worried about this massive hole that's formed nearby. the oroville dam holds water back from lake oroville, now at record levels and in danger of spilling over after a series of storms. the 200-foot-long, 30-foot-deep hole is enormous, dwarfing the engineers who climbed in for a look this week. it eroded through the concrete spillway used to release water and keep the lake from topping its banks. >> this is a big deal. we're very concerned that we manage this properly to protect the public down below. >> reporter: here's the problem. if the spillway can't release enough water now, officials will have to try a never before used emergency spillway. >> we're monitoring 24/7. if any changes occur that will cause danger to public, we will immediately notify the public. >> reporter: officials stress, the dam is safe now that conditions are improving. the sky is clear and the rains have stopped. but they're keeping a close eye