The uncertainty of Southern California’s water supply was the focus of the RAND Policy Forum on Thursday, April 17, as a full auditorium listened to RAND analysts and Jeffrey Kightlinger, general manager for the Metropolitan Water District of Southern California (MWD), discuss climate change and California’s water supply.
Senior Physical Scientist Robert Lempert explained that “future climate is going to be different – significantly different – than past climate,” though he could not predict exactly how. He displayed a graphic showing that summertime temperature change from 2000 to 2030 might vary from +0.1 to +2.1 degrees Celsius and wintertime precipitation might change over the same period from -19 percent to +8 percent. (If 2.1 degrees doesn’t sound like much, he observed that the temperature change from the Ice Age, when most of Canada was covered by nearly a mile of ice, to today was only eight to 10 degrees.)
“California has built the most extensive water retention, protection, and distribution system in the world on the assumption that future snowpack will be the same as in the past,” said Kightlinger. Although that assumption is now being questioned, there was some good news. Kightlinger reported that in the early 1990s there was 250,000 acre-feet of local water storage in Southern California; today there is 3 million acre-feet. And while the six-county area served by MWD has grown by four million people since 1990 (from 14 to 18 million), that larger population uses the same amount of water – so conservation is having an impact.
Santa Monica, he noted, uses 25 percent less water per capita than it did 15 years ago.
Addressing a question that came up during the City Council’s April 8 discussion on extending the city’s green building program to include single-family homes and duplexes, MWD’s Kightlinger reported that 80 percent of California’s water goes to agriculture, and the remaining 20 percent to municipal and industrial uses. Two-thirds to three-quarters of that 20 percent is residential usage, and at least half of that goes to watering lawns.
Agriculture has become more efficient in its use of water, the panel noted, decreasing its production of high-water crops like cotton and rice. “California produces over half the nation’s fruits and nuts” drew a laugh.
In response to a question about desalinization, Kightlinger said that there is a lot of opposition to such projects, and panel moderator and RAND Vice President Debra Knopman noted that the process is expensive. Kightlinger said that MWD’s price for water is about $550 per acre-foot, while desalinized water costs about $1,000 per acre-foot.
While the uncertainty of the future was the principal theme of the evening (“We’re not sure what we should be planning for,” said Kightlinger), the MWD general manager issued an urgent call for infrastructure investment in the Sacramento River Delta. “The infrastructure is over 100 years old,” he said, “and the Delta levees make New Orleans look state-of-the-art.”
