Water – How we share it

What do we mean when we talk about watersheds, river basins, catchment basins, and drainage basins?

Generally speaking, these four terms have similar meaning and are frequently used interchangeably. They refer simply to the total land area drained by a river and its tributaries. Originally, "watershed" denoted the imaginary line, or drainage divide, separating the waters flowing into different rivers or river basins, and is still often used in this context. Through common usage, it has also evolved to mean the area drained by a river system. "Drainage area" and "watershed" are more prevalent in North American practice, while "catchment" is customary in British and Australian water source communities. Canada's landmass is composed of five major drainage basins: Atlantic (which includes the Great Lakes and the St. Lawrence River); Pacific; Hudson Bay; Arctic; and the Gulf of Mexico. Each of these can be further divided into a hierarchy of progressively smaller basins or watersheds down to areas that drain individual lakes and rivers.

Do most river basins fall within provincial, territorial, or national boundaries?

River basins are defined by topography. Smaller basins (sub-basins of the larger basins) often fall within provincial or territorial boundaries. However, most larger basins cross one or more of these boundaries. For example, the Mackenzie River basin contains seven provincial and territorial boundaries, as well as federal lands, and involves three provinces, two territories, and the federal government in its management. Some basins, such as the Saint John River basin, extend beyond the Canadian border. These are often referred to as Canada-United States "boundary waters". The Great Lakes are an example of a very large boundary basin.

Mackenzie River basin: 
Saint John River basin: 
Great Lakes-St. Lawrence River basin: 

Do we divert water between different watersheds and river basins in Canada, and if so why?

In Canada, major diversion projects have been developed by power utilities to increase flows for hydroelectric production, especially in northern projects such as the Churchill-Nelson region in Manitoba and in the James Bay region in Quebec. Projects have also been constructed for irrigation purposes and industrial development such as aluminum production.

While, in the past, major diversions and transfers have been used to fulfill water resource and economic development objectives, it is widely recognized that we have moved away from the era of large scale diversions and transfers in Canada and the United States. Environmental and social considerations are making these transfers of water a less desirable option. Present approaches now favor reducing the demand on water uses.

What are the advantages and disadvantages of diverting streamflow from one drainage basin to another?

In the past, diverting flow from one basin to another has been primarily based on economic development through energy generation, irrigation, and industrial output.

Interbasin diversions can have undesirable social and environmental consequences. For example, the amount of water being removed in relation to the amount of water available, existing water demand and uses, quality of water being transferred, including the potential for the introduction of undesirable non-native species and pathogens, can all have significant impacts. The implication of introducing non-native species is particularly significant when major drainage basins are involved.

Social structures may also be affected. Sometimes communities are flooded out or people are forced to change their livelihood or otherwise modify their traditional way of life. For example, the Aboriginal community of Southern Indian Lake in Manitoba had to be partially relocated as water levels rose behind a control structure so that the reservoir could spill through a diversion channel into the Nelson River. The community was also forced to abandon its commercial fishing on the lake, as mercury from flooded soils accumulated to dangerous levels in the whitefish.

In order to protect the health and integrity of Canada's drainage basins the Government of Canada opposes bulk water removals, including interbasin diversions, from major Canadian watersheds. However, decisions on smaller scale diversions must be weighed carefully between the economic benefits to society and the environmental disruption of water-based ecosystems and the impact on communities within the watersheds.

How do problems arise over sharing water?

We all live downstream from somebody else! If water is removed, consumed, or transferred upstream, it will not be available downstream. If the river flow is reduced, even temporarily, by upstream storage such as a reservoir, then downstream activities such as shipping, recreational boating, and fish spawning may suffer. Similarly, pollution upstream can make the water unfit for use downstream and force downstream users to clean it up before it can be used again.

Is it complicated to work out a solution to user conflicts?

User conflicts arise because the same water is required for many purposes. A lake, for example, provides the water source for a community's drinking water while at the same time providing for the needs of farmers, boaters, swimmers, and local industry. The biggest challenge, when conflicts arise, is obtaining the support of all parties to study the problems and to work together to find a solution. Rarely is a single government or agency responsible for all of the actions required to prevent or resolve any given conflict among users. The issues are often complex and complicated and involve a number of different types of studies (technical, economic, environmental, sociological, and legal).

Public involvement at various stages during the process is vital. Above all, what is needed is a real commitment from all parties to maintain an open dialogue focused on maximizing social, economic, and environmental benefits.

Are there any rules governing how two or more provinces, territories, or Aboriginal governments share the use of water from the same river or lake?

