A decision support system for improving “fish friendly” flow compliance in the regulated Okanagan Lake and River System of British Columbia

Abstract

The Okanagan Valley of British Columbia (BC) has one of the lowest per-capita water supplies in Canada. Large fluctuations in water supplies routinely induce seasonal extremes of flood and drought conditions that challenge the ability of decision makers to operate complex water management infrastructure (dams, dikes, irrigation networks, flood control channels) to satisfy competing objectives to meet human-system versus natural-system needs (e.g. protect property, irrigate land, protect aquatic biota). An audit of water management performance from 1982 to 1997 indicated frequent non-compliance of water regulation decisions with “fish friendly,” lake level and river discharge ranges specified by the 1982 Canada–BC Okanagan Basin Implementation Agreement (OBIA). Development and deployment of an environmental decision support system (EDSS) to provide real-time fish and water management tools (FWMT) to decision makers offered a potential means to improve the balance of water management decisions affecting both human and natural systems. The resultant FWMT-EDSS described here includes: a coupled set of four biophysical models of critical relationships among climate, fish and water that interact with a fifth water management rules model used to predict potential consequences of decisions for fish and other water users; a network of stations providing nearly instantaneous observations of lake elevation, river-discharge, precipitation and snowpack; a Structured Query Language (SQL) server database; an internet-accessible, graphical user interface; and a set of end users representing decision makers from government agencies, industry and local communities. FWMT provides a risk assessment framework to integrate biophysical processes, deal with multiple species and geographic locations, anticipate socioeconomic outcomes of water management decisions and increase cooperation among water users to improve fish and water management. Comparisons of observations from pre-FWMT “control” versus FWMT deployment years (n = 20 and 11, respectively) indicate significant improvements at both daily (p < 0.001) and annual (p < 0.05) time scales in compliance of water management decisions with OBIA guidelines to protect salmon during critical egg-to-fry emergence stages. These FWMT-enabled improvements were achieved without any increased damage to water system infrastructure, riparian property or agricultural production from flood or drought conditions.