Ministry of Environment
Water Supply and Streamflow Conditions Bulletin
Issued: October 2, 2012
Weather:
After a wetter than normal spring and early summer across most of British Columbia, dry conditions have prevailed since early to mid-July. Cumulative rainfall since August has been very limited across most of the province, with record dry conditions through August and September in a number of areas. Regions with particularly dry conditions include the South Coast, Vancouver Island, and Peace regions.
Streamflow Conditions:
Due to large snowpacks and heavy rain through the snow melt period this year, larger rivers and rivers draining high elevation terrain are generally flowing at near normal levels for this time of year. This includes the Kootenay, Columbia, Central Coast and most areas in the Central Interior.
In the Peace region, streamflow levels have been extremely low through most of the summer. Flows on the Kiskatinaw and Moberly Rivers are at historic low levels. The Pine River at East Pine (07FB001) is currently flowing below 5% of normal (below a 1 in 20 year flow). Inflow rivers into the Williston reservoir are also reaching low levels, with most gauged rivers flowing at 20-80% of normal levels.
Smaller rivers on the South Coast and Vancouver Island (e.g. where snow influence on the rivers are more limited) typically experience their low flows during the late-summer/early fall. Due to the limited precipitation in these regions over the summer, river levels are below normal for this time of year. This includes the Tsolum River, Tofino Creek, Koksilah River, Sarita River, and Carnation Creek; similar conditions are expected on other ungauged rivers through the region. Larger rivers on the South Coast and Vancouver Island (e.g. where there is greater influence from snowmelt and glacier input), rivers are nearer to normal levels. Normally October is the month when weather patterns shift, and coastal areas of British Columbia transitions into the fall “wet” season. It is expected that coastal rivers will recover quickly once this transition occurs. However, as described below, the current outlook is for continued dry conditions for at least the next week or more.
Over the past one to two weeks, rivers in the Okanagan and Similkameen regions have begun dropping below normal levels, with most rivers currently at 20-80% of normal for this period. In particular, the Similkameen River near Hedley (Water Survey of Canada 08NL038) is at a 1 in 5 year return period low flow, Camp Creek near Thirsk (08NM134) is near a 1 in 5 year low flow, Vaseaux Creek above Solco Creek (08NM171) is at a 1 in 5 year low flow, the Whiteman River above Boleau Creek (08NM174) is near a 1 in 10 year low flow, and the Kettle River near Ferry (08NN013) is near a 1 in 10 year low flow.
A current map of 7-day average streamflows at select Water Survey of Canada hydrometric stations across British Columbia is updated weekly on Monday and is available on the River Forecast Centre website at: http://bcrfc.env.gov.bc.ca/bulletins/watersupply/7DayPercentMedian2012.htm
Drought Level and Water Supply Conditions:
With on-going extreme dry conditions and historic low flows, areas of the East Peace Region (including the mainstem and tributaries of the Moberly, Beatton, Kiskatinaw, and Fontas) are currently at a Level 4 Drought (Extremely Dry). Level 2 Drought (Dry) conditions are present in the remainder of the Peace Region, the Middle Fraser, Nicola, South Coast and Vancouver Island. Other areas of the province remain at Drought Level 1.
Information on Drought in BC is available at: http://www.livingwatersmart.ca/drought/.
Outlook:
The seasonal shift into wetter conditions along coastal British Columbia has begun. So far this season low-pressure storm systems have been limited to Alaska and the north coast of BC.
On the shorter-term, a high-pressure ridge is forecast to build over the coming days, with continued dry conditions expected to persist into next week. Seasonal weather forecasts from Environment Canada are indicating an increased likelihood of continued drier than normal conditions for most of British Columbia through the October-November-December period.
Current weather outlooks are not favourable for improved river levels through the province. Over the next 1-2 weeks, dry conditions are expected to persist, and continued deterioration of drought conditions is expected.
For Current Warnings and Advisories please click this link .
The River Forecast Centre will continue to monitor conditions and will provide an update as conditions warrant.
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