The drought that panicked the seven Colorado River States from the late 1990s through the mid 2000s is not an uncommon occurrence in geologic time, the National Research Council reported this week.

To us in Walla Walla, it seems irrelevant that Colo., Wyo., Utah, Ariz., Calif., Nev., and N. M. may have to struggle for their share of the Colorado River. But this report is meaningful not only for its environmental consequences, but because the Klamath and Columbia rivers are next in line if Las Vegas gets thirstier.

Now, it’s fair to point out that Phoenix has a five month supply of homes on the market, and that the housing boom in the West will likely slow down. But in the last several decades the number of people migrating to the Sunbelt has been significant and constant; it’s a nice place to live.

The problem is that food manufacturing – corn, peas, and the like have large and growing water budgets. They also have run into limited water rights. The same is true for housing developments and irrigated agriculture. There isn’t much more water: the Colorado basin has been divvied up since 1922, when the Compact between the seven western states apportioned 16.4 million acre-feet annually between them.

The problem is that in fact only about 12-14 million acre-feet flow on average annually down the Colorado River, and with the increase in development the demands are getting higher. In the first decades after the Compact, the answer to the aridity in the desert was: “build more dams.” In the last few decades, it’s been “get more efficient.”

The measures taken to increase efficiency, such as piping ditches and leveling fields, have been effective at reducing the need for irrigation water per acre, but have meant that any recharge, which would have gone into the ground and the aquifers to support wild plants and animals, has been seriously reduced. So, as the engineers and water policy experts have slowly tried to steer the West towards more efficient use of water, they have systematically squeezed the last remnants of the springs that fed the small stream and ponds that kept the Wild West wild.

Now it appears that there is even less water available than was previously thought. The likely end result is that the water will eventually all be turned from the agricultural uses that it was initially intended for and start moving towards the metropolitan areas where deep pockets and a lower per capita usage mean significant sums of money for farmers willing to sell or lease their water rights.

These cross-basin water transfers often involve large aqueducts moving the water in a sealed pipeline for hundreds of miles. There isn’t much chance of developing a spring without a rupture in the pipeline.

The Mexican farmers on the other side of the All-American Canal are already facing the problems associated with efficiency. For decades they have been using the excess water from the cotton fields in Yuma, and the water that flows from the Colorado down to the San Diego. Since the United States has begun to cement the Canal, the water has been drying up. The Mexicans have sued to get the water back, claiming that they have been using it for years and that it is rightfully theirs.

If the National Research Council is right, then this sort of water dispute over the benefits of efficiency might well become the norm. It also looks like, as the population of the Sun Belt increases, the demand for water from the big Northwest rivers will also increase. If it turns out that there isn’t sufficient water in the Colorado River, there will be no shortage of people trying to buy the irrigation water out of the Columbia or the Snake.

If Washington wants to see its water stay here to protect the wildlife here, we might want to look carefully at making sure that we know where the water can go, and where it can’t. It looks like another Compact may be in order.