The December storm that left thousands of British Columbians without power over the holidays was the "most damaging storm" in the BC Hydro's history, according to a new report released by the utility.

A powerful windstorm ripped through southern B.C. on Dec. 20, with winds of up to 100 km/h battering parts of the province, sending branches and outdoor structures flying and uprooting decades-old trees.

According to the report, more than 750,000 BC Hydro customers were left without power. The storm had more impact than the Lower Mainland's August 2015 windstorm and the 2006 windstorm that devastated Stanley Park.

Many customers waited days for power to be restored as crews scrambled to repair the damage.

Biggest mobilization

Mora Scott with BC Hydro said cleaning up after the storm required the biggest mobilization of people, equipment and materials in the utility's history.

Nine hundred field personnel worked to repair more than 1,900 spans of wire, 390 power poles, 700 cross-arms and 230 transformers that were damaged as a result of the winds.

Personnel were also brought in from out of province to help get customers back on the grid.

BC Hydro has in-house meteorologists to track and anticipate storms.

Scott said this storm was particularly destructive because of several environmental factors.

"First, the winds came from three different directions," she said.

"There was also more than 40 millimetres of rain in some areas in the weeks before the storm hit, which destabilized a lot of otherwise healthy trees, and wind speeds in some areas topped 100 km/h."

High winds brought down trees across B.C.'s South Coast. (Shane Mackichan )

911 operators 'overwhelmed'

According to the report, BC Hydro reconnected more than 550,000 customers in the first 24 hours, but thousands more waited days over the holidays for their power to be restored. All customers had power back by midday Dec. 31.

Scott said BC Hydro is now looking into what can be improved for future storm response plans.

"In this case some customers did experience challenges when trying to report downed lines to 911. Their operators were overwhelmed in certain areas. We also heard from customers that they had trouble finding information about their specific outages," she said.

"Those are two things among other things that we'll take away and work on improving from this storm."

BC Hydro is still tallying the total cost of cleaning up after the storm.