem. Since 1970, there has been a marked increase in heavy rainstorm events in the U.S., especially in the Midwest, Great Lakes regions and the Southwest, says the Bulletin of the American Meteorological Society. That means conservation methods and structures such as conservation tillage and terracing may not be able to handle these intense, infrequent storm events.

 “We have conservation measures that were built for a climate scenario we no longer have,” says Jerry Hatfield, director of the USDA’s Laboratory for Agriculture and the Environment.

But perhaps one of the biggest steps backward in the struggle to clean up the Mississippi is the inability of farm groups and environmentalists to even agree on the basic science surrounding the issue. In a letter earlier this month announcing his resignation as the MPCA’s Mississippi River Basin coordinator, Norman Senjem made it clear there remains a huge gap between farmers and natural resource professionals on the issue of cleaning up the basin. The result, he wrote, is that not much actual cleaning up of water has been accomplished in recent years.

“…we are faced with the same dreary zero-sum-game as ever, pitting the environment against agriculture,” wrote Senjem. “If we believe that, we are unlikely to find common ground.”

But Senjem hasn’t completely given up—he’s seen what can happen when farmers and local conservationists work together on the watershed level in areas like the Chippewa basin, out of the limelight of national or statewide mandates to “clean up the river.” That’s why, when he leaves the MPCA on Sept. 27, he will go to work for the Zumbro Watershed Partnership.



Brian DeVore