(click for a larger image)
|The chart shows some preliminary data from the Okanagan basin supply and demand model. It focuses on the water extracted from the basin for human consumption (rather than the much larger amount that evaporates naturally--which, of course, we can do nothing about). The full presentation from the Okanagan Basin Water Board can be found here.
It is important to note that some of these consumptive use categories are more "consumptive" than others. For example, much of the water used for "indoor domestic" eventually makes it back into the basin, either through sewage treatment or through infiltration from septic systems into ground water. As such, the 7% allocated to domestic indoor use overstates the net water impact of residential indoor use (low flush toilets don't save water; they save pumping). Much the same can be said about institutional, commercial, and industrial consumption. Outdoor uses, such as agriculture, golf courses, and domestic outdoor (lawns and ornamental gardens) result in evaporation and thus represent a true loss of water from the Okanagan basin (the water that evaporates from our lawns apparently falls as rain in the Kootenays).
Here a distinction is increasingly made between "working" and "non-working" water. Say what you will about golf courses, but at least they yield a substantial economic benefit for their 5% water use. Then there is non-working water, which really only applies to the 24% wedge labeled "domestic outdoor". I have always believed it is every Canadian's God-given right to have as much lawn and cedar hedging as he or she wants. We might be forced to reconsider this is the Okanagan if we want to maintain the other wedges of the pie. Interesting resource in this regard: The Okanagan Xeriscape Association.