Manitobans don't realize how nutrient loading in Lake Winnipeg will hurt them economically and in their standing in the world, says the author of a book on Canadian freshwater lakes.
Quick and sustained action is needed, said Robert Sandford, author of Cold Matters: The State and Fate of Canada's Fresh Water.
If not, "Manitobans are doomed to live next to the world's largest open-air sewer," he told the Thinkers' Conference at University of Winnipeg on Saturday.
Lakes are harbingers of environmental conditions, and Lake Winnipeg is a prime example, Sandford said.
Global warming has increased evaporation of water bodies but that evaporation has to go somewhere: the atmosphere. Moisture content increases seven per cent for every one degree Celsius increase in temperature, according to the Clausius-Clapeyron equation.
That evaporation creates "atmospheric rivers" that dump huge one-off rain events on areas. That creates floods.
The impacts of increased flooding alone are staggering on economies. Manitoba's flood of 2011 cost $1.25 billion. Sandford demonstrated with a graph that flood events have increase exponentially in Manitoba the past two decades, unlike any period in the province's recorded history.
"With a flood one in every four years, you'll go broke eventually. Government won't be able to handle the flood losses," said Sandford.
In turn, floods in the Central Great Plains that includes Manitoba and North Dakota carry fertilizer and other nutrients into rivers and eventually into Lake Winnipeg.
Alga blooms have increased 300 to 500 per cent on Lake Winnipeg in the past century. Algae dies and consumes oxygen in the process that aquatic life like fish need to survive, said Sandford. The condition is called eutrophication.
"Extreme weather events become the norm and increase nutrient loading," he said.
It will take a mammoth cost and effort to revive a lake the size of Lake Winnipeg, Sandford said. One area to look at is to pay farmers to keep wetlands to hold back water, he said. Increased drainage on farmland has exasperated the nutrient loading problem.
Dead lakes can recover. That requires control of phosphorus as demonstrated on Lakes 226, 261, 303 and 304 in the Experimental Lakes Area, which is being terminated by the federal government.
But that was demonstrated on a relatively small scale compared to what will be required for Lake Winnipeg.
The three-day Thinkers' Conference wrapped up Saturday with speakers including Fiona Moola of the David Suzuki Foundation.