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Scientists install and program a surface-water sampler on Spencer Creek, just downstream from the Valens Reservoir near Cambridge, Ont.Peter Power/The Globe and Mail

The Beverly Swamp does not look like a system in drought. The spongy ground, rich and moist and black, is littered with fallen leaves damp with fall drizzle as the Spencer Creek trickles quietly by.

But below the surface, this marsh outside of Cambridge, Ont., is deeply parched in yet another of the extreme weather events hitting this region with increasing regularity.

That will all change at 6:30 a.m. Tuesday, when researchers from the University of Waterloo literally open the floodgates to reset our understanding of climate change.

Instead of basing ecosystem research on baseline data and historical information – the environment as it has been – this research team is manufacturing a flood to create the extreme future we're now entering.

It's part of a massive field-lab experiment that has trickle-down implications for the Great Lakes and, beyond that, the global ecosystem.

For ecohydrologist and lead researcher Philippe Van Cappellen, the "flood pulse" is the culmination of eight months' work, and a chance to test some sneaking suspicions about the flow of pollutants through a besieged ecosystem.

"My gut feeling is that we'll see less nitrogen and more phosphorus and silicon," said Dr. Van Cappellen, who is the Canada Excellence in Research Chair in Ecohydrology.

"Instead of pollutants being released at the same rate as water flows past, extreme events could actually unlock more pollutants than standard flows would indicate. We could have this hidden flow of nitrogen and phosphorus right beneath our noses."

The water being unleashed from the Valens Dam Tuesday morning will flow through the Beverly Swamp – the largest remaining marsh in southern Ontario – into Spencer Creek and on toward Hamilton harbour and Lake Ontario.

The buildup of nutrients in the Great Lakes (a process called eutrophication) is overstimulating algae plants, causing algal blooms so large they can be seen from space.

The blooms clog up the lake and rob the water of oxygen, creating "dead zones" in which fish and other organisms cannot survive.

Lake Erie's algal blooms were so bad this year that they've been cited as a possible cause of death for tens of thousands of fish that washed up along a 40-kilometre stretch of lake shore on Labour Day weekend.

And this past spring, the

cross-border International Joint Commission that oversees the Great Lakes listed Lake Erie's eutrophication as one of its top three priorities for the coming three years.

Zoom even farther out to the global scale, and our understanding of how nanomaterials and micronutrients behave in the environment is poor. We know even less about how these elements react in extreme events.

"There's still a lot we don't really understand about the response of the Great Lakes to these changes. We still don't completely understand the system," Dr. Van Cappellen said.

For its part, the Conservation Authority is keen to get its hands on the data gleaned from the next three days of round-the-clock monitoring, followed by weeks and months of data collection.

HCA water resources engineering manager Hazel Breton said the local climate has already changed dramatically.

"Where the region used to get snow in winter, it is now more likely to get rain. Spring runoff has decreased significantly, replaced by "incredible summer thunderstorms dropping a whole lot of water at the one time," she said .

"This summer was as extreme as you can get. In one day, we reported floods in some waterways and droughts in others. … We didn't simulate that drought. Nature simulated it for us."

As the water begins its surge from the Valens Dam, and researchers wearing bright orange vests to deter hunters traipse through the swamp on specially built walkways, Dr. Van Cappellen will be flying back from Ottawa where on Monday he addressed the Senate kiosk on water science.

While he'll miss the crucial first hours of the flood pulse experiment, he will spend the coming weeks and months combing through the data in a bid to find out exactly what is going on around us – and what is likely to come.

"It's very urgent," he said. "Nature teaches us there is a lot of resilience in ecosystems. If we can steer those processes, we could do what I call ecological engineering.

"The important thing is to anticipate the problem. Once a problem is full-blown, [the ecosystem] is much less likely to go back."

Editor's note: An earlier version of this article incorrectly identified the lake that Hamilton harbour flows into. This online version has been corrected.

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