In an oil sands mining operation the amount of water that has to be brought in from the river depends on how much oil sand is mined, how much water is used in the process (which can vary depending on the ore quality and the process used), how much water is recovered from the tailings, and how much water from other sources such as snow or rain is collected (most runoff water and seepage water from the mine site is collected and transferred to the tailings ponds for use in the extraction process). For typical conditions, about 3 to 4.5 m3 of new water must be brought on site for every m3 of bitumen that is produced.
Example: It is difficult to determine what fraction of the Athabasca River water is used because water flow in the river varies tremendously from season to season. For example, if bitumen is being produced from surface mines at about 750,000 barrels a day (2008 estimate of production from surface mines) about 2,625,000 barrels of new water would be needed per day. If all new water needed was taken from the Athabasca River, that amount would equal about 2.6% of the Athabasca River during the winter (on average), or 0.6% from spring to fall (based on average river flow recorded up to 2002). These values would be 5% withdrawn during the winter and 1% during summer if the calculation was based on the lowest flow in the river that has been recorded up to the year 2002.