The following is the text of a public information brochure published by the Ottawa River Regulation Planning Board in 1984:
Flow Regulation – Ottawa River
It might be expected that the 30 storage reservoirs – with more than 14 billion cubic metres capacity – in the Ottawa River basin would suffice to contain the floodwaters that occur each year in the Ottawa River system. In many years they do, and especially during so-called dry years. But sometimes in spring a heavy snowpack a late thaw, above normal rains, or a combination of these abnormalities can cause damaging floods.
Following recommendations of the Committee on Flow Regulation, Montreal Region, a study was initiated in 1977 by agencies of the governments of Canada, Quebec and Ontario. Some findings of this study, together with recent actions to cope with the problem, are discussed in this brochure.
Use of Basin Water
In early years, the Ottawa River was used mainly for navigational purposes. It was the route of explorers and fur traders' to the interior of the continent and a part of the inland route between Montreal and Kingston. Later, it carried great rafts of logs to mills for processing.
The first reservoirs on the river were built to aid navigation. augment low flows during dry years and provide some flood control. Later, more reservoirs were established with hydroelectric energy production their primary purpose.
With the rapid urbanization in the 20th century and changes in needs of the basin's population, there has been a change in the use of the river. Today's greatest needs are for hydroelectric energy generation, domestic water supply and effluent dilution (wastewater), recreational boating and, to a limited extent, log driving. Environmental protection has also become a major cause for concern.
Fortunately, many uses of the waters are compatible. Storage of waters in reservoirs operated primarily for the benefit of power generation, can reduce flood flows, similarly, release of these waters during drought periods augments flows. Within the area of integrated management of the resource, there is hope for further reduction of flood damage.
Characteristics of the Basin
From its source east of the Dozois Reservoir to its confluence with the St Lawrence River, the Ottawa River has a length of more than 1,130 kilometres. For most of its length, it forms the boundary between the provinces of Ontario and Quebec. Its basin has a total area of 146,300 square kilometres, 65 per cent of which is in Quebec and 35 per cent in Ontario.
Principal Reservoirs in the Ottawa River Basin
(having more than 200 million cubic metres live storage)
|Rapid VII (2)||371|
|des Joachims (5)||229|
|Montreal||Lady Evelyn (6)||308|
|Madawaska||Bark Lake (8)||374|
|Poisson Blanc (13)||625|
*Capacity is measured in millions of cubic metres.
The Ottawa River Basin
Hydroelectric Energy Production
There are 43 hydroelectric generating stations in the Ottawa River basin with a combined capacity of some 3,500 megawatts. On average, these developments generate electricity with a value of about $1 million per day, and are important to the economies of both Quebec and Ontario. The current climate for energy conservation accentuates the importance of hydroelectric energy production. For this reason, the study had as its objective not just to reduce flooding, but to do so without adverse effect on the production of energy.
The Flood Problem
Because of the basin's size, shape and topography, highly varied meteorological conditions result in equally varied responses in water levels from tributaries. Different times of response of the main tributaries combine to produce two distinct flood peaks, about three weeks apart.
The first flood peak in the Ottawa River originates from unregulated flows from its southern tributaries. The second peak results from a combination of high flows from the tributaries of the north shore together with flows from headwater areas, and is partially regulated. While the first peak is generally the lesser of the two, it can cause considerable flood damage since ice is still in the river and ice jams can occur.
A continuous monitoring of hydrometeorological conditions in the basin helps to predict the occurrence of floods and droughts, but the current state of meteorological scientific and technical knowledge still leaves a substantial degree of uncertainty.
Costs associated with flooding are not only monetary but also have a human element as families are uprooted from their homes and transported to temporary quarters until floodwaters that have enveloped their homes subside.
Search for a Solution
Flooding along the Ottawa River, its tributaries and in areas near its confluence with the St. Lawrence River are not a recent phenomenon. So why hasn't the problem been solved already?
Factors involved in the prolongation of this problem are mainly the types of floods, location of areas damaged, causes of damages, nature of the hydrologic events, limited capacity of existing reservoirs, prohibitive cost of appropriate corrective measures, and the division of responsibility between three jurisdictions of government and between different levels within the jurisdictions.
Numerous studies have been undertaken on the construction and operation of dams and control facilities within the basin. Most of these works, however, have been built for specific purposes with little concern for the situation as a whole. Although several federal, Ontario and Quebec agencies were involved, a concerted effort to compile and consolidate the hydrological and meteorological records of the various agencies did not occur until the late 1940's.
Although government actions to modify operational procedures have been limited, reservoir owners have, in fact, been adapting their day-to-day operations to accommodate new flood constraints. The construction of the many dams and their operation has resulted in better, though still imperfect, flow control. This, and the infrequency of major floods, has encouraged movement of factories and dwellings onto the river's floodplain. This creeping invasion has obviously been part of the problem and has set the scene for serious damage during years of extreme flows.
Effect of Reservoir Operations
There are no simple solutions to the flood problems of the Ottawa River basin. For example, the southern portion of the basin is unregulated and reservoir storage has a limited effect on the first flood peak, which occurs about mid-April. The second peak, about three weeks later, is strongly influenced by reservoir operations.
Normal operations at the principal reservoirs can ensure that a significant portion of the spring runoff is stored. This should substantially reduce the magnitude of the second peak.
Since reservoirs provide the greatest flood control protection in the Ottawa River basin, one might assume that existing reservoirs in the middle or upper reaches could be enlarged or new reservoirs constructed to provide additional protection; but costs would be high in comparison to benefits. On the lower tributaries, which influence the first flood peak, few sites are available that could provide any benefit and, for these, costs would be prohibitive.
One action that has grown out of the study is the establishment of a permanent Ottawa River Regulation Planning Board, composed of three members from the federal government and two members each from Ontario and Quebec. It is the board's responsibility to establish and implement general principles, priorities and overall regulation policies for principal reservoirs in the basin.
A regulating committee is responsible for ongoing operations of principal reservoirs in the basin, within the policies, guidelines and criteria established by the board.
A secretariat has been established in the Ottawa-Hull area as an "executive arm" of the board, and to provide a coordinating centre for all matters pertaining to management of the basin.
In brief, the range of activities of the new board and its agencies is to obtain technical information and forecast the weather and runoff conditions throughout the basin so as to minimize the adverse impact of high/low flows and levels on the riparians' properties, and to maximize the benefits. To this end. long-term and short-term strategies for operating the facilities located on the river system will be formulated.
During an approaching flood, strategies will be assessed and revised as necessary each day to minimize the flooding in the whole basin. An inflow forecasting model simulates the behaviour of the whole Ottawa River system under the expected spring meteorological and runoff conditions. As a guide to the decision-making process, an optimization model has been made operational to permit integration of reservoir operations and to aim for reduction in peak flows. It assists the operators in the release of flows from each control facility to maintain flood control while having the least effect on the various other uses in the basin. Results from this model will also be used to keep the public informed on flows and levels, and their expected variations.
Studies show that in most years, integrated operation of the principal reservoirs can significantly reduce flood flows in the Ottawa River. But no economic solution has yet been found that will eliminate all flood damages during extreme years. Nevertheless, the board is confident that the measures under way, both technical and administrative, will provide relief from the flood damages of recent years and that with time, further alternatives will be implemented which will not only reduce flooding, but also maintain energy production and improve low flow augmentation and water quality in the Ottawa River basin.
For more information or a copy of this brochure, contact us by e-mail