Abbotsford, B.C., officials 'very concerned' with up to 220 mm of rainfall expected through Wednesday

Vancouver -

Overnight rainfall in flood-ravaged Abbotsford, B.C., was no match for the city's fully operational Barrowtown Pump Station, but officials remain anxious about the forecast over the coming days.

Mayor Henry Braun said the atmospheric river that arrived on the South Coast Thursday delivered approximately 50 millimetres of rain, but that the Barrowtown floodgates remained fully open throughout the night, allowing the swollen Sumas River to continue emptying into the Fraser.

"Overnight conditions remained stable across the flood zone," Braun said at a Friday morning update.

"Despite this positive news, we remain very concerned about the coming weather events and the impact they will have."

The mayor noted that floodwaters in Sumas Prairie were dropping by up to eight inches per day prior to Thursday's storm, but only decreased by three inches over the last 24 hours while pumps grappled with a new influx of rain and river runoffs.

And the next two atmospheric rivers expected to reach the region Saturday and Tuesday could be significantly wetter.

"Current estimates are that we will receive between 90 and 120 millimetres Saturday and Sunday, with an additional 50 to 100 millimetres of rain Tuesday and Wednesday," Braun said. "Cumulatively, that is more water in total than the initial event, although over a longer period of time."

The historic storm that caused devastating flooding, landslides and highway washouts in B.C. last week delivered about 180 millimetres of rain to Abbotsford over about two-and-a-half days.

Braun has estimated the flooding caused $1 billion worth of damage in his city alone. Thousands of livestock also died as a result of the natural disaster, the scale and severity of which has been blamed on human-caused climate change.

The mayor said crews have been hard at work bracing for the next storms, and have completed repairs on the main portion of a dike that burst last week, sending water from the Sumas River gushing into Sumas Prairie.

Efforts continue to raise a further seven kilometres of dike along the river, which Braun estimated would be finished late Friday or Saturday.

Much remains out of local and provincial officials' control, however. Last week's flooding was exacerbated by water from the Nooksack River in Washington state, which has been surging once again.

The river is currently expected to reach "moderate flood stage" on Sunday, according to an update posted on the Whatcom County website Friday.

"Damage to levee systems from previous storms may result in greater impacts to the floodplain areas than would typically be experienced at these river levels," the county said, adding that the "potential also exists for this to impact Sumas."

Flooding in the city of Sumas could result in water spilling across the border into B.C., Abbotsford said in Friday evening update.

Given the forecast, Braun said he does not expect any changes to Abbotsford's existing evacuation orders before the middle of next week.

"We understand this is a difficult time for everyone impacted by this difficult situation," the mayor added. "Please know we are focussed on your safety and will continue to update you as we can."

Meanwhile, Canada Task Force 1 is continuing to perform rapid damage assessments in the city. More than 2,000 properties have been assessed so far, and the team is expected to undertake 1,000 more over the coming days.

With files from The Canadian Press