The Kettle and West Kettle rivers experienced seasonally high water temperatures and extreme low summer flows (yet again) in 2007. Fish populations were exposed to prolonged sub-lethal and lethal temperatures exceeding 24°C during portions of the summer. These temperature effects were exacerbated by extremely low flows on both rivers. Mean monthly flows on the Kettle River, starting in July, were well below the median value going back to 1929. These cumulative impacts pose detrimental impacts to fish populations in the Kettle River as evidenced by a fish kill on the lower portion of the river in 2006.
The 2007 adult surveys on four key index sites on the Kettle River indicate that adult and sub-adult numbers increased in 2007 compared to 2006 and 2005. It was estimated that the Kettle River mainstem was supporting a mean of 48 trout per km in 2007, a slight increase from an estimated 45 per km in 2006. Furthermore, catchable (> 20 cm) rainbow trout numbers have increased in catch and release portions of the river over the last three years while they appear to have remained constant in catch and harvest sections. Similarly, the 2007 West Kettle River adult survey indicated a substantial increase in abundance of rainbow trout in stream sections with LWD restoration (treatment) compared to section without (control), continuing an upward trend since 2004 (594 trout/km in 2007 from 384 trout/km in 2006). In contrast, the control sections observed a slight decrease in 2007 (57 trout per km) compared to 2006 (77 trout per km).
In September 2007, a total, 8 LWD structures were constructed on the John Bick (private landowner) property. This work is anticipated to provide an increase in over wintering habitat and critical summer low flow pool refugia for rearing juvenile and adult fish. Some on-site modifications were necessary, but all structures conformed to regulatory approval by Department of Fisheries and Oceans (Fisheries Act), BC Ministry of Environment (Fisheries Act, Water Act), and Coast Guard (Navigable Waters Act). Future status of rainbow trout stocks within the Kettle and West Kettle rivers will hinge on mitigating impacts of high seasonal temperatures and low quality and quantity of habitat.