Driscoll Island Cold Water Refuge

Water temperatures frequently exceed salmonid preference and survival thresholds in the Okanogan and Similkameen Rivers. Throughout the Okanogan Basin significant efforts are underway to improve tributary habitat for spawning and rearing, increase in-stream flows, and improve upstream water management through negotiations with Canada and the US co-managers. Gains have been made, but high water temperatures remain one of the most significant limiting factors in the Okanogan watershed, particularly from July through September.

The recently completed Driscoll Island Cold Water Refuge project investigated the viability of ground water to create off-channel distributary refuge habitat features. The ground water investigation determined that there is viable quantities of water several degrees (Celsius) cooler than the adjacent Okanogan and Smilkameen Rivers. As a result of the ground water findings we developed engineering designs for implementing these refuge channels in phases. Once implemented these cold water off channel features would be available as refuge for salmonids during a critical time of year when water temperatures often drive juveniles to migrate to less favorable habitats.

The goal of this project is to investigate and design cold water off channel refuge for juvenile salmonids that would be available during a critical time of year when water temperatures often drive juveniles to migrate to less favorable habitats.