By Lisa Nordin
Since 2006, BC’s Forest and Range Evaluation Program (FREP) has sampled over 11,000 post-harvest sites to assesses the effectiveness of forest and range practices in conserving resource values, including riparian/streams and water quality. To date, the focus has been on random sampling at recently harvested cutblocks. Riparian/stream conditions are evaluated at a reach scale and results are typically summarized by natural resource district.
In 2019, a pilot project was completed in the Kootenay-Boundary region to develop and test a methodology for evaluating riparian/stream condition at a watershed scale using targeted sampling. This project was initiated in response to interest among decision makers in having information on factors influencing the condition of specific watersheds of concern. Using this methodology, FREP researchers combined reach-scale ground assessments in a pour-point sample design with GIS estimates of riparian disturbance to result in an integrated ranking of condition. Results were supplemented with data from assessments of potential sediment delivery and habitat connectivity at road crossings. Treatment and reference watersheds within the Kettle River and Kootenay Lake drainage areas were sampled, where the majority of land disturbances in the treatment watersheds were due to logging and roads, and the reference watersheds were mainly undisturbed by human development.
In the Kettle River drainage, the Boundary and Rock Creek treatment watersheds were found to be not properly functioning. The level of impairment was significantly higher in these two watersheds compared to all the others in the study, mainly due to a high amount of human-caused riparian disturbance. The reduced buffering capacity and resilience that results from an impaired riparian area means that these systems are presently in a sensitive state and may be easily affected and slow to recover from additional disturbance. Supplementary information gathered at road crossings indicates that sedimentation, livestock, and habitat connectivity for fish are also issues in the Boundary and Rock Creek watersheds. Attributes associated only with the stream channel identified flooding as one of the main causes of impacts in both treatment and reference watersheds in the Kettle River drainage, indicating that this area may be susceptible to naturally occurring high flow events.
In the Kootenay Lake drainage area, the Redfish treatment watershed was assessed to be in properly functioning condition, with results similar to several of the reference watersheds. Where indicators were impaired in Redfish, they were linked to road-related issues such as surface erosion and mass wasting using the riparian/stream evaluation. Similar issues were also observed at three road-crossing assessments in Redfish using the water quality assessment.
In addition to discussing the approach and findings, the report also presents recommendations for mitigating future detrimental effects in these watersheds.
WATERSHED ASSESSMENTS IN THE KOOTENAY-BOUNDARY REGION: Combining GIS and Ground-Based Methodology with Pour-Point Design (2020).pdf
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