By Alexandre Touchette
In an ironic twist, the completion of a $6.5 million project aimed at solving a drought problem north of Montreal has been indefinitely postponed by heavy rains. The cofferdams built at the mouth of the Mille Iles River in August were no match for the rushing waters that flooded the worksite.
Officials are deepening the Mille Iles River near Montreal because of drought.
It is hard to imagine that less than two weeks ago this section of the river was still buzzing with heavy machinery. Back-hoes were pounding the dry river bed with jack hammers while trucks were being filled with big chunks of rock.
Crews are shaving 20 inches of rock from a 15,000 square meter area of the river’s bottom to increase the flow from the Deux Montagnes Lake to the Mille Iles River. When the water levels are too low, this high spot acts like a dam and most of the water from the lake follows the path of least resistance into a deeper river to the south.
Quebec took these drastic measures to deal with the lowest water level ever recorded in a river that supplies 440,000 suburbanites across 11 communities on the north shore of Montreal before emptying into the St. Lawrence River.
In August, the flow in the Mille Iles dropped to 15 cubic yards per second, a mere trickle compared to the 118 cubic yards per second average for that month. To work properly, the region’s water treatment plants need the river to flow at least 46 cubic yards per second.
So something had to be done.
“When the water level in the river is reduced, the contaminants are not as diluted, so more chemicals and longer processing time are needed to purify the water,” says Phillippe Kouadio, a water treatment specialist. The water quality in the river rapidly declines in low water events. Nine sewage treatment plants send effluent directly into the Mille Iles River; five others discharge into its tributaries.
Climate change, growth expected to tax Great Lakes water
The extremely low levels seen this year in the St. Lawrence River and its watershed are linked to last winter’s unusually low snowfall. The spring runoff was insufficient to raise water levels. Lower than average rainfall made things worse.
Such conditions could become more frequent across the Great Lakes region as scientists predict less snow and more irregular rain due to global warming. Richard Turcotte, chief hydrologist for Quebec’s provincial government, acknowledges that some models anticipate the river flow in dry periods to be cut by half by 2100.
There is no debate that the province’s $6.5 million emergency solution secures sufficient water levels.
But the question is for how long.
“We can’t start to scrape every river bed in Quebec, says biologist Edith Lacroix, spokesperson for the Eau Secours coalition, a group that promotes sustainable water use in Quebec. “Nature has its limits and we have to start adapting ourselves to the situation.”
Guy Garand, executive director of the Laval Regional Environmental Council, a local environment group, believes that municipal leaders are reaping what they sowed.
“In order to grow their tax base, they want unrestrained growth,” he says. “They tolerate all kind of shoreline encroachment that inhibit the natural mechanisms that help retain water. Wetlands and flood plains where ground water can be recharged are destroyed at an appalling pace.”
About 80 percent of the wetlands near Montreal have been destroyed.
Streams in Laval are still transformed into concrete canals to ensure fast drainage of storm water in new subdivisions. Instead of being filtered by plants and wetlands along the shore, and slowly released to the river, the water now rapidly flushes through the system.
Comprehensive regional water policy needed
Biologist Edith Lacroix says that it is time to implement real water saving programs. Subsidies to encourage high efficiency toilets and shower heads are part of the solution, she says. But more aggressive measures are needed.
“We need to prioritize; agriculture is essential but pools are not,” says Lacroix.
Per capita water consumption in Canada is second only to the U.S. and nine times greater than the UK’s average.
Over the past 10 years, both the water pumped from the Mille Ile River and the sewage dumped into it has risen. From 1986 to 2005 the population of the area that drains to the river grew by 62 percent on average and as much as 175 percent in some subdivisions.
Garand believes that even if blasting the riverbed is unavoidable, it is not a cure but a sign that a comprehensive water policy is badly needed.
In a province that boasts 4,500 rivers and 3 percent of the world’s freshwater, it can be easy to forget that water is a scarce resource.