CALIFORNIA—Over the weekend, tens of thousands of residents were forced to evacuate their homes when water from the storm-swollen Oroville Lake spilled down the unpaved emergency spillway causing heavy erosion and raising flood concerns for the Oroville Dam, which is the largest dam in the country, at over 770 feet tall.

“Oroville Dam operators, quickly running out of options, said they’ll ramp up releases on the damaged spillway this morning even though a middle section of the spillway is gone. Stay tuned right here for live updates on the spillway and what DWR’s plans are in the face of flood risk,” stated a post from the Oroville Dam Facebook page on Sunday, February 12.

In 2005, environmental activists and local government officials asked state and federal regulators to require that the California Department of Water Resources “armor” the hillside and reinforce it with concrete or boulders to prevent catastrophic flooding.

State and federal regulators dismissed those fears saying they were confident the hillside was stable and didn’t need to be reinforced with concrete.

“I think the warning that was given should have been taken with the utmost seriousness,” said Bob Wright, an attorney at Friends of the River to NBC 4 News.

Governor Jerry Brown said he had not known of the warnings about the emergency spillway.

“I’ve been in close contact with emergency personnel managing the situation in Oroville throughout the weekend and it’s clear the circumstances are complex and rapidly changing. I want to thank local and state law enforcement for leading evacuation efforts and doing their part to keep residents safe. The state also is directing all necessary personnel and resources to deal with this very serious situation,” said Governor Brown in a statement.

Written By Darylese Shook and Casey Jacobs