| Abstract/Description or Keywords |
The health of the Lardeau River watershed was evaluated using the results of benthic invertebrate and water quality monitoring between 2009 and 2012. Monitoring was conducted at three sites, including an upstream and downstream site on the Lardeau River and a tributary site on Poplar Creek. Lardeau River Site 1: The upstream site on the Lardeau River (Lardeau 1) did not have a high probability of group membership to just one reference group in the BEAST analysis. This required a more complex than normal analysis of the benthic invertebrate community results, which involved running the CABIN model assessment with multiple reference group data and using the RIVPACS expected to observed ratios to decide on the most applicable stress ratings. Overall, the RIVPACS observed to expected ratios were low, indicating an impaired benthic invertebrate community throughout the study. The benthic invertebrate community metrics, however, did indicate improvement since 2009. In 2009, Lardeau 1 was determined to be severely stressed. The CABIN assessment and RIVPACS results were supported by several macroinvertebrate community metrics that are indicative of disturbance. In 2009 these metrics included a low percentage of ephemeroptera, plecoptera and trichoptera taxa (% EPT; taxa that are generally intolerant of pollution), a high percentage of chironomidae (taxa that are pollution tolerant), low total abundance; and low diversity. From 2010 to 2012, although comparison of macro invertebrate community to reference conditions (through the CABIN model assessment and RIVPACS analysis) indicated either severely stressed or stressed conditions, these results were not fully supported by the community metrics. The % EPT, number of EPT taxa, and total abundance all increased after 2009, indicating improved conditions. However, % chironomidae remained high. Water quality data were limited to annual non-metal data collection and did not reveal any parameters of concern. Sediment quality data were not collected in 2009 to identify the potential cause for poor health. However, chromium and nickel values were higher than the sediment quality guidelines for the protection of aquatic life in 2010, 2012, and 2013. The effect of these metals is uncertain, as the exceedances related to the lowest effect level guidelines, as opposed to effects where adverse effects on the biological community are expected to be high. Lardeau River Site 2: The CABIN model assessment results corresponded with the macroinvertebrate community metrics at the downstream Lardeau River site (Lardeau 2). Based on the macroinverterbate community, the site was determined to be in good condition (either unstressed or potentially stressed) in all years other than 2010. Indicators of stress in 2010 included very high total abundance of invertebrate organisms, and a high proportion of Chironomidae (a pollution tolerant taxa). The stressed condition did not appear to be the result of habitat alteration. Available water and sediment quality data did not indicate parameters of particular concern in 2010 at this site although, data were limited to non metal data collection (all years monitored), metals in 2009, and sediment quality data in 2011. The metals data indicated aquatic life guideline exceedances for aluminum and zinc. However, the likelihood of effect on the biological community was uncertain given that the low effect guidelines were exceeded, not the severe effect guidelines. Poplar Creek Site 1: The CABIN model assessment identified that Poplar 1 was severely stressed in 2009 and then potentially stressed or unstressed in subsequent years (2010 to 2012). The condition corresponded with several macroinvertebrate metrics, including in particular, the dominance of pollution tolerant taxa (Chironomidae) and the near absence of taxa that are often indicators of good water quality (Ephmeroptera, Plecoptera and Trichoptera). There were no habitat indices or water quality parameters evidenced to be causing the stressed conditions however, water quality was limited to non-metal data collected annually. |
