An aerial view of the flooding in Vancouver Island's Cowichan Valley, where more drenching rains are predicted. (CBC)

Dozens of homes have water "up to the doorknobs" and others are under evacuation alert after heavy rain combined with high tides to flood low-lying parts of Duncan, B.C., an hour's drive north of Victoria.

Water streamed around a network of dikes built since the 1960s, when flatlands in the city and surrounding communities were routinely inundated.

The municipality of North Cowichan, which includes Duncan and has more than 27,000 residents, declared a local state of emergency after water from the Cowichan and Koksilah rivers and several creeks spilled their banks Friday morning.

"There's been high tides in the ocean which has not allowed the rainwater to drain away fast enough," public information officer Mark Ruttan said.

"We've had a couple of schools that have closed for the day and we've had to evacuate people out of their homes. That'll be about 300 homes."

Estimates put the number flooded homes at more than 50 in North Cowichan and more in Duncan itself, Ruttan said.

"There's a number homes that were flooded up to the doorknobs."

Provincial assistance available

The provincial government announced late Friday that it's approving disaster financial assistance for many of the flooded areas.

Eligible for the assistance are homeowners in the Comox Valley Regional District, Nanaimo Regional District, Cowichan Valley Regional District and Strathcona Regional District, according to a news release from the B.C. Solicitor General's Ministry.

Residents rescue a car from the flooded streets. (CBC)

Most of the trouble was in the Somenos Marsh area, just north of Duncan.

"It was an area that flooded years ago quite often before they put in these larger dikes," Ruttan said.

The dikes themselves have not been breached but there are gaps, he said.

Cindy Jones said she could see a lake of flood water across from the travel agency she manages. The nearby elementary and junior high schools are protected by dikes but were closed Friday.

"The road coming into my office is full of water," she said. "It's bad. I've lived in the (Cowichan) valley all my life and every so many years we get like this. We haven't been this bad for a good couple of years."

Periodic flooding a fact of life

Another longtime resident, retired woodworker Roger Stanyer, said the combination of low land, high tides and massive rainfall makes periodic flooding a fact of life in the area.

"It's certainly higher than normal," Stanyer said. "But not as high as it has been in the past, quite a few times."

A reception centre was opened for evacuees at a local community centre. Manager John Elzinga said about 100 people had registered.

A Cowichan Valley resident takes a trip through town in his canoe. (CBC)

Water levels started dropping Friday afternoon, but Ruttan said the evacuation order would remain in place and crews were sandbagging because more rain is forecast.

"It's a little drier now but we're expecting some more rain and probably Sunday we'll dry out a bit," he said. "But the longer-range forecast is for more rain next week."