Where is Our Water Going to Come From?

Cathy Wilson
Los Alamos National Laboratory
 

The Earth is called the "water planet”. Our planet is unique in our solar system because of its abundant water in our oceans, rivers, lakes, atmosphere, soil, and rock formations. From space it looks like we have more water than we could ever possibly consume: about 320 million trillion gallons! But only about 0.05 percent—that found in our lakes, rivers, and shallow groundwater reservoirs—is suitable for human needs. This usable water—slowly replenished by precipitation on a range of time scales—is not uniformly distributed, either. Some places have lots of water while other places have very little. Even where water is abundant many people have no access to clean water due to pollution or to lack of power and infrastructure for pumping, water treatment, and distribution. In fact, more than half of the world’s population lacks safe drinking water.
 
Fortunately for us, most people in the US now have access to clean water. Indeed, most of us take it for granted that we will have all the clean water we need, whenever we need it, and not just for the drinking water on which our lives depend, but for the myriad things in our society that we need water for, such as cleaning, growing food, making all kinds of products, and producing power and fuel. Most of us probably feel that access to whatever water we need is one of our inalienable rights! But perhaps we should not be taking water availability so much for granted. Especially for those of us who live in arid regions, there are some dark clouds on the horizon.
 
One reason for concern is the effects of climate change, particularly long-term trends in temperature in the atmosphere and oceans over decades and centuries. Some of the consequences of climate change that are predicted for the Western US, including New Mexico, are hotter temperatures, long term reduction in the amount of precipitation that falls as snow, and warmer spring weather that melts snow earlier and faster. But the design of our water infrastructure, especially the size and number of the water reservoirs across the country, was based on the concept of a “stationary” climate which means: the future looks like the past. Our designs do not account for climate change.
 
Why does this matter? Many of our most important reservoirs, those that supply water to tens of millions of people, are designed to catch, hold, and release runoff from snow as it slowly melts over the late spring and summer. If snow melts quickly in the spring, then it floods the reservoir and has to be released during the spring floods, rather than slowly through the warmer summer months when it is needed for farm irrigation or power generation during times of peak demand. This is a big deal! Hundreds of millions of dollars are being spent in the US to understand and plan for these changes so we don’t run out of water—and food and power as well. So in New Mexico, as well as many other parts of the world, water resources are under increasing stress due to climate change. This stress affects all living things that are dependent on rivers and lakes for water supply or habitat.
 
But here in the Southwest there is another source of stress on our water resources, and it is getting more acute as our population increases and there is more and more demand for water. It has to do with the question of who legally has the “right” to water supplies. In much of the western US, the use of water in rivers is governed by the doctrine of “prior appropriation”, dating from the 19th Century. The essence of this doctrine is that, while no one may own the water in a river, all persons, corporations, and municipalities have the right to use the water for beneficial purposes. Who gets access to water, how much they get to use, and when depends on the principal of "first in time, first in right." The first entity (farmer, city, power company, etc.) that makes use of a quantity of water on a river obtains the most senior right to that amount of water and has first access to that water...forever! What happens during a drought when there is only enough water in a river for the most senior water right holder, and the second, third, fourth, … , nine hundred and ninety-ninth water right holder needs water? What would you do if you were a junior water right holder, you paid money for a water right, your livelihood depended on getting a certain amount of water, and the river manager told you to turn off your pump? Would you call your congressman, hold a demonstration, try to get “number one” to share, pump the water anyway (cheat), start a water war?
 
These are problems on the horizon now, but are going to become big issues sooner than you think. New Mexico may have already over-allocated its water resources by a factor of three. How will we address these problems in New Mexico, the USA and the world? Can we solve them with water efficiency technology? More dams? Changing water rights? Tougher regulation of industry? Taking personal responsibility for reducing our individual water footprint? This Café will explore these problems and potential solutions as we answer the bigger question: “Where is our water going to come from?”