Water resources and water usage: have we hit peak water?

In the familiar debate over the future of oil exploration, peak oil means the point at which extraction of oil has reached its maximum. At that point, remaining deposits become increasingly inaccessible, and so extraction rates must decline. Life after peak oil is usually described as some kind of doom and gloom scenario. Now, it seems, the US hit peak water in 1970 and nobody noticed.

Take away the overheated rhetoric, and the concept of peaking is a useful tool in planning for the use of any finite resource. But how does it apply to the earth's water supply? Isn't that a renewable resource? Yes, but it can reach limits on how humans can use it.

A river would seem to be a renewable resource, constantly replenished by rain and snow melt. But so much water gets taken from the Colorado River that there hasn't been enough for any to reach the ocean for about half a century. Underground aquifers would also seem renewable, but several, including the Central Valley Aquifer in California, are being drained faster than nature can recharge them.

Is that more doom and gloom? Not if we reached it this country more than a generation ago and researchers are only now figuring it out. Water use statistics are fragmented and difficult to interpret, but researchers at the Pacific Institute have suggested that water usage and the GDP grew at about the same rate until about 1970. After that, water use declined somewhat and then stabilized even though both the GDP and the population have continued to increase.

It appears, therefore, that economic and population growth do not automatically require growth in the use of resources. It further appears that finding ways to use resources more efficiently can be relatively painless.

There is, of course, a big difference between oil and water. Oil is not renewable in any way. Eventually, we will have to stop using it--and the sooner the better. Multiple technologies exist to derive energy from other, renewable sources.

Before we can stop using oil, we have to find a stable and sustainable way of using what's left. It doesn't have to be painful. I, for one, find an excess of political rhetoric and lobbying much more troubling than any shortage of oil.