||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.
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.
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.
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.
Can Geo POLL
The Earth’s climate is changing, and it’s causing problems for those of us who live here. From drought to rising seas to melting ice caps, which effect are you most worried about?