Media playback is unsupported on your device Media caption What went wrong with US dam?

Authorities in California have lifted an evacuation order for some 180,000 people who live below the highest dam in the US, as fear of spillage receded.

Butte County officials said the residents could now return to their homes but should remain vigilant.

Their homes were in danger of being engulfed by water after the 770ft (230m) high spillways of the Oroville Dam were found to be damaged.

But the authorities have now managed to lower the water level in the dam.

At a news conference on Tuesday, Butte County Sheriff Kory Honea said Sunday's evacuation order had been changed to an evacuation warning.

This came after a significant amount of water had been drained from the dam.

The California Department of Water Resources was releasing as much as 100,000 cubic feet (2,830 cubic metres) of water per second from the main spillway to try to lower the lake's level and relieve the pressure on the spillway.

Officials had been telling residents for days that the damage was nothing to be concerned about, but then late on Sunday told them to get out within an hour.

They said they realised that both the spillway and its emergency counterpart were damaged and unable to cope with a deluge of rain and snow.

More rain is forecast for Wednesday and Thursday, which has led to some concern about whether or not the damaged spillway can withstand the pressure.

It is the first time that Lake Oroville, which lies 65 miles (105km) north of Sacramento, has experienced such an emergency in the dam's near 50-year history.

Correction 18 February: A picture in this article, now removed, was mistakenly identified as part of the Oroville Dam.