At the beginning of each month from January 2006 to June 2006 updated snow survey reports from the BC Ministry of Environment River Forecast Centre (RFC) were fed into the FWMT system. Snow reports included measurements of current snow-packs, recent climatic conditions, and forecasts of what might be expected in terms of future runoff. The Fish Water Management Tool combined this data with real-time information on fish stocks and river and lake conditions to predict the impacts of a wide range of water storage and release scenarios on both fish and other water users. The most practical scenarios were reviewed by the Operational Team who then sought consensus on the best flow release pattern.
The process of balancing water budgets was complicated by changing weather early in the season and by an early and voluminous runoff later on. In the closing months of 2005 a very low snow-pack for the basin resulted in expectations of a drought season. Flows were kept to a minimum to retain the greatest possible volume in Okanagan Lake.
The onset of the New Year brought heavy snow loads shifting the outlook from drought to flood. To keep Okanagan Lake close to target elevations, releases from Okanagan Dam had to be increased to the maximum level commensurate with safeguarding sockeye eggs from scour conditions.
As spring approached, snow-packs were closer to normal but the weather remained cool and the start of runoff was initially delayed. By the third week in May, however, a rapid runoff began. Inflows to Okanagan Lake were high as were tributary flows to Okanagan River. Releases from Penticton Dam had to be scaled back to avoid flooding around Oliver and Osoyoos Lake and this caused Okanagan Lake to rise. Towards the end of May, Okanagan Lake was approaching full pool and rising quickly. The runoff was earlier, higher and more rapid than expected but was handled without flood damage and without surpassing the target level for Okanagan Lake.
This operational year was described as a “banner year” by both water managers and fisheries scientists. The Fish Water Management Tool was used extensively and the Operational Team cooperated closely to make wise water balance decisions that benefited all interests. Flooding was avoided and the highest level of protection was provided for sockeye and kokanee populations. The year wrapped up with congratulatory notes from both the head of the Water Stewardship Division and the Chair of the Canadian Okanagan Basin Technical Working Group.