One of the oddities of Southern California is that the weather hundreds of miles distant has more effect on its water supply than anything happening locally.
The torrential rains washing across the region aren't filling the big reservoirs that Southern Californians rely on because those reservoirs aren't here -- they are in Northern California and the Colorado River Basin, fed by snowmelt from the Sierra Nevada and the Rockies.
"We always have to look hundreds of miles away to see what the true impact is," said Bob Muir of the Metropolitan Water District of Southern California, the region's major water wholesaler. "Something that is running through Southern California and wreaking havoc doesn't mean gold for our water supply future in Northern California and the Colorado River."
But although those faraway river basins aren't as soggy as Southern California, they also are being hit by storms, promising some relief from a severe drought that has drained western reservoirs for the last five years.
For the first time since 1999, hydrologists in the upper Colorado River Basin are this year predicting near-normal water flows into Lake Powell, one of the West's biggest reservoirs and the scene of dramatically dropping water levels recently. If conditions hold, its level could rise by 30 to 40 feet this spring and summer, with runoff from melting snow in the Rockies.
"We're not having the biblical-proportion storms you're getting, but we're having lots of storms and the snowpack is 132% for this time of year," said U.S. Bureau of Reclamation hydrologist Tom Ryan, who monitors the upper Colorado River Basin.
Even with normal inflows, Lake Powell will be no more than half full: "The good news about Colorado River reservoirs is they can take a long drought. The bad news is they take a long time to refill, so with one good year, we can't sit back and say we can relax," said Ryan. "It's too early to celebrate. But the trend is very good."
Downriver at Lake Mead, which receives water from Lake Powell and supplies Southern Nevada and Southern California, water levels are rising a bit as storms dump water into Colorado tributaries and lessen irrigation demands, allowing operators to reduce dam releases.
In Colorado, where the river's headwaters rise, the snowpack is 99% of average, the best the state has experienced since the start of the western drought five years ago. Arizona and New Mexico are also getting the tail end of some of Southern California's storms, giving some relief to those parched states.
