Tens of thousands of Californians faced an indefinite stay in shelters as engineers worked for a second day on Tuesday to fix the United States' tallest dam before more storms sweep the region.
After what looks set to be the wettest winter in Northern California following years of drought, more rain was forecast for as early as Wednesday and through Sunday, according to the National Weather Service.
Crews were working to shore up an overflow channel and drain the reservoir at the Lake Oroville Dam but authorities gave no indication of when it would be safe for people to go home.
Late on Sunday, about 188,000 residents were ordered to evacuate their homes in the Feather River valley below the dam, 65 miles north of Sacramento.
Authorities say they had averted the immediate danger of a catastrophic failure at the dam that could unleash a wall of water three stories tall on towns below.