How water is used
We use water in many ways, and assign different values to those uses. Instream uses (e.g., for transportation and recreation) are valued highly, but it has proven difficult to give them a dollar value that has any real meaning. For example, just what would the average consumer be willing to pay to swim in a clean lake or for a chance to catch fish in a clean, unpolluted river?
By far the greater number and variety of water uses occur on land. These are called withdrawal uses and, although important to our daily lives, they have tended to be assigned a low value. Water is withdrawn, used and then discharged. Most withdrawal uses “consume” some of the water, which means less is returned to the source than was taken out. And, after it has been used, the quality of the water that is returned is often diminished, which has a negative impact on both the environment and recreational instream uses.
In 1996, five main withdrawal uses accounted for a total annual water intake (extractive uses) of 44.6 billion m3. These uses are described more fully in Freshwater Series A-4, “Water Works!” and are briefly described in this figure:
- Thermal power generation includes both conventional and nuclear power generating plants, which withdrew about 64 percent of the total water intake in 1996.
- Manufacturing accounted for 14 percent of water withdrawals in 1996. Paper and allied products, primary metals, and chemicals were the main industrial users.
- Agriculture accounted for nearly 9% of total withdrawals, with the semi-arid Prairie region of Canada accounting for 75% of this total. Agriculture consumes a large portion of what it uses, returning less than 30% to its source where it can be used again. Irrigation is the largest agricultural consumer of water.
- Municipal use accounted for 10% of all water withdrawals in 1996, or 12% when similar rural uses were included (excludes industrial uses and large-scale agriculture). In the municipal sector, more than half of the water demand is a result of residential use.
- Mining use, including metal mining, non-metal mining, and the extraction of coal, accounted for 1 percent of all water withdrawals in 1996. Water is used by the mining industry to separate ore from rock, to cool drills, to wash the ore during production, and to carry away unwanted material.