Drop in Similkameen eases flood concerns

By on May 21, 2014

A drop in the volume of water on the Similkameen River in the last two days could be good news for those concerned about flooding this season.

Discharge measured near Nighthawk rose to 17,700 cubic feet per second at midnight Saturday, but has since fallen to 14,100 cubic feet per second by Tuesday morning.

The volume of water on the Similkameen River has a direct impact on the water level on Osoyoos Lake. When water backs up at the Zosel Dam in Oroville, WA, it prevents the Okanogan River from draining the lake.

After rising sharply on Sunday, the lake level has continued to rise more slowly reaching 912.90 feet Tuesday morning.

On Thursday, May 15, the B.C. River Forecast Centre issued a High Streamflow Advisory affecting the South Okanagan.

It warned that with warmer temperatures and rapidly melting snowpack, river levels were expected to rise rapidly.

Minor flooding in low-lying areas is also possible.

In an assessment released May 8, the River Forecast Centre warned that a delayed melt in April has caused snow basin indexes to be substantially higher in the Similkameen and Okanagan than is normal at this time of year.

The Similkameen was at 172 per cent of normal and the Okanagan was at 128 per cent of normal.

“The combination of snowmelt and rainfall may cause localized issues, particularly for smaller river systems and in areas which receive the heaviest precipitation,” last week’s advisory said.

Flows on the Similkameen River are expected to approach or exceed the mean annual peak flow level, the advisory added.

Thursday’s advisory also covers rivers of the Thompson Region as well as the Boundary, which includes the West Kettle and Kettle Rivers.

RICHARD McGUIRE

Osoyoos Times

 

 

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