Unprecedented flooding wreaks devastation, death and destruction - How does the Ottawa River dam system work?

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Added: Wed, 05/08/2019 - 7:05pm
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The rising Coulonge River left the bottom of the Marchand Bridge in Mansfield submerged.

Allyson Beauregard

MRC PONTIAC & PONTIAC – Over a thousand Pontiac residents have been forced from their homes as the Ottawa and Coulonge rivers reached their highest levels in recorded history; 109.09 (in the Coulonge area) and 887 meters above sea level, respectively. The Ottawa River’s second highest level (in the Coulonge area) was reached in May 1979 (108.85 m), slightly higher than May 2017 (108.52 m). The second highest for the Coulonge River was in April 2002 when the water reached 829 m. 
The army visited several municipalities to secure municipal infrastructure and help with sandbagging, and many roads were closed. To add to the devastation, one woman lost her life in the Municipality of Pontiac after she drove into a major washout on Bronson-Bryant Road in Quyon late in the evening of April 19.
Although water levels have currently stabilized and are receding in some areas, according to Michael Sarich, senior water resources engineer with the Ottawa River Regulation Planning Board (ORRP), a second peak, which potentially could reach the high levels of the first peak but not exceed them, is expected before mid-May. Water levels are expected to remain high for the coming weeks because of the slow release of northern reservoirs. The disastrous levels in 2017 were experienced during the second peak in May. Residents are advised to keep sandbags in place.
Are the dam operators responsible?
The ORRP was established by the Canadian, Québec, and Ontario governments in 1983 in order to “ensure integrated management of the principal reservoirs of the Ottawa River Basin and it’s tributaries”, to provide protection against flooding, and maintain the interests of users, notably hydro producers. 
In flood situations, the first instinct is sometimes to blame dam operators for not holding back water. Sarich briefly explained how the Ottawa River dam system works, noting there is currently a daily exchange of information between the ORRP and the dam operations, including Brookfield on the Black River,  Hydro Québec and Ontario Power. Water level meters are located throughout the basin, and based on these results and forecasted inflows, the parties determine a operational strategy. Dam operation is based on balancing the risk of flooding in both upstream and downstream areas.
Thirteen principal reservoirs were included in the 1983 integrated management agreement, seven of which affect the Ottawa River levels between Rolphton and Fort-Coulonge. During the winter, they are emptied to make room for as much northern spring runoff as possible to mitigate flooding. The six northernmost reservoirs (from Lac Temiskaming and further north) have significant storage capacity to hold back water.
The Des Joachims facility, which includes the seventh reservoir, can create a far-reaching backwater flooding effect, so it is maintained at half capacity in the spring to limit both upstream and downstream flooding. Once the probability of upstream flooding is reduced, the rest of the reservoir is filled and the dam returns to normal operating levels.
The rest of the dams have minimal capacity so they are unable to influence the flow of water down the river. They generally adjust their gates to allow the same amount of water to pass through as what arrives.
Additional gates are opened to accommodate high received volume, which was the case in Portage-du-Fort when the gates closest to the village were opened for a period of time.
Due to the natural characteristics of the river, some dams, like the one in Bryson, lower their levels and maintain them as close as possible to original river conditions (before the dam was built) because they create huge back-flooding effects. Holding back water can pose serious risks to the facilities and upstream communities.
Northern reservoirs are rapidly filling and the average summer level has almost been reached on Lac Temiskaming. According to Sarich, water is just starting to be released from the reservoirs and will take time to reach the Pontiac area.
Municipal situations
The following is the situation in the municipalities affected by the flooding. All ask that residents refrain from travelling on flooded roads unnecessarily.
Alleyn-et-Cawood – About five residences were moderately flooded by the Kazabazua River.
Bristol – About 30 residents voluntarily evacuated, a state of emergency was declared, four roads were closed, and about 60,000
sandbags were distributed. The historic church in Norway Bay was a concern, but was protected with sandbags. 
Bryson – A state of emergency was declared and three residents voluntarily evacuated. A berm was constructed along Havelock Street to protect residences. About five houses were affected.                       
Campbell’s Bay – Twenty-five people were evacuated from River Road, which was closed as well as a section of Second Street. Local schools were closed to limit strain on the waste water system.
Chichester – Twelve residences were affected and four people evacuated. Two roads remain partially closed.
Clarendon – Twelve cottages were affected, and many residences conducted preventative sandbagging. Over 6,000 sandbags were distributed. Laughren Road remains closed, but is expected to be fixed soon. 
Ile-du-Grand-Calumet – A state of emergency was declared, berms were made along chemin des Outaouais, and 25 residents evacuated.
L’Isle-aux-Allumettes – State of emergency was declared and the two local schools and daycare closed for the week of April 29. Over 50 permanent residences and 130 cottages were touched by the waters and several others were at risk. At least fourteen area roads were closed where either mandatory or voluntary evacuations took place. A temporary shelter was established at the St. Joseph’s Family & Seniors Centre. A water and sewer usage restriction was in effect in the village of Chapeau. 
Litchfield – Flooding was severe on McGuire Road and both Pilon and Crawford roads are  partially closed. The bridge near the intersection of Giroux and Crawford roads was closed due to damage.
Municipality of Pontiac – Over two dozen roads were closed, and a state of emergency declared. Nearly 300 residences were affected and 500 people (10% of the population) evacuated, including a large part of Quyon because of concerns about a large dyke constructed on Ferry Road, which was stabilized using multiple loads of gravel. Some Quyon residents were allowed to return to their homes on May 5. A makeshift road was created to reach the Community Centre and sandbag it. Both Quyon schools and the CLSC were closed. More than 170,000 sandbags were distributed compared to 45,000 in 2017. Residents are asked to limit wastewater discharges.
Mansfield/ Fort-Coulonge – A state of emergency was declared in both  municipalities, an emergency disaster centre was created at ESSC high school, and local schools were closed the week of April 29. The white bridge was under surveillance because of the water level and debris had to be cleared from it. Residents are asked to limit the strain on water and sewer systems. In Fort-Coulonge, nearly 100 homes and over 200 residents were evacuated. In Mansfield, 365 residences and three businesses were flooded, and 200 people evacuated. Twenty roads were closed and the Patro on Chemin
de la Passe suffered extensive damage.
Portage-du-Fort – Some residences were flooded, but there were no major problems.
Sheenboro – One resident was evacuated and portions of some roads remain closed, but according to Mayor Doris Ranger, the flooding is minor to moderate.
Waltham – A state of emergency was declared and over 30 buildings and residents were evacuated. Two roads remain partially closed and the Black River Road
completely closed.
Compensation?
Premier François Legault, announced that provincial flooding compensation will now be capped at a cumulative total of $100,000. The government will also offer homeowners up to $200,000 to relocate.
The Red Cross will be donating $600 to some of Québec’s hardest hit families who have registered at www.redcross.ca.
In a press conference in the Municipality of Pontiac on April 30, Mathieu Lacombe, Minister responsible for the Outaouais region, said the government will be looking into providing extra money to municipalities to repair damaged infrastructure in the coming months, but that it’s “too early to talk about money.” 
Pontiac MP Will Amos emphasized that although federal disaster relief funds
are available, the provincial government determines the modalities. Many residents are skeptical about its distribution given that some homeowners still haven’t received compensation from the 2017 disaster.