<sod >At least 130,000 people were asked to evacuate their homes in Northern California after authorities warned an emergency spillway in the country's tallest dam was in danger of failing Sunday and unleashing uncontrolled flood waters on towns below.< eod>< sod > At least 188,000 people were under evacuation orders Monday as crews raced against time to keep an emergency spillway at the country's tallest dam from failing and potentially unleashing uncontrolled floodwaters on towns below.< eod>