Catastrophic flooding is possible in British Columbia's Fraser Valley this year, because an estimated 150 kilometres of dikes along the banks of the Fraser River are at risk, officials say.

If the river does overflow, thousands of people would have to leave their homes and hundreds of square kilometres of farmland would be under water.

Early settlers recognized the potential of the fertile soils along the Fraser for growing food. Busy harbors and towns grew nearby because of easy access to inland and marine transportation routes. This intensely used river is home to five deep-sea port facilities, a ferry terminal, several fishing boat basins and numerous marinas and floating homes.

Over 200 companies, including several large woodand fish processing facilities operate on or near the Fraser. It also accommodates the largest log booming grounds in the world.

The Fraser River is the largest river in British Columbia, over 1378 kilometres. long. Its headwaters are at Mount Robson in Jasper National Park. The drainage of the entire river basin (watershed) is nearly one quarter of a million square kilometers -- larger than the area of Great Britain.

The flood of 1948, the last major flood in the Lower British Columbia Mainland, flooded the area with almost 8 metres of water, just 80 kilometres from Vancouver. The 1948 flood claimed 10 lives, destroyed or damaged 2,300 homes and caused $20 million in damage - about $140 million in current dollars.

Total water flows in the Fraser River this spring are predicted to reach 94 per cent of 1948 flood levels.

Although some dikes have been improved, the potential for disaster lingers if further prevention measures aren't taken, provincial officials said yesterday .

The worst flood in the area's history was in 1894, when water levels reached 7.92 metres. A federal-provincial Fraser River flood-control program has rebuilt about 250 kilometres of dikes to withhold water levels as high as those in the 1894 flood. But officials say an estimated 150 kilometres of dikes in the Lower Mainland and Fraser Valley could not hold back that much water.

Should high-water levels persist for abut two weeks, the dikes would be at serious risk of becoming saturated and breaching (breaking), or allowing seepage to escape through the soil and bubble up around homes and buildings.

"This can be quite dangerous if not controlled," says Environment Ministry spokesman Neil Peters. "There is always the possibility the dike could fail."

Ultimately, the water levels depend on the weather. If the snow melts gradually, there would probably be high, but safe, water levels. A very rapid melt could result in major flooding. "The worst-case scenario is a month of scorching weather," Peters said. "We would approach 1948 or 1894 levels."

River levels are unlikely to peak before mid-May at earliest, and the peak flows might not occur until late June.

Even if 1894 river levels aren't reached this spring, it's just a matter of time before they are, Peters says. "We know this flood will occur sooner or later."

2. What grew nearby because of easy access to inland and marine transportation routes?