It's happened because of thunder and rain storms, which hammered the Interior Saturday and dumped in one day as much rain as some communities see in an entire month.
In Sicamous, about 500 kilometres northeast of Vancouver, the resulting downpour contributed to what officials have called a "flash flood," forcing leaders to issue a local state of emergency and evacuate as many as 350 people who were cut off after roads and bridges were damaged.
Near Nelson, a 71-year-old man was reported missing after a bridge washed away, prompting Justice Minister Shirley Bond to warn people to be vigilant and use extreme caution near rivers and streams.
For the communities along the lower Fraser River, though, the worst is yet to come, warned one official, who predicted another surge of water from the province's north is expected to arrive next weekend.
"We're staying on high alert, and we really need people to stay very, very safety conscious in this next week," said Bond.
"Stay away from flood waters, don't underestimate the swiftness of the water because flooded rivers and streams are unbelievably unpredictable, as we're all learning."
Don't walk on dams or dikes and don't let children in or near any floodwaters, she added.
Bond said the 71-year-old man who was swept away after a bridge washed out lived in the Crescent Valley near Nelson, about 450 kilometres east of Vancouver.
Scott Spencer, a spokesman for Nelson Search and Rescue, confirmed Sunday that a body had been recovered several hundred metres downstream from where the man was last scene.
At one point Saturday, Bond said she and her family found themselves on the other side of a mudslide on Highway 16 East, which is in the province's northwest.
Mudslides were also a problem near Revelstoke, in the province's east, blocking two sections of the Trans-Canada Highway on Sunday, according to a provincial government website.
Behind the bad weather, especially the thunder in the Interior, was a low-pressure system off the coast and hot air in Alberta, said Doug Lundquist, an Environment Canada meteorologist.
He said between 30 and 45 millimetres of rain fell on the Interior on Saturday, and that's as much as many communities receive in an entire month.
Based on radar, though, the actual amount of rain to fall east of Kelowna and into the Shuswap could have been as much as 60 to 80 millimetres, he said.
Watching those heavy rains fall in Sicamous and the resulting wave of destruction was local resident Gary Benz.
"It was astounding," said Benz, who lives by a creek that burst its banks. "I've never seen anything like it. Watching 30-foot chunks of bank drop into the creek, with trees ... going down and snapping like matchsticks.
"It was crazy. I've never seen anything like it. I hope I never see it again, either."
At one point the problem was so bad that a waterfall had formed in his own carport, said Benz.
Local resident Bernhard Kramer said he saw waters swamp several trucks at a vacation property and damage some nearby structures.
Also damaged were at least two bridges, stranding several residents, said fire Chief Brett Ogino.
"There was definitely reports last night (Saturday) of homes being flooded," he added. "And most of those people were evacuated out."
A reception centre is running at a local seniors' facility, he added, and a second evacuation had started Sunday morning.
But the rushing waters also appear to have damaged the local highway in two or three places, added RCMP Const. Pat Pyper.
"We are sending SAR into the areas, search and rescue people, and they are going to be going door to door," he said, adding that officials planned to use a boat to evacuate residents in one area.
Municipal officials have declared a local state of emergency and issued a do-not-use water order for one water system and a mandatory water-conservation notice.
The scope of the damage became evident Sunday afternoon as emergency officials began evacuating residents in Sicamous and the 2 Mile area.
"In the 2 Mile area and the District of Sicamous, up to 50 people have been evacuated," said Corey Paiement, information officer for the Shuswap emergency operations centre.
"In the Swansea Point area of the Columbia Shuswap Regional District that evacuation has just started recently and at this point it's estimated there may be up to 300 people that will be evacuated from that area."
Chris Duffy, executive director of emergency co-ordination for Emergency Management BC, called the incident a "flash flood."
He said at least four vehicles were washed into nearby Mara Lake and houseboats were also damaged.
Duffy said emergency officials around the province are watching developments.
He said Emergency Management BC's 24-7 co-ordination centre is operational, as is the provincial emergency co-ordination centre.
As of Sunday afternoon, four regional emergency co-ordination centres were running, he said.
On the local level around the province, 21 emergency operations centres were running, and there were four declarations of local states of emergency, said Duffy.
He said there were also five evacuation orders and 17 evacuation alerts.
In the meantime, Dave Campbell, head of the B.C. River Forecast Centre, said he expects the lower Fraser River to hit its highest levels since 1972 when a surge of water from the north makes its way south next weekend.
Campbell said he predicts the river could reach a flow of 13,000 cubic metres a second at Hope and a height of seven metres at Mission.
On Saturday morning, the flow was 11,700 cubic metres a second at Hope, and Sunday its height was 6.4 metres at Mission.
"I will caution that while we are expecting to see a bit of a lull in the middle part of the week, that we are expecting this additional surge next weekend on the Friday to Sunday period, and so not to be lulled into thinking that the sky is as clear and that things are improving," said Campbell.
"We do have this trend coming towards us."
--- by Keven Drews in VancouverSuggest a correction