| Abstract/Description or Keywords |
The health of three tributaries located in the upper Columbia watershed, Horse Creek, Ventego Creek and Hospital Creek, was reviewed using the results of benthic invertebrate and water quality monitoring from 2009 to 2012. This study determined that there was variability in the condition of the three tributaries over the monitoring period. o Upper Horse Creek (NAHOR02): The upstream site on Horse Creek, NAHOR02, was monitored from 2009 to 2012. Based on the CABIN model assessment of the macroinvertebrate community, the site was initially determined to be unstressed (2009-2010) and then potentially stressed (2011-2012). There were no water quality issues noted and thermal conditions were favourable for aquatic organisms. However, water quality data collected were limited. The potentially stressed rating indicates that there may be influences causing mild divergence of the composition of the benthic community compared to reference condition. The cause of the mild divergence from reference condition was uncertain and may either be the result of natural variation or anthropogenic changes to water quality or habitat. o Lower Horse Creek (NAHOR01 and NAHOR03): The downstream Horse Creek study site, NAHOR01, was monitored from 2009 to 2011. The channel, migrated in 2012, dewatering the site. It was replaced by NAHOR03 in 2012, situated approximately 125 m upstream of the original site. The data from these sites together were used to describe the condition of lower Horse Creek condition. The benthic invertebrate community at lower Horse Creek was assessed to be stressed in 2009 and then severely stressed in 2010. Benthic community health improved in 2011 and 2012 to be potentially stressed. The stressed conditions were evident as changes to key community composition metrics, which are known to be affected by disturbance. The unstable nature of the lower Horse Creek habitat is a likely contributor to the elevated stress ratings. The reason for the channel migration at NAHOR01 in 2012 was not verified, but the channel at this site would be expected to naturally change course, as it is situated on the active floodplain. Upstream anthropogenic activity including the cement plant, located immediately upstream of these sites in the floodplain is likely an additional factor contributing to the unstable channel. There were water and sediment quality concerns at the lower Horse Creek sites. Mercury concentration in the water column exceeded the water quality guideline for protection of aquatic life in 2009, coinciding with stressed conditions. Metals in the water column have not been measured since to confirm if this remains a parameter of concern. There were other parameters of potential concern when compared to the guidelines for protection of aquatic life, but elevated levels did not coincide with years assessed to have a stressed benthic community. These parameters were pH in the water column, and the concentrations of arsenic, iron, mercury and nickel in the sediment. Thermal conditions were suitable for aquatic organisms; however, monitoring should continue. o Ventego Creek Site 1 (NAVEN01): Ventego Creek CABIN monitoring from 2010 to 2012 indicated increasing benthic community stress over time. These results coincided with changes in macroinvertebrate community metrics. The percent of substrate embedded in finer material increased during this period and may have resulted in changes to the invertebrate community. The water quality data were limited to annual non-metal data collection. It is uncertain if a high pH reading measured in 2012 persisted and potentially impacted aquatic life. Sediment quality from 2010 indicated no parameters of concern. o Hospital Creek Site 1 (HOSP01): CABIN monitoring was conducted at Hospital Creek in 2009, and CABIN model assessments found that the benthic community was in potentially stressed condition. The non-metal water quality data collection, which coincided with CABIN monitoring, indicated no concerns at this site. |
