Healthy salmon streams are characterized by “channel complexities” such as fallen logs, overhanging vegetation, boulders and smaller gravels, riffles and pools. These all work together to provide places where salmon can rest and hide, where juveniles can feed and where adults can spawn.
Heavy stormwater flows in urban streams such as Cougar Creek tend to destroy these features and/or bury them under a load of sediment. Lower Cougar Creek in particular is subject to lots of sedimentation, because as the velocity of flow decreases in this shallow stretch, sediments drop out.
Since 2016, Streamkeepers have been using the “fishery window” (August & September) to install shallow rock dams called weirs in Cougar Creek’s most productive spawning areas near Westview Bend. In addition to creating some deeper, cooler pools in which salmon can take refuge, weirs also cause water to tumble, which in turn increases its oxygen content.
Surrey’s SHaRP (Salmon Rehabilitation Program) teams have also installed weirs in the stretch of creek between Scott and Nicholson Roads.