Don's Home Places USA California Sacramento River Basin Feather River
In 1961-1968 the Oroville Dam was constructed for water supply, hydroelectricity generation and flood control.

Oroville Dam is an earthfill dam and the highest dam in the US at 770 ft. It is 44 ft. higher than Hoover Dam.

A February 2017 storm caused damage to the main spillway and significant damage to an emergency spillway, threatening to cause a large breach in the dam.
A 30-foot "wall of water" could be sent rushing downstream if the eroding spillway were to collapse.
180,000 people were evacuated from Oroville south to Marysville. See map.
I would take 8-12 hrs. for the water to get to Yuba City about 35 miles away.

It was a warm system with snow levels as high as 8,000 ft. causing snow melt in addition to the rain runoff.

October - February 2016 was the wettest on record in Northern California with totals running at 200% or more than normal.

Jan. 31: Flows through the main spillway increase to more than 10,000 cfs as runoff into the river increases.

Tue Feb 7 - Reservoir releases through the main spillway are increased to 54,500 cfs to offset higher inflows from rainfall.
Department of Water Resources (DWR) discovers a large amount of debris coming out of the concrete-lined spillway and stops all releases to inspect the damage. Engineers discover a massive crater. Authorities decide to use the crippled spillway, but with reduced flows.

Thu Feb 9 - Water was flowing into the huge reservoir in Butte County at an astrounding 190,000 cubic feet per second — roughly the flow of the Mississippi River at St. Louis.

Fri Feb 10 - Engineers were releasing 65,000 cfs down the damaged regular spillway, slowing the lake’s rise just enough to prevent any flooding.

Sat Feb 11 - The water elevation in Lake Oroville reaches 901 feet, its full capacity, leading water to flow over the emergency spillway for the first time in its nearly 50-year history.
That spillway is not a concrete channel. It’s a hillside with trees and rocks that would have caused massive erosion into the Feather River, possibly triggering flooding in communities downstream.

Sun Feb 12 - Erosion begins to progress up the right side of the emergency spillway. Fearing the ground will collapse underneath a concrete slab holding water in the reservoir, authorities order a mandatory evacuation of 188,000 people in towns downstream.
DWR increases the primary spillway releases to 100,000 cfs to draw down the water level. Within hours, water stops flowing over the emergency spillway so experts can assess the erosion.

Mon Feb 13 Crews begin working around the clock to repair the eroded areas below the emergency spillway. Almost 200,000 people remain under evacuation order.
Debris fills a pool below the emergency spillway, forcing the closure of an underground hydroelectric plant.

Wed Feb 15 - Water levels have dropped by 26 feet.

Sat Feb 18 - DWR will decrease the flow of water in the Oroville Dam's main spillway from 80,000 cubic feet per second to 60,000 by Saturday morning, giving crews space to dredge debris from the diversion pool at the bottom of the spillway.
Inflow was down to 36,700 cfs.
Source: Timeline of problems at Oroville Dam - San Francisco Chronicle

oroville dam, emergency spillway

oroville dam, emergency spillway

Feather River Wildlife Area | CA dept of Fish and Wildlife
Oroville Dam flow slows, emergency spillway may not be used