There really are not hard and fast rules unless the governments involved have negotiated such rules among themselves. For example, after many years of negotiation, the three Prairie provinces agreed in 1969 on a formula for sharing common water sources. The agreement ensures that one half of the natural (eastward) flow of waters originating in or flowing through Alberta is reserved for Saskatchewan, and that one half of the eastward flow originating in or flowing through Saskatchewan is reserved for Manitoba. In addition, a broad water resources cooperation agreement was concluded in 1997 by governments in the large Mackenzie River basin. The agreement endorsed the principle of managing water resources for future generations in a manner consistent with the maintenance of the integrity of the aquatic ecosystem and provided for early and effective consultation on potential developments in the basin.

What arrangements do Canada and the United States have for the sharing of boundary waters?

The longest-standing and arguably one of the most important bilateral environmental agreements between Canada and the United States is the Boundary Waters Treaty  of 1909. The treaty established the principles and mechanisms to prevent and resolve disputes regarding the quantity and quality of these waters. These principles provide the basis for the protection of waters shared by our two countries. Pursuant to the treaty, governments established the International Joint Commission (IJC)  in 1911 as an impartial binational commission to oversee the implementation of the treaty. The treaty stipulates that the IJC's approval must be obtained for situations involving the use, obstruction, or diversion of boundary and transboundary waters that affect the water's natural level or flow. The treaty also allows for the governments of Canada and the United States to use the IJC as an independent fact-finding mechanism to carry out studies on matters of concern along the boundary and to make recommendations to both governments. As a result of the IJC's work, additional institutional arrangements have been established for the management of specific boundary waters. For example, IJC studies and recommendations on Great Lakes pollution led to the establishment of the Great Lakes Water Quality Agreement in 1972 and its subsequent amendments in 1978 and 1987. In addition to a number of international agreements on shared boundary waters, more than 20 water boards have been established to oversee the management of various boundary and transboundary watersheds and report either to the IJC or to the Canadian and U.S. federal governments.

Some neighboring provinces and states have also entered into voluntary arrangements for managing and protecting boundary water resources. The best known example of this type of arrangement is the Great Lakes Charter of 1985, signed by the eight governors and two premiers of the Great Lakes-St. Lawrence River states and provinces. The charter commits the signatories to manage the water resources of the Great Lakes basin cooperatively and in accordance with a watershed strategy that reflects the unity of the Great Lakes system. In the Atlantic region, the province of New Brunswick and the state of Maine have set up the International St. Croix Waterway Commission to deal with the water management issues of this shared river basin.

Why is the Chicago diversion from Lake Michigan of interest to Canada?

The Chicago diversion is the largest and best known out-of-basin diversion of the Great Lakes. The diversion was built in 1848 as a means of alleviating water quality concerns in Lake Michigan and to provide a navigation link between the Great Lakes and the Mississippi River. While the rate of the diversion has at times exceeded 280 cubic metres per second (m³/s), the United States Supreme Court decreed in 1967 (amended in 1980) that the rate of diversion of water from Lake Michigan into the Illinois-Mississippi system be limited to 91 cubic metres per second. Periodically, pressures develop within the United States to increase the rate of diversion, but these are opposed by Canada and by most of the Great Lakes states because of the negative impact on downstream hydropower generation, navigation and shipping, and other economic aspects throughout the Great Lakes-St. Lawrence drainage basin.

Canada, as well as most of the Great Lakes states, oppose any increase of the diversion. This binational opposition coupled with the existing United States Supreme Court Decree suggests that further proposals to increase the flow of the diversion are unlikely at this time. 

A lot has been written about bulk water removals, including water exports. Does Canada export any water now?

Canada does not export water in bulk via interbasin-transfers, pipelines, or by ocean tanker. Water is exported in small consumer containers and it is also shared between some border communities for domestic water supply purposes. Bulk water removals can individually and cumulatively cause undesirable environmental impacts.

Early in 1999, the Government of Canada launched a comprehensive strategy to prohibit the bulk removal of water from the Canadian portion of major drainage basins, including water removal for export purposes. The strategy is based on principles of ecosystem integrity and sound watershed management. Actions by both the federal and provincial/territorial governments are required to fulfill the strategy.

The strategy includes amendments to the International Boundary Waters Treaty Act to prohibit the bulk removal of water from boundary watersheds, principally the Great Lakes; a joint reference, with the United States, to the International Joint Commission to study the effects of water consumption, diversion, and removal, including removals for export from boundary waters; and a proposal to develop, in cooperation with provinces and territories, a Canada-wide accord for the prohibition of bulk water removals to protect all of Canada's watersheds.

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