About 115-thousand northern California residents are being kept away from their homes as flooding continues to devastate large areas of the western United States.
Many people are staying in shelters set up in schools, churches and Army bases Saturday.
Helicopters rescued marooned motorists and plucked stranded farmers from rooftops, sometimes under hazardous flying conditions.
Governors of five western states have declared a state of emergency in more than 80 counties after being deluged with snow and rain in a series of non-stop storms that began on December 26th.
At least 23 deaths have been blamed on the storms.
President Clinton declared northern Nevada a major disaster area Friday, while the governors of California and Idaho appealed for federal disaster aid.
The storms have blocked major highways in California, Idaho, Nevada, Oregon and Washington.
Boulders the size of a house crashed onto a Sierra Nevada highway.
California's scenic coastal Highway One was cut off in at least four places.
Early Saturday, a levee broke in a rural area west of Modesto, 130 kilometres (80 miles) east of San Francisco.
Modesto itself is suffering its worst flooding in 40 years after the Tuolumne River, gorged by water rushing out of the Sierra Nevada, washed into the southern edge of the city five metres (15 feet) above flood level.
About three-thousand Modesto residents have been evacuated, while the sewage treatment plant has been put out of service.
Some casinos in Reno removed sandbags and reopened, as did the Reno/Tahoe International Airport after removing up to one metre (four feet) of water from the runways.
South of Reno, residents of the Carson Valley are mopping up after floods damaged at least 100 homes and turned the area into a vast lake.
Seattle had counted 97 mudslides by Friday afternoon, and at least 40 homes had been evacuated.
But the worst of the rains appear to be over.
Scattered light showers are forecast for this weekend over most of the west coast of the United States, with drier weather next week.