ROBERT SIEGEL, host:
From NPR News, this is ALL THINGS CONSIDERED. I'm Robert Siegel.
MELISSA BLOCK, host:
And I'm Melissa Block.
Sunny and dry Southern California is home to thousands of swimming pools and lush, green lawns. But here are some surprising numbers. Since 1990, the population of the Los Angeles region's water district has grown by four million people. And in that time, water consumption hasn't increased at all. That's because the district got people to start using water more efficiently. Now, the region faces a looming threat to its water supply - climate change.
KQED's Rob Schmitz reports.
ROB SCHMITZ: If you want to better understand how California's water supply will be affected by climate change, conduct this simple experiment. Get a paper cup, go to the fridge, and fill the cup with ice.
(Soundbite of ice dispensing)
SCHMITZ: Now poke a hole in the bottom of that cup and wait.
(Soundbite of clock ticking)
SCHMITZ: While you're waiting, think about the ice in that cup as winter snow in the Sierra Nevada mountain range. The Metropolitan Water District of Southern California has used this snow to supply more than 18 million people with water.
Jeff Kightlinger is the district's general manager.
Mr. JEFF KIGHTLINGER (General Manager, Metropolitan Water District of Southern California): The great thing about snowpack is it's like a reservoir just - it melts slowly, gradually as the weather heats up. And we can build our system, and our canals, and our pipes, you know, a smaller size, and take that water as it melts.
SCHMITZ: Do you still have that cup of ice?
Well, mine's starting to slowly drip from the hole in the bottom.
(Soundbite of dripping water)
SCHMITZ: Now, scientists say that if carbon dioxide emissions continue at their current rate, temperatures will rise, and this snowpack throughout the Sierra will be reduced by 90 percent by the end of the century. Snow will become rain. And that dripping you just heard will sound more like this.
(Soundbite of pouring water)
SCHMITZ: This is the future the water district's Kightlinger is preparing for.
Mr. KIGHTLINGER: Now, if you have this much more, you know, sheet-type action -where the water is just coming down, and you have to move it and move it quickly - you have to larger facilities, larger pipes, and you need more storage.
SCHMITZ: This type of future has prompted Southern California's largest water distributor to spend over $1 billion on a gigantic pipeline. It's called the Inland Feeder. At the foot of the San Bernardino Mountains, a huge concrete tunnel protrudes from a brown rock wall. It's hot and dusty. A group of us in hardhats, orange vests, and boots descends a flight of stairs.
I'm standing at the entrance to the western section of the Inland Feeder tunnel. I'm about to get on a train that's going to take me two and a half miles underneath the ground.
(Soundbite of passing train)
SCHMITZ: This train won't be here in a couple of years. That's because it won't be a tunnel anymore. It'll be a huge water pipe. Its large circumference - it's 12 feet high - will accommodate a lot of water. It's designed for a future of isolated storms upstream that'll dump much heavier volumes of water than today's storms. This 44-mile pipeline will carry water from the western Sierra down to the huge local reservoir.
John Bednarski(ph) is the project manager.
Mr. JOHN BEDNARSKI (Project Manager, Inland Feeder): We'll be flowing at full capacity of 1,000 cubic feet per second of water or the equivalent to filling Olympic swimming pool in two seconds.
SCHMITZ: That'll triple the capacity of moving imported water to Southern California. Climate change expert and U.C. Santa Barbara professor Bob Wilkinson thinks projects like the Inland Feeder are good ideas in the face of climate change. But he points out, Californians would also do well to focus on the water storage capacity we have underneath our feet.
Professor BOB WILKINSON (Environmental Studies, University of California, Santa Barbara): The myth has been perpetuated that Southern California is a desert. There's no water in Southern California. It's all imported from somewhere else. And without that, everything would dry up and blow away.
SCHMITZ: In fact, half the water Southern California uses is local groundwater, that is, water that's naturally stored in the aquifer, which is made up of water permeable gravel, sand or silt. The aquifer acts like a big sponge absorbing rainwater and snowmelt from the surface. But L.A. has been drawing this water at a faster rate than the aquifer can naturally be replenished. To refill it, Wilkinson says, Los Angeles just has to conserve more water. He says that's what water officials should be concentrating on, not reservoirs or dams.
Prof. WILKINSON: The largest new water supply for California will be coming from urban water-use efficiency.
SCHMITZ: In other words, giving incentives for responsible landscaping and fixing leaky plumbing. Another incentive, says the district's Jeff Kightlinger, will soon be water bills that'll cost the same as cable television bills - a not too gentle reminder that climate change comes with a cost.
For NPR News, I'm Rob Schmitz in Los Angeles.