Oroville evacuees Debra Walker wanders the fairgrounds at the Silver Dollar Fair evacuation shelter in Chico, Calif., on Feb. 13, 2017. Brian van der Brug | Los Angeles Times | Getty Images

Authorities lifted a three-day mandatory evacuation order in Northern California that had sent nearly 200,000 residents away following fears Oroville Dam's damaged emergency spillway might fail. Butte County Sheriff Kory Honea was the first to announce the order was lifted at a press conference Tuesday afternoon in Oroville. "We have concluded that it is safe to return," said Honea. The sheriff said he had received assurances from state and federal experts that the situation was now deemed safe. He said there's still "an evacuation warning" that considers the possibility that there could be future changes in the situation.

Specifically, Honea said engineers had reduced the level of the reservoir below the top of the emergency spillway so the erosion to the area in front of it could be halted. Further, the sheriff said the massive hole in front of the spillway was thoroughly inspected by federal and state experts and it revealed there was no erosion that compromised the overall integrity of the backup spillway. Also, he maintained that the concrete-lined spillway (even with its own erosion issues) still is able to provide significant outflows and lower lake levels while also reducing the chance of needing to use the emergency spillway. According to the California Department of Water Resources, other fixes at Oroville Dam — California's second-largest dam — included dropping sacks of rocks into the emergency spillway's crevice to prevent more erosion. The hole found Sunday in the emergency spillway — essentially a natural hillside of soil, rock and brush — led engineers to shift major water flows away from this unlined channel. The main spillway is damaged from significant concrete erosion but has still been releasing water this week. Frantic efforts continue to shore up the emergency spillway before a major storm reaches the Oroville area. "A lot of equipment and a lot of materials are moving around — from the ground and the air," said William Croyle, DWR's acting director. "This is an aggressive, proactive attack to address the erosion concern."