Canadian Okanagan Basin Technical Working Group and Douglas County Public Utility District
The Okanagan Fish/Water Management Tool (OKFWM) is an internet-accessible (www.ok.fwmt.net) model developed by ESSA Technologies to guide real-time water release decisions at Okanagan Lake Dam. Natural variation, scientific complexity, competing objectives, staff (knowledge) turnover, and other multi-agency communication barriers are challenges faced by water managers who must decide how to allocate limited and variable water supplies. In the case of Okanagan Lake (British Columbia), water levels are managed to provide a balance between flooding, fisheries, urban/agricultural withdrawals and other interests. Specifically designed for day-to-day water and fisheries managers, the web user interface and output reporting features of OKFWM provide an intuitive “traffic light” decision-making framework for choosing weekly water releases at Okanagan Lake dam. The OKFWM software developed by ESSA has undergone over 5 years of in-season use (2002-2008), and is now an embedded part of routine water operation decision-making by the Province and Fisheries and Oceans Canada.
OKFWM has been recognized as a cutting-edge and innovative computer model that allows all levels of government to participate and agree on trade-offs to best meet socio-economic and environmental goals associated with water management at Okanagan Lake Dam. Jim Mattison, Assistant Deputy Minister of the Water Stewardship Division noted, “The tool has really helped, not only improving our operation of the [Okanagan] River, but also greatly improving stakeholder and public understanding of the decisions that we make.” In recognition of this achievement, the team and the tool received a 2007/2008 Premier’s Innovation and Excellence Award, and as part of the Okanagan Basin Technical Working Group (OBTWG) they received the 2012 Murray A. Newman award for aquatic conservation.
Using the same external monthly inflow forecasts provided to the Okanagan basin water managers by the provincial Government’s River Forecast Centre, water release decisions are passed to OKFWM’s five state-of-the-science biophysical models (hydrology, socioeconomic water management rules, water temperature, kokanee and sockeye) that address lake and down-river considerations at a variety of sites. These submodels leverage web service automation for daily real-time updates on lake elevations, water temperatures and discharge in addition to manual information updates obtained from historical and ongoing field monitoring programs. This real-time information feeds into the hydrology and water temperature components of the model to “self-correct” inflow forecasts and adjust forecasts for accumulated thermal units (ATUs) which determine the windows of vulnerability for developing sockeye and kokanee eggs.
OKFWM operates in two modes: a) retrospective (or training) mode using historical data sets; and b) a prospective in-season management mode using real-time data to assist weekly water release decisions. In 2004, a comprehensive 25 year retrospective analysis was performed for the 1974 to 2003 period that included training of “apprentice” fish/water managers supported by senior managers. Results showed average sockeye smolt production gains from Osoyoos Lake of 384,000 — a 55% improvement — without adversely impacting flooding and economic interests. The system has also been used to evaluate climate change impacts and adaptation potential. In 2007, we assembled a basin-wide water budget for the 2050s period and ran these net Okanagan Lake inflows through the established operating rules embedded within the Okanagan Fish/Water Management Tool. Our study found that average egg-to-yearling survival for endangered Okanagan River sockeye may fall by as much as 44%. Additionally, our 2050 period fish/water managers were unable to achieve the current September 30 operating benchmark for Okanagan Lake even once in 28 simulated years. Consequences of extensive lake draw-downs would be catastrophic, highlighting the need for more serious preparations and quantitative water budget assessments.