"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."
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http://www.latimes.com/news/local/la-me-water11jan11,1,2194840.story?coll=la-headlines-california