A Thirsty Industry

Oil sands mining operations in the Athabasca region depend on large quantities of water to extract bitumen from the sands. Using current technology, oil sands operations require between 2 and 4.5 barrels of water for every barrel of synthetic crude oil produced. Approved and operating oil sands projects are allowed to withdraw 349 million cubic metres of water per year — that's enough water to meet the needs of a city of two million people, a population twice the size of the city of Calgary. Planned oil sands projects will increase water withdrawals by more than 50% to 529 million m³ per year.

Oil sands operators withdraw most of the water used in mining processes from the Athabasca River and its tributaries. They are currently responsible for about 65% of total water withdrawals from the Athabasca River, making them the greatest — and fastest growing — users of the Athabasca in the province. While the government regulates water use, the current rules for oil sands water withdrawals use targets instead of limits, and are voluntary instead of compulsory.

Contamination and Containment

90% of water withdrawn from the Athabasca River by oil sands operations cannot be returned to the river. Pollutants from bitumen contaminate the water during the oil extraction process, resulting in a toxic mix that cannot be released into the ecosystem. Instead, contaminated water is recycled to the extent possible, and then contained in massive tailings ponds to allow contaminants to settle over an indefinite period — effectively removing the water from the Athabasca River Basin.

Smartening Up on Water Use

The ecological sustainability of the Athabasca River is of paramount importance, and industry has both the financial capability and intrinsic capacity for technological innovation to deal with periods when water withdrawals may need to be limited or stopped to protect the Athabasca River.

One viable option is to avoid water withdrawals during periods of low flow. Most companies are already building water storage into their projects, and a 2004 study demonstrated the viability of storing additional water in off-stream reservoirs to avoid damming the Athabasca River. This practice is routinely used in southern Alberta to supply water for irrigation during low flow periods. New technologies are also being developed that may reduce the volume of water required in the extraction process. However, the government is approving projects and development is proceeding before tighter regulations and more efficient technologies can be implemented.

Additional Impacts of Mining

Oil sands mining can have additional impacts on aquatic ecosystems, wetlands and aquifers.

Surface mining operations disrupt the landscape by removing vegetation and other land cover (overburden), affecting drainage over a wide area. This can destroy wetlands and eliminate peatlands, which take centuries to develop. These impacts have long-term effects on local ecosystems, and there is little possibility that the ecosystem functions of disrupted areas will be restored.

Deep Oil Sands Operations and Ground Water Impacts

Oil sands development also has a profound impact on groundwater resources. More than 80% of the oil sands reserves are too deep to be mined using conventional practices. These resources can only be accessed through in-situ extraction, which uses water-intensive drilling processes. Long-term, it is likely that water demand from deep oil sands extraction will be as great or greater than for oil sands mining. This problem is intensified by the fact that deep oil sands development — which has been growing faster than anticipated — most often uses fresh groundwater.

Conventional oil sands mining operations also have a substantial impact on groundwater as aquifers must be "depressurized" to prevent flooding of the mine pit. In some cases, mining operations require the complete removal of wetlands, which recharge groundwater when functioning as part of a healthy ecosystem.

At the present time, we do not fully understand the cumulative impacts that water withdrawals, depressurization and voidage will have on shallow groundwater. Moreover, we have insufficient monitoring to provide adequate baseline data and record changes. Deep saline aquifers are expected to supply about 40% of the water required for in situ operations over the next 20 years, but use of saline water also creates impacts, associated with the disposal of waste from water treatment processes.