Around 1,5 million cu. Metres of mud were washed away from the Ha! Ha! river and accumulated in the "Eaux-Mortes" sector.
Once the Ha! Ha! Lake was completely emptied, tree stumps that had been submerged till then were discovered.
Located on the sides Ha! Ha! River, the small villages of Ferland-Boilleau were seriously hit by the floods of July 1996. A long section of Route 381, linking the La Baie district to the Ferland-Boilleau sector, was swept away, isolating its citizens from the rest of the Saguenay-Lac-Saint-Jean area for many days. Many people were airlifted to safety thanks to Bagotville's 3rd Military Squadron. To re-establish road links, a section of Route 381 was built in record time, three weeks, on the west bank of the Ha! Ha! River.
The most abundant precipitation fell upstream from the Ha! Ha! barrier lake, on the Ha! Ha! River watershed. This is the area were one can find the villages of Ferland-Boilleau.
The core of the dyke on the Ha! Ha! barrier lake was made up of clay. The huge water swell, which engulfed the villages of Ferland-Boilleau before hitting the La Baie district and flowing into the Saguenay River, found its origins in the fact that the fragile clay core was completely leached out by the gushing waters.
30 million cu. Meters of water were the main cause of the rupture of the dyke on the Ha! Ha! barrier lake. Once the dyke was destroyed, the water dug a 20 metre deep trench across the forest before engulfing the village of boilleau and reaching the Ha! Ha! River. The rushing waters had an impressive speed of 32 km per hour.
At two o'clock in the morning on July 20th 1996, the Ha! Ha! barrier lake waters went over the Cut-Away dyke. That's when 26 million cu. Metres of water were added to the torrential rain and then streamed into the Ha! Ha! River.
The Cut-Away dyke was completely destroyed in a few hours.
Before the floods of July 1996, the Ha! Ha! lake was filled with water and was a busy vacation resort. In the water swell, the Cut-Away dyke, located upstream on the lake, couldn't withstand it. When it gave way, the lake was emptied and 26 million cu. Metres of water surged into the Ha! Ha! River, destroying everything in its passage before reaching the Ha! Ha! Bay. The rate of flow was 100 times greater than usual.
Photo : Jean Vallée
Here is what the Ha! Ha! Lake and River looked like after the Cut-Away dyke disappeared.
When the Cut-Away dyke gave way, the Ha! Ha! Lake poured its waters in the Ferland-Boilleau sector, forming a new riverbed before reaching the Ha! Ha! River.
Some of Ferland-Boilleau's homes were damaged to such extent that they ultimately had to be burned. For the people concerned, it was devastating, psychosocial support was necessary to help the population.