What specific impacts are we seeing now?
Bruce Hallin If you look at the tree-ring studies, stream-flow reconstructions, what they're telling us in Arizona is that the year 2002 was the lowest stream flow ever recorded since the 1300s.
Mulroy A lot of the storage for the Colorado River system is in snowpack, and that gradual melt of the snow isn't happening anymore.
Gleick The Colorado worries me the most. We know we've already given away too much water in the Colorado. We have to fundamentally change our basic assumptions, and we aren't doing that.
Don't a lot of people think, Well, if we run short of water in Los Angeles or Phoenix, we can pipe it in from Alaska or Canada?
Barry Pumping water takes enormous volumes of electricity. Something like 25 or 30 percent of all the electric consumption in California is attributable to the pumping of water.
Hallin Water requires energy, and energy requires water.
So is water the new oil?
Gleick Oil is not renewable; water is. That's an advantage. There are substitutes for oil, though. And there are no substitutes for water. That's a big disadvantage.
But on a per-capita basis, we use less water than we did 20 years ago, right?
Hallin I look at the city of Phoenix, and over the last 10 years, we've had close to a 300,000 increase in population. But water demand overall has remained constant. We have better technologies; people are more cognizant of their water use.
Gleick That's true in Los Angeles and San Francisco.
Hallin We've had new plumbing codes that require these low-water-use fixtures in Arizona for over 20 years. We've taken a long-term planning viewpoint because we know we live in an arid environment and we will be facing a drought.Even so, people argue that the West will always have water problems because we've built big cities like Las Vegas and Phoenix in the desert.
Mulroy You know what? Las Vegas exists. It's where the jobs are. It's where the people are. And southern Nevada industry is the most water-efficient industry there is.
Hallin People like living in the desert. It's a very good quality of life.
Gleick It's not a question of taking down Las Vegas or Los Angeles or Albuquerque or Phoenix and building them back somewhere where there's water. That horse has left the barn.
What about dams? It's argued that because of global warming, we'll need to build new dams to store more water.
Barry Historically in the West, one of the answers to a highly variable natural supply of water was water storage. You stored water in times of plenty to get through times of drought. If we're going to see more variation, maybe we need to think about additional storage.
Gleick Dams brought enormous benefits to the western U.S. They also brought some unexpected costs, mostly environmental.
Amy Souers Kober People ask American Rivers all the time, "Well, are we going to need to build more dams?" And I think that that's not even the right question to ask right now.
At the same time, there's a strong push to tear down some dams.
Gleick People don't know this, but in the United States, more than 500 dams have been removed over the last 10, 15, 20 years. Almost all of them small, almost all dangerous, because they were badly built or environmentally destructive.