CHATHAM-KENT — The water-filtration system near the edge of Louis Roesch’s Chatham-area soybean farm doesn’t look like much — just a couple of concrete pads and a few plastic barrels.
But below ground, important work is being done, as the system absorbs phosphorus from agricultural runoff. “We’re trying to capture phosphorus [at the edge of the field] before it enters the waterways,” explains Colin Little, agricultural program coordinator for the Lower Thames Valley Conservation Authority, on a muggy morning in late July.
The system, which cost about $12,000 and serves 25 acres, is part of a larger effort by the Thames River Phosphorus Reduction Collaborative — established in 2015 and made up of the Great Lakes and St. Lawrence Cities Initiative, the Ontario Federation of Agriculture, and various local groups, including the conservation authority — to test phosphorus-reduction methods that focus on the areas between the edge of the farm fields and Lake Erie.
The collaborative is planning to test a number of such methods, which could end up being adopted by farms on both sides of the border, says Randy Hope, mayor of Chatham-Kent and co-chair of the collaborative.
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Ever since 2012, when Canada and the United States signed an agreement pledging to take action on high phosphorus levels in Lake Erie, the two countries have been working to make a dent. Canada’s public and private sectors have shelled out at least $30 million on research and pilot projects aimed at identifying the sources of the phosphorus leaking into the lake and at developing ways to eliminate them — and the toxic algae blooms they produce.
In 2016, the two countries committed to reducing the amount of phosphorus in the lake’s western and central basins by 40 per cent by 2025 (using 2008 levels as a baseline). Ontario has established an interim target of a 20 per cent reduction by 2020. The U.S. has the next seven years, then, to reduce its annual phosphorus loads by 3,316 tonnes. As Canada is responsible for far less phosphorus runoff, its target is far lower, at 212 tonnes.
But this binational effort to save Lake Erie is progressing much more slowly than a previous rescue attempt, mounted after phosphorus levels ballooned in the 1960s and ’70s. Then, a $7.5 billion cleanup effort took only a decade to produce results. Today, scientists are expressing doubts that Canada and the U.S. will be able to meet their targets.
“I’m not saying yes or no; I’m saying I don’t think that the science is there to say definitely that we can,” says Nandita Basu, an engineering and environmental-sciences professor at the University of Waterloo whose research helps predict how long it will take water-quality-improvement measures to take effect.
Part of the issue is that the lake’s current algae problem is more complicated than the one it faced last century, says Andrea Kirkwood, an environmental microbiologist who serves as an adviser to the Great Lakes International Joint Commission, which assists Canada and the U.S. in finding solutions to problems in internationally shared waters. The sources of phosphorus and phosphates were easy to identify: detergents and inadequate sewage treatment. “Cause and effect was very obvious,” she says. After phosphates were restricted and sewage-treatment processes improved, the blooms disappeared.
The phosphorus entering Lake Erie today, though, comes primarily from commercial fertilizer and manure. And agricultural runoff isn’t as easy to control as wastewater from urban areas.
A February report from the International Joint Commission estimates that 40,000 tonnes of phosphorus-laden fertilizer leak into the lake’s western basin annually. Around 72 per cent of that comes from U.S. farms, and the remaining 28 per cent comes from the Canadian side. Scientists have traced Canada’s phosphorus loss to land around the Thames River watershed and tributaries that run through Leamington in Essex County.
The agriculture industry is voluntarily working on several different fronts to reduce nutrient losses. Responding to a campaign to reduce fertilizer use that is being led by the Ontario government and industry groups such as Fertilizer Canada, many farmers are adopting new technologies, such as computerized systems and mapping that allow them to sync the amount of fertilizer they apply with local field conditions. They’re also changing farming practices — burying fertilizer beside seeds when planting, for example, rather than leaving it on top of the ground, where it might be washed away — and the fields themselves, adding wind breaks and buffers, retiring land, and restoring wetlands.
Federal-provincial funding and cost-share programs — such as a $4.1 million commitment made by the federal government earlier this year in its Lake Erie action plan — are helping support such initiatives. The programs are administered by organizations such as the Ontario Soil and Crop Improvement Association and ALUS (alternative land-use services) Canada, and industry groups are also chipping in by helping fund research and pilot projects.
Still other farmers are allowing researchers to study their land to determine whether field-management techniques and infrastructure, such as belowground drainage systems, are contributing factors.
But even a small leakage can be enough to cause blooms, and scientists are increasingly concerned about the effects of phosphorus that accumulated years ago in fields, streams, reservoirs, and the lake. “Even if we stopped phosphorus from coming off of the landscape, we’ll still have to deal with this legacy phosphorus that’s in the system,” Kirkwood explains.
Changes in the ecosystem have created new obstacles: the warming weather associated with climate change helps promote and sustain algae blooms. And the invasive zebra and quagga mussels that have taken up residence in the lake help shift nutrients closer to the shore, contributing to the formation of blooms.
Plus, conflicting information and new discoveries can present challenges. Merrin Macrae — a professor of geography and environmental management at the University of Waterloo who researches phosphorus loss on Ontario farms — says that studies about farm practices have produced differing results.
Recent studies suggest that a variety of factors affect phosphorus loss in Ontario — the type of soil involved, for example (UW research published in July indicates that different soils have different capacities for holding on to phosphorus).
Findings related to the role played by no-till have proved particularly contentious. The much-lauded conservation technique avoids plowing, which causes erosion in farm fields, leading to phosphorus loss. But some studies show that when used in areas that, like Essex Country, are home to heavy clay-based soils, the technique may actually contribute to phosphorous loss in heavy rains. Further complicating matters, recent studies conducted by Macrae and her students suggest that the technique doesn’t cause a loss when used on other types of soils in Ontario.
Finally, testing solutions takes time. In labs, it’s easy to create specific conditions, says Little. But, he adds, “I can’t tell Mother Nature to dump two inches of rain on me tomorrow.”
Basu says her students are working on computer modelling for the Thames River watershed to provide more realistic phosphorus-reduction timelines for the area. She hopes the project will be completed within a year. “We’ll see,” she says. “I think science could and science should start providing these numbers relatively soon.”
She notes that some cleanup projects in the U.S. have faced criticism after overrunning their timeline estimates — and she worries that delays in the Lake Erie cleanup effort could create a similar response. Her advice is not to be overly concerned if we don’t seem to be making much headway in reaching our targets — and not to allow a missed milestone to discourage cleanup efforts. It’s important to act now, she stresses. “Things really are getting worse.”
This is one in a series of stories about issues affecting southwestern Ontario. It's brought to you with the assistance of faculty and students from Western University’s Faculty of Information and Media Studies.
Ontario Hubs are made possible by the Barry and Laurie Green Family Charitable Trust & Goldie Feldman.
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