Update 3: Here is the question officials are asking: can they drain the Oroville dam fast enough before the Wednesday storm? As the SacBee writes, water is flowing out of Lake Oroville's main spillway fast enough to cause lake levels to drop by up to 30 feet before the next storm Wednesday night. Officials hope that will be enough. Lake Oroville can fill fast during a big storm. During storms from Monday of last week through Friday, lake levels increased by 50 feet.
The main factor in how fast the lake drains continues to be the condition of the main spillway. Officials said Monday morning that the main spillway had not further deteriorated despite huge outflows cascading over it Sunday afternoon and evening. The more water drained from the lake by the next storm, the less chance that the lake again will fill to the point that activates the emergency spillway. Erosion on the emergency spillway Sunday night created the need to evacuate nearly 200,000 people.
With 100,000 cubic feet per second of water flowing out of the lake, lake levels were dropping about one foot every 3 hours on Monday morning, state figures show. That translates to a drop of about 120,000 acre-feet every 24 hours. At current pace, the lake will fall to about 400,000 acre-feet below its emergency spillway by Thursday morning. To get the lake back to the levels normally mandated for flood control, it would need to fall by about 700,000 acre-feet.
Officials have more modest goals. They said Sunday night that they hope to drain the lake by 20 to 30 feet by the next storm. At current pace, they will hit that target.