Snowy spring raises runoff worries

Springtime snow and cold weather have combined to increase the spring flood risk in some B.C. watersheds.

That includes the lower Fraser River, where peak flow from runoff could equal the near-flood conditions seen last spring, according to the latest provincial government forecasts.

Snowpacks are not as high as last year’s record levels, but the late snow and unseasonably cold weather have combined to increase the volume and the chance of a heavy flow.

“We can expect very warm temperatures to occur once we hit the middle of May and early June,” Environment Minister Barry Penner said Thursday. “We could suddenly have a blast of hot weather, and then if that’s followed by heavy rainfall up in those mountain watersheds, then you get a large discharge.”

The ministry’s river forecast centre calculates that peak flow on the Lower Fraser could match last year’s peak of 11,000 cubic metres per second. River-side communities spent last spring strengthening their dike systems and watching nervously as record snow turned into a roaring torrent that barely stayed contained.

As of May 1 this year, snowpacks were 20 per cent above normal on Vancouver Island and on coastal drainages. The Upper Fraser and Peace were 116 per cent of normal and the North Thompson was at 114 per cent. Near-normal snowpacks were measured on the Nechako, South Thompson, Columbia, Kootenay, Okanagan and Similkameen.

The cold spring and delayed melting could result in above-normal water flows in late May and early June on the Upper Fraser, North and South Thompson, Skeena, Bulkley, Nass, Kootenay, Columbia and other rivers.

The Upper Fraser from Quesnel up to Prince George did reach flood stage last spring, as did the Nass, Skeena, Bulkley, Nechako and other rivers.

As the record snow accumulated last winter, the province launched an emergency $33 million program to strengthen dikes and other flood prevention works, and has since announced a budget of $10 million for the next 10 years to continue flood works.

Penner said he has been meeting with federal officials to encourage them to share the costs of the flood work, as they did by picking up half the cost of the 2007 works.

He’s also “very optimistic” the federal government will annnounce “something very soon” about matching the annual $10 million committed by the province - although it won’t likely come in time for this year’s freshet.

Gravel extraction from the Lower Fraser has also resumed after several years where little or no gravel was taken out. A large removal near Chilliwack was completed, stopping short of the 400,000 cubic metre target on the advice of environment monitors, Penner said.

That removal and a smaller one near the Agassiz-Rosedale bridge brought the province close to its target for relieving the accumulation brought down by each spring freshet.

Springtime snow and cold weather have combined to increase the spring flood risk in some B.C. watersheds.

That includes the lower Fraser River, where peak flow from runoff could equal the near-flood conditions seen last spring, according to the latest provincial government forecasts.

Snowpacks are not as high as last year’s record levels, but the late snow and unseasonably cold weather have combined to increase the volume and the chance of a heavy flow.

“We can expect very warm temperatures to occur once we hit the middle of May and early June,” Environment Minister Barry Penner said Thursday. “We could suddenly have a blast of hot weather, and then if that’s followed by heavy rainfall up in those mountain watersheds, then you get a large discharge.”

The ministry’s river forecast centre calculates that peak flow on the Lower Fraser could match last year’s peak of 11,000 cubic metres per second. River-side communities spent last spring strengthening their dike systems and watching nervously as record snow turned into a roaring torrent that barely stayed contained.

As of May 1 this year, snowpacks were 20 per cent above normal on Vancouver Island and on coastal drainages. The Upper Fraser and Peace were 116 per cent of normal and the North Thompson was at 114 per cent. Near-normal snowpacks were measured on the Nechako, South Thompson, Columbia, Kootenay, Okanagan and Similkameen.

The cold spring and delayed melting could result in above-normal water flows in late May and early June on the Upper Fraser, North and South Thompson, Skeena, Bulkley, Nass, Kootenay, Columbia and other rivers.

The Upper Fraser from Quesnel up to Prince George did reach flood stage last spring, as did the Nass, Skeena, Bulkley, Nechako and other rivers.

As the record snow accumulated last winter, the province launched an emergency $33 million program to strengthen dikes and other flood prevention works, and has since announced a budget of $10 million for the next 10 years to continue flood works.

Penner said he has been meeting with federal officials to encourage them to share the costs of the flood work, as they did by picking up half the cost of the 2007 works.

He’s also “very optimistic” the federal government will annnounce “something very soon” about matching the annual $10 million committed by the province - although it won’t likely come in time for this year’s freshet.

Gravel extraction from the Lower Fraser has also resumed after several years where little or no gravel was taken out. A large removal near Chilliwack was completed, stopping short of the 400,000 cubic metre target on the advice of environment monitors, Penner said.

That removal and a smaller one near the Agassiz-Rosedale bridge brought the province close to its target for relieving the accumulation brought down by each spring freshet.