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So why have the blooms returned? To meet the people who solved that mystery, I drove to Heidelberg University, in Tiffin, Ohio, whose 125-acre campus in the state’s corn belt houses what some scientists call a national treasure: a meticulous, 45-year record of the chemicals that flow into Lake Erie from two large tributaries, the Maumee and Sandusky Rivers. The collectors and proud curators of that trove are two women who have devoted more than 40 years to the task of diagnosing Lake Erie’s ills.
“We predate the EPA,” said Ellen Ewing, over lunch at one of the university’s dining halls. “We’re older than Earth Day!”
Ewing, who has short gray hair and the crisp, assured manner of someone who knows her work inside and out, was talking about Heidelberg’s National Center for Water Quality Research, founded in 1969. She has worked there since 1976, right after graduating from the university. Ewing started two years before her longtime colleague and fellow Heidelberg alum, Barbara Merryfield, sitting next to her at our table. Their job titles are lab manager and research associate, respectively—neither has a Ph.D.—but the data they’ve amassed over the decades have enabled researchers to understand the puzzling resurgence of Lake Erie’s algal blooms.
Every week for more than 40 years, Ewing, Merryfield, and their small team have collected water samples from the Maumee, Sandusky, and other watersheds. “I used to drive 500 miles a week,” Merryfield said. “I was out three days a week. Quite a few involved being stuck in the mud up to our axles.” With her strong build and denim shirt, she still looked capable of dealing with a mired four-by-four.
“When Barb had a work anniversary, I calculated the number of samples she had processed,” said Laura Johnson, an environmental scientist who has directed the center since 2016 and whose own work has been pivotal in unraveling the algal bloom conundrum. “It was way over two million, and I know that’s an underestimate.”
Every year they collect roughly 10,000 samples, testing each for 11 different parameters, Ewing noted, between bites of a salad. “We’re wickedly efficient.”
All that sampling revealed that a conservation practice that was supposed to improve the lake’s water quality has had the opposite effect. In the 1990s many farmers in the lake’s watershed incorporated “no-till” agriculture. Instead of plowing fertilizer into their fields every spring, farmers started to spread pellets onto the fields’ surface. The reduction in plowing did reduce soil erosion, but it unexpectedly has increased the amount of algae food flowing into the lake. When phosphorus was plowed eight inches or so into the ground, it remained tightly bound to the soil. But with phosphorus pellets sitting in the upper inch or two of the soil, the phosphorus dissolves and washes into the lake whenever the soil becomes saturated with rainwater. Researchers now use spring rainfall data to forecast the severity of algal blooms.
The number of days with two inches of precipitation or more has more than doubled in the past two decades, Johnson said: “That’s the big problem.” But, she added, it’s a problem we can fix. Johnson’s mentor, Jennifer Tank, an ecologist at the University of Notre Dame, has been working with farmers on ways to reduce runoff from their fields—and to prepare them for the rigors of a new climate era.
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