Water supply and streamflow conditions

Press release
July 24, 2009
Ministry of Environment

VICTORIA – A combination of below-normal snowpack accumulations this winter, and a dry, hot spring and summer have resulted in low streamflow conditions for rivers in the southern interior and south coast of British Columbia.

Rainfall in these areas has remained below average since April, with most rain resulting from convective storm cells, which produced localized rather than widespread rainfall. This, in combination with the prolonged hot weather and abundant sunshine, has resulted in rapid evaporation of soil water and surface water, causing river levels to recede more quickly than usual and leaving some rivers at record low flows for this time of year.

Given this outlook, Environment Minister Barry Penner urges all British Columbians to help conserve our water resources. For details on how to become a more efficient water user, visit www.livingwatersmart.ca

While there are low streamflow conditions for rivers in the southern interior and south coast, rivers in central and northern British Columbia (North Thompson, Cariboo, Upper Fraser, Peace, Skeena, Liard) had normal or above normal snowpacks at the end of the winter, and have received periods of frontal rain during June and July. Therefore, rivers in these areas are near or above their median levels and are not of concern.

Areas of low flow concern include:

South Thompson Basin

Nicola and Coldwater rivers are at or below their low flows of record (40-50 year low flows).
Chase Creek and the South Thompson, Salmon, Eagle, Seymour and Bonaparte rivers are all near 10-20 year low flows.
Similkameen River Basin

A drought for Osoyoos Lake was declared in May, based on a forecast of well below normal runoff for the Similkameen River.
Tulameen and Similkameen rivers at Princeton are near 20-30 year low flows.
Similkameen River at Hedley is near a 15-20 year low flow.
Okanagan River and Kettle River Basin

Inflows to Okanagan Lake have been well below normal for the past 12 months, and are ranked as the fifth-lowest since measurement began in 1918.
Camp, Mission, Trepanier and Vaseux creeks, are near 10-20 year low flows.
Coldstream Creek (near Vernon) and Shatford Creek (near Penticton) have higher flows, being only near two-year low flows, possibly as a result of some localized rain.
Kettle River (Westbridge, Grand Forks) is at a 10-20 year low flow.
South Coast

Chilliwack, Squamish and Coquihalla rivers, as well as the Coquitlam River above Coquitlam Lake, are all near 10-20 year low flows.
Stave and Clowhom rivers are near 20-30 year low flows.
Low relief, valley bottom rivers in the Fraser Valley appear to be experiencing significant low flow. The Nicomekl River in Surrey and Langley is currently below its record low flow for this time of year.
Vancouver Island

Tofino Creek, Harris Creek near Lake Cowichan, and Oyster River near Campbell River are near their low flow of record for the date, and near 20-30 year low flows.
Chemainus River, Browns Creek near Courtenay, and Salmon River near Sayward are near 10-20 year low flows.
Nanaimo and Englishman rivers are near two-to-four year low flows.
The Fraser River though the Lower Mainland is also below normal, near a two-to-four-year low flow for the date. This largely results from the low Thompson River flows. The Fraser River upstream of the Thompson River currently is near its normal levels.

Significant, widespread frontal rainfall is required to ease the low flow situation, but with the expected dry and hot weather in the forecast, river levels will continue to drop. There is a strong possibility that some rivers in the south interior and south coast may approach or exceed absolute lows of record in four-to six weeks. This will likely result in low water supply, lower than normal lake and reservoir levels, and reduced groundwater levels. In some areas, fish and other aquatic organisms may be affected.

Links:

http://columbiavalleynews.com/news/2009/07/24/drought-concerns-rising-in-okanagan/

http://www.env.gov.bc.ca/wsd/public_safety/drought_info/