In proposing two big, expensive dam projects this week, Gov. Arnold Schwarzenegger made a novel argument to justify the old-fashioned public works projects.
Advocating $4 billion in bonds to build reservoirs in Northern and Central California, the administration emphasized not population growth or the specter of future drought, but global warming.
As temperatures rise, California's mountain snowpack will shrink, leaving a storage void the administration says should be filled in part with new reservoirs.
"This administration is taking the lead in this country to deal with greenhouse gases," state Department of Water Resources Director Lester Snow said. But "no matter what we do now, we continue to have changes in snowpack and runoff patterns."
Each 1-degree rise in temperature pushes the mountain snow line 300 feet higher, meaning that as California warms, more precipitation will fall as rain in winter storms and less as slow-melting snow, increasing the flood threat and making it harder to capture mountain runoff.
"The forecast -- and these are fairly conservative forecasts," Snow said, "is that by 2050 we will have lost 25% of the snowpack in the Sierra.... If we don't take management action to accommodate that, we will wind up with both flood and water-supply issues."
GOP-backed administration proposals for new water storage projects sank last year amid Democratic opposition, and dam proponents said the chances of getting the reservoir plans through the Democrat-controlled Legislature this year are slim.
"I think we know a bit more about the effects of climate change in California," said Steve Hall, executive director of the Assn. of California Water Agencies, which supports new reservoirs. "But in the end I'm not sure it is enough to convince a majority of legislators to vote for it."
Both proposed reservoirs have been under consideration for years.
One would dam canyons and flood 14,000 acres of ranch country, including the tiny Colusa County settlement of Sites, 77 miles north of Sacramento. To lessen environmental damage, the reservoir would not be constructed on the Sacramento River but some 16 miles to the west.
Existing irrigation canals or a new billion-dollar pipeline would carry water from the river to the reservoir, which would hold roughly 1.8 million acre feet of water, less than half the capacity of Shasta Lake, the state's biggest reservoir.
