VANCOUVER - Officials in communities along the B.C. rivers expected to flood this week are confident that prevention work that has been done will prevent a major disaster.

Provincial officials warned Saturday that three northern B.C. rivers will reach flood levels by Wednesday as rain combined with warm weather continues to melt record snowpacks.

BC Environment issued a high streamflow advisory on Sunday for the North Thompson River upstream of Kamloops.

The North Thompson has been rising slowly for the past three days as a result of hot weather and accelerated snowmelt.

Flooding is predicted from Sunday into Monday for low-lying sections of the river upstream of Kamloops which don't have the protection of standard dikes. A similar advisory was also issued for the Slocan River in the Kootenay region, with flooding expected by Tuedsay.

Allan Chapman of the River Forecast Centre said people could be forced from their homes in the nothern community of Smithers as early as Tuesday.

Chapman said the Upper Fraser, the Bulkley and the Skeena Rivers will be above local flood stages this week. The Upper Fraser River in the Prince George and Quesnel regions is expected to hit flood level by Sunday night or Monday. It could stay there for a week or more.

However, Quesnel Mayor Nat Bello said he's confident that the work that's being down will protect his city from damage.

Bello said two 600-metre-long dikes have been built in the last few weeks to try to minimize rising water levels. He said the city has 15,000 sandbags ready to be distributed.

Bello said about 200 homes and businesses lie along the flood line but doubts that many are in harm's way.

Flood-level flows are expected on the Bulkley River near Smithers by Wednesday or Thursday and on the Skeena River through Terrace by next weekend.

Smithers Mayor Jim Davidson, like Bello, is optimistic. He said the city is ready to deal with an overflow of the Bulkley River which is running at "high normal."

"It does depend on the rain," he said.

Chapman said the Lower Fraser River could reach levels at the Mission gauge not seen since 1972. Those high flows could happen by June 9.

Bryon Simons of the province's Water Stewardship Division said local authorities have been working on dikes along the Lower Fraser to prevent flooding.

Local governments have the responsibility for any evacuations as a result of rising waters, but Jim Whyte of the Provincial Emergency Program said regional emergency centres have been activated and will remain in operation until the flood threat ends.

He said local governments have been advised of the increased risk for flooding so they can assess the threat levels to people in their areas.

He advised people in areas threatened with flooding to keep in touch with their local governments to find out what to do as water levels rise.

He said the areas most at risk are those around Prince George, Smithers and Kamloops which have not been protected by dikes.

Warm weather above 30C prevailed throughout B.C. on Sunday but rain is forecast for the rest of the week for much of the areas threatened by floods.

With the threat of flooding becoming more likely as spring progressed, the provincial government committed $33 million for anti-flooding initiatives throughout the province.

Snowpacks in British Columbia run from 83 to 165 per cent of normal, the highest being in the Nechako, Peace, Skeena, Nass and Bulkley regions.

About 3.5 million sandbags have been distributed throughout the province.

The lack of diking is also a cause for concern for dairy farmers in the Fraser Valley, especially in the areas of Agassiz and Glen Valley areas.

On Saturday, the provincial government started a program for voluntary relocation of thousands of dairy cows from areas where there is risk of flooding in the Lower Mainland.

The B.C. Milk Producers Association has warned its members to find alternative accommodation for cattle.

"Do not wait until the last minute to move your animls," an association advisory says. "If you wait until an evacuation alert/order is issued by local government, it will likely be too late to move your livestock."