>> Emergency crews in Northern California, on Monday, working to seal a crumbling spillway to the tallest dam in the U.S. that threatens to flood the cities below it. And they're competing with the weather as more storms are forecast for later this week. Nearly 200,000 people ordered to evacuate on Sunday.
And as of Monday afternoon, that evacuation is still in effect although the situation at the dam has stabilized for now. So how did it all happen? Reuters Sharon Bernstein is at the reservoir.>> One day last week, amid lots and lots of rain, the spillway which is basically a route for water to be released from the dam and go downstream back into the river developed a huge hole 250 feet across.
When engineers slowed down the rate of water going through that stowaway as a way to try to protect it. The water in the river in the lake grows and it poured down an emergency spillway, which then it started to fail.>> The emergency spillway was used for the first time since it was built half a century ago.
>> It's very much a fluid and dynamic operation that is going on out there. When you try to factor in what we're dealing with with Mother Nature, it's hard to look at a crystal ball and predict how that's gonna evolve.>> Orrville last a ghost town since the evacuation and thousands of residents are hold up in temporary shelters.
>> I just got a text message and then alerting saying get out as fast as you can. And there's fire trucks that are going up and down our street saying evacuate.>> The goal now is to lower the water level of the reservoir by 50 feet to prevent it from spilling over again.
At the failure of the emergency spillway officials fear could unleash a 30 foot wall of water on Orrville