A new model for reducing water pollution

- Winnipeg, Manitoba

Charting the way to cleaner water

One of Canada’s most vulnerable waterways is the Red-Assiniboine Basin where storms and spring flooding send a great number of agricultural pollutants into Lake Winnipeg, the area’s largest fresh-water resource. The resulting nutrient runoff acts like fertilizer, feeding microscopic algae which multiply rapidly and which create an “algal bloom” that depletes the oxygen in the water, increases water toxicity and puts fish, wildlife and people at risk of consuming these toxins.

Because the Red-Assiniboine Basin straddles the Canada-U.S. border, it falls under the mandate of the International Joint Commission (IJC), a binational organization charged with overseeing shared water use by both federal governments. Knowing that pinpointing the origins of these pollutants is key to reducing their impact on the lake's ecosystem, the IJC sought an organization that could help it to track the source of the nutrients and to identify the most problematic “hot spots”.

In 2011, the IJC commissioned the National Research Council's (NRC) Marine Infrastructure, Energy and Water Resources (MIEWR) program to lead a watershed-scale study that would help both countries to identify where they could most effectively focus their efforts towards nutrient abatement and control.

A two-way flow

According to Glenn Benoy, Senior Water Quality and Ecosystem Adviser for IJC’s Canadian Section, most traditional models to assess water quality are designed for small-scale usage. They also do not provide federal, provincial or state water resource managers with a holistic view of the source of these nutrients across the Red-Assiniboine Basin. Says Benoy, “We needed a robust, large-scale model that could provide meaningful tracking data for recommendations to governments of both countries.”

To create this desired model, NRC experts applied a new approach to an old technology. Originally developed by the U.S. Geological Survey (USGS) in 1997, the Spatially-Referenced Regressions On Watershed (SPARROW) modelling tool has long been used around the world to estimate the origin and destination of contaminants in small-scale river networks. To effectively identify Lake Winnipeg’s hot spots, NRC modified the SPARROW tool and used it to carry out the first-ever trans-border water quality analysis of this scale.

Modifying SPARROW in this novel way – which had never been attempted before – allowed dozens of disparate geospatial and water-quality datasets to be integrated into a single tool that could process data from both countries. This provided jurisdictions on both sides of the border with access to the same information on their shared waterways.

Turning the tide towards the future

While researchers on the project included experts from NRC, Environment Canada, IJC and the USGS, the modifications made by NRC are unique in the unprecedented amounts of detail that can be accommodated and interpreted. “NRC has done an astonishing job of taking dozens of complex features of the landscape and turning them into seamlessly linked layers of geographic information system data on either side of the border,” says Benoy.

The model, which provides both numerical data and visual capabilities, has since helped the binational team successfully identify and map many problematic nutrient sources, among them crop fields, livestock farms and wastewater treatment facilities.

Now that the Red-Assiniboine Basin study is complete and the modified SPARROW tool has provided a deeper understanding of the sources of pollution in Lake Winnipeg, the IJC has asked NRC to leverage the new technology to analyze pollution sources in all five Great Lakes. Just one way that this unique solution will spill into other waterways across North America and beyond.

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