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magazine / ma97

March/April 1997 issue

by Canadian Geographic and L’actualité

After the deluge
Water powered the Saguenay region’s economy, then almost destroyed it
By Taras Grescoe

SOUTH OF THE concrete dam that marks the beginning of Rivière Ha! Ha!’s journey towards Quebec’s Saguenay Fiord, the boreal forest gives way to a broad swath of mud and boulders. On the morning of July 20, 1996, the rainwater that had been collecting in Lac Ha! Ha! for 28 hours flowed over an all-but-forgotten retaining wall of earth and tree trunks. Instead of emptying through the gates of the dam owned by the pulp and paper company Stone-Consolidated, 30 million cubic metres of water ruptured the earthen dike, digging a 20-metre-deep trench through the forest before joining Rivière Ha! Ha! and swamping the hamlet of Boilleau with churning mud and uprooted trees. As 200 residents watched from the safety of a newly formed island — the church — seven houses were detached from their foundations and sent whirling away. A placid stream, never wider than a three-lane roadway, had become a wall of water moving at up to 32 kilometres an hour, collapsing cliffsides and tearing out bridge pilings. Farther downstream, it hit the city of La Baie with the force of a bomb. One hundred and forty-eight houses and cottages — as well as the vault of the Caisse populaire — were washed far out into the brackish waters of the Saguenay.



The catastrophe: the Saguenay floods were the most devastating in Canadian history, resulting in: 10 deaths; $800 million in damages; 1,718 houses and 900 cottages destroyed or damaged

The deluge: the two-day rainfall was equivalent to the volume of water that tumbles over Niagara Falls in four weeks

Fleeing the floods: 16,000 evacuated; 40,000 meals served over four weeks at CFB Bagotville; $4.26 million in temporary lodging assitance to 1,703 claimants

Unchecked harnessing: most of the region’s 2,000 dams and dikes were built before the 1960s, with minimal environmental and technological controls. Plans to build a dam on Lac Ha! Ha! received government approval in 1962, 12 years after it was built.

Purged waterway: floodwaters deposited 25 to 50 centimetres of sediment in Baie des Ha! Ha! — 75 to 150 years’ worth. It was enough to bury the mercury and other chemical pollutants that had accumulated on the bottom of the bay since the 1950s.

Throughout Quebec’s Saguenay-Lac-Saint-Jean region, other rivers, swollen by the kind of rain that normally falls on the Himalayas, were cascading over dams, chewing through embankments, and washing over sub-divisions. By July 21, the rains had destroyed 488 homes and damaged 1,230, and forced the evacuation of 16,000 residents. Miraculously, the rivers themselves killed no one: the 10 people who perished that weekend were crushed in their cars and houses by landslides or killed when their cars fell into huge crevices in roadways. Premier Lucien Bouchard, visiting the ruined towns of his home region after the catastrophe, called the floods an "act of God," and a "once-in-10,000-year" event.

Viewed from a temporary bridge near Boilleau on a September day, the new course of Rivière Ha! Ha! makes a mockery of such pious absolutions. The remains of Lac Ha! Ha! — once frequented by moose, beavers and kayakers — is now a vast plain of mud. Downriver to the north, there are hundreds of millions of dollars worth of damage, and families wondering whether they will be living in friends’ basements all winter. In between lies a burst dike — and a story of how the harnessing of the Saguenay’s rivers turned a natural phenomenon into a man-made catastrophe.

ON THURSDAY, JULY 18, a huge cyclonic depression — the kind meteorologists call a comma because of its distinctive shape — started forming over the centre of North America. Moving counter-clockwise, it spiralled from west of Hudson Bay, over Manitoba and the American Midwest, leaving the continental mainland just over Virginia. North of Cuba, these patchy clouds fused into water-laden giants. Four miniature hurricanes, set in motion by evaporation from the ocean’s surface over the Gulf Stream, pumped water into the sky. By the time the depression curved back toward Nova Scotia, it had become a vast rain machine, a direct conduit between the waters of the Caribbean and the Canadian mainland.

The head of this 4,000-kilometre-long comma swept to a halt over the Saguenay-Lac-Saint-Jean region, northwest of the St. Lawrence River. Nestled in a slight depression in the Canadian Shield, the 155-kilometre-long Rivière Saguenay is a changeling, at once a fiord of the St. Lawrence — whose salty tides mount to Chicoutimi — and a freshwater river fed from the northwest by Lac Saint-Jean. The major communities of the region — Alma, Jonquière, Chicoutimi and La Baie — are strung along the southern bank of the fluvial stretch of the Saguenay, among a narrow swath of low-lying fields stitched together by snaking ravines. To the south, the rounded peaks of the immense Réserve faunique des Laurentides climb to 1,143 metres before dropping toward Quebec City; on the northern horizon, the plateaus of the Valin massif rise to close to a kilometre. The Saguenay valley is in fact a graben — a depression created when a tectonic block subsides — between two parallel faults: one running along the Rivière Sainte-Marguerite to the north, the other to the south near Lac Kénogami. The valley is a temperate oasis, a patch of the Quebec landscape where the forest briefly makes way for pastures and wheat fields.

Forty-five major watercourses feed into the Saguenay and Lac Saint-Jean. The region’s hydrological network is a crazy quilt, pieced together over the first six decades of this century and made up of 2,000 structures — mostly dikes and embankments — owned by 25 public and private organizations. The larger dams are brutally efficient exploiters of the topography. As rainwater and snowmelt drop through the dams’ turbines, their voyage from the heights of the Canadian Shield to the St. Lawrence is transformed into millions of kilowatts of electricity for the region’s industries. Alcan needs a 24-hour-a-day supply to extract aluminum from bauxite ore; Abitibi-Price and Stone-Consolidated use it to boil and grind the forest into pulp; and Hydro-Québec sells it directly to the people of the province. The provincial environment ministry’s dams on Lac Kénogami control the flow of water to smaller hydro-electric dams downstream.

AT 1 A.M. ON JULY 19, the first drops of what would become a torrential downpour began to fall on the region. Over the next 50 hours, 155 millimetres — an amount normal for the entire month of July — fell on soils already saturated during the previous two weeks. Due to the orographic effect of the Laurentian peaks — in which mountains force the air to rise and cool, provoking condensation — the drainage basin of Lac Kénogami received almost twice as much rain as the lowlands between Jonquière and La Baie. Satellite images taken at the height of the storm show a gigantic clot of clouds, almost perfectly stationary, over the headwaters of the Chicoutimi and aux Sables rivers. An automatic gauge in the Réserve faunique des Laurentides recorded a total of 279 millimetres of rain, most of which fell in a 36-hour period. It was the equivalent of 10 buckets of water emptied over every square metre of soil.


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