Heavy snow and rain pounded the western United States for a third day Sunday as state officials confirmed two fatalities from the storms that have pummeled the region.

California was drenched with up to 10 inches (25 cm) of rainfall in some regions as mountain communities in the east of state and neighboring Nevada were blanketed by nearly six feet (two meters) of snow in places, National Weather Service figures showed.

Around 110,000 homes and businesses remained affected by power outages across California, down from more than 800,000 on Friday when the worst of a series of storms slammed into San Francisco and its surrounding areas.

A spokeswoman with the California Governor's Office of Emergency Services said Sunday there had been two confirmed storm-related deaths.

A council worker in Yuba City north of Sacramento died after being hit by a fallen tree while a woman drowned after being swept away by floodwaters in San Bernardino County near Los Angeles, spokeswoman Jodi Traversaro said.

Rescue and emergency services were now on alert for possible mudslides in rugged regions devastated by last year's California wildfires, she added.

"What we are really concerned about are the areas affected by the wildfires. The ground has been absolutely saturated and it's not going to take a lot for debris flows or mudslides to occur," Traversaro told AFP.

"We are on heightened alert in those regions."

California Governor Arnold Schwarzenegger had declared a state of emergency in three counties to help combat storm-affected areas.

The Governors of Nevada and Oregon also declared states of emergency in regions including a town flooded by three feet of freezing cold water when a levee burst early Saturday.

Investigators in Fernley, Nevada, east of Reno, were continuing to probe the cause of the levee breach on Sunday, with local media reporting that burrowing rodents may have been to blame.

Around 3,500 residents were evacuated from some 800 homes to an emergency shelter following the incident early Saturday according to Nevada state police.