Depending on whom you talk to the Colorado River serves either 35 million or 40 million people, all of whom are having to reconsider how much water they use and how they use it in the wake of an ongoing megadrought that arrived at the beginning of this century. The changes are no longer in the "let's-discuss-this" phase as the federal government threatens to impose up to a 40 percent cut in river water allocations over the next 10 years if the seven western states—Colorado, New Mexico, Wyoming, Utah, Arizona, Nevada, and California—and the 30 recognized tribal jurisdictions with water rights don't agree among themselves about how to divvy up the dwindling Colorado River.
There isn't as much water as there used to be and that means that not everything people are using water for now will get its previous allotment. No doubt the volume of water representing the 52 percent of the total river withdrawals currently taken for agriculture could be reduced through conservation and efficiency measures. But it turns out that "conservation" in some instances might mean simply leaving fields unplanted for lack of water. And, it's not as if efficiency measures haven't already been implemented as irrigated agriculture in the Colorado basin has been transitioning to the much more efficient drip irrigation away from traditional surface irrigation. I could not find any statistics for this, however. So, it's not clear how much more water savings could be achieved through the installation of additional drip irrigation in place of surface irrigation.
Then, there is the 18 percent of the water withdrawals currently going to municipal water systems. The people in those cities have taken seriously the need to reduce water use. Even though those systems now serve 24 percent more residents today than in the year 2000, those systems use 18 percent LESS water. How much further could these cities reduce water consumption? It's almost certain that the easiest forms of reduction have already taken place. The next leg down in water consumption will be harder.
