RIVER FORECAST CENTRE

Water-Supply & Stream Flow Conditions

Commentary updated July 24, 2006

Rivers in a large portion of the province are continuing to experience low streamflow conditions for the date. In some areas, streams flows are very low. These areas include the most of the Peace River basin, along with some streams in the upper Fraser, middle Fraser, eastern Nechako, Thompson, and elsewhere. The Fraser River at Hope and the Thompson River at Spences Bridge are both currently at 20-year return period low flows.

SYNOPSIS: Winter snow water accumulation was near normal or above normal for many areas (Vancouver Island, South Coast, Okanagan, Kootenay, Columbia, South Thompson), but below normal in the middle and upper Fraser River basin, the eastern Nechako, and the north-east corner of the province. Much of that snow melted early, in mid-May, during a period of near-record high temperatues. Since then, rainfall during June and July has been below normal in most areas. For the north and central interior, rain during May and June was only about 50% of normal.

As a result of the intense mid-May heat and early snowwmelt, followed by the drier than normal June and July, most rivers throughout the of the province are currently below their long-term median flows for the date. Some rivers are currently experiencing very low flows, and are at record low flows for the date

BC INTERIOR:

Thompson Basin: All gauged rivers are currently below median flows for the date (generally in the 5-10 year return period low flow range). The Eagle River at Malakwa is currently at a record low for the date, and the Coldwater River at Merrit is approaching a record low for the date. The Thompson River at Spences Bridge is below a 20-year low flow.

Upper Fraser: All gauged rivers are currently below median flows for the date (generally near a 10-year return period low flow). .

Middle Fraser: Most rivers in the middle Fraser are near 10-20 year return period low flows. The Horsefly River is at a 20-year low flow. Cayoosh Creek near Lilloet is at a 20-year low flow. Some rivers along the western side are currently above median flow levels, reflecting glacial melt. The Fraser River at Hope is at a 20-year return period low flow.

Peace: Most gauged rivers in the Peace are currently experiencing very low flow, generally in the 10-20 year return period low flow range. The Finlay River, Halfway, Osilanka and Nation rivers are currently at record low flows for the date. Other rivers (Ospika R., Mesilinka R., Omineca R.) are below 20-year return period lows.

Okanagan: Many rivers are in the 5-10 year return period low flow range. The Tulameen and Similkameen rivers are at 20-year return period lows. Coldstream Creek and Whiteman River in the north Okanagan are slightly above median for the date, likely reflecting runoff from some rainfall in mid-July.

Kootenay/Columbia: Most gauged rivers are currently slightly below median flows for the data. The Kootenay River is near a 20-year return period low flow.

BC COAST: Most coastal rivers are currently in the 80-120% of normal range. The Tsolum River on Vancouver Island is currently recording below its previous record low for the date, however, other rivers on the east side of Vancouver Island are near long-term median levels. The Skeena River is at a 10-year return period low flow, while the Bulkley River is at a 20-year low. The Saloomt River (at Hagensborg, near Bella Coola) is currently at a record low flow for the date.

OUTLOOK: The warm and dry weather of the past week will be reflected in continuing decline in water levels, particularly in the areas of concern noted above. Without a significant and prolonged period of wet weather, rivers in these areas, along with the Fraser River mainstem (as far downstream as Mission) and the Thompson River mainstem, will continue to recede, and will remain at well below normal levels into August.

Indicators

We are currently monitoring five indicators. These are:
- Basin Snow Indices (in Snow Survey Bulletin)
- Standaridized Precipitation Indices
- Monthly Precipitation, % of Normal
- Streamflow conditions
- Groundwater conditions

During the winter & early spring, we utilize Basin Snow Indices and Standardized Precipitation Indices (SPI) as indicators of future drought conditions. Basin Snow Water Indices can be found in the Snow Survey Bulletin.