The Regional District of Nanaimo’s Community Watershed Monitoring Network (CWMN) has completed over seven years of water quality sampling on dozens of rivers, creeks and streams in the region. Recently, a comprehensive report analyzed this dataset to uncover trends and provide recommendations.
Data on water temperature, conductivity, dissolved oxygen and turbidity is collected by trained stewardship volunteers and entered by RDN staff into the provincial EMS database. The sampling occurs once a week for 5 weeks in the low-flow period (August-September) and again in the fall-flush period (October-November).
This initiative is led by the RDN Drinking Water and Watershed Protection program, and was developed in close partnership with the BC Ministry of Environment. The objective of the CWMN is to better understand and track water quality to inform efforts to preserve, enhance and protect the health of the region’s surface water bodies. The long term goal is to identify trends in water quality to assist in regional land use planning, infrastructure, stewardship and restoration decisions.
In 2018, consulting water quality biologists Ecoscape Environmental Consultants Ltd. analyzed the 2011-2017 water quality data from the Community Watershed Monitoring Network and produced a comprehensive trend analysis that examined land use factors that were related to water quality exceedances.
Key findings from the analysis are summarized follows:
- The majority (79%) of sites with sufficient data demonstrated stable water quality that did not change over time.
- 12 out of the 34 sites with sufficient data demonstrated frequent exceedances of Provincial water quality objectives or guidelines over the 2011-2017 period.
- Seven of these 12 sites have high agricultural use in the watershed, two of the 12 have upstream stormwater outfalls, and three are not well understood.
- Watersheds that were less than 60% forest use are associated with changes in water quality.
- Watersheds with greater than 20% agricultural use are associated with higher turbidity and lower dissolved oxygen.
- Watersheds with high paved road densities are associated with increased conductivity and higher water temperatures.
The key recommendations from Ecoscape’s analysis included: improving streamside vegetation at priority locations; sampling for additional parameters to learn more about the source of water quality changes or issues; using the findings to direct targeted outreach and education on stormwater management and agricultural practices; updating mapping of land cover; and performing future trend analysis as more data becomes available. The DWWP Technical Advisory Committee will be consulted on how best to implement recommendations from this analysis into the ongoing CWMN program activities through the regular operational budget of the RDN DWWP program in the coming years.
To see the report in full please click on this link: Surface Water Quality Trend Analysis – CWMN Data 2011-2017 .
In January through March 2019, presentations will be made to Councils and the public on the specific findings in each area of our region. Stay tuned!
Questions about the report? Contact waterprotection@rdn.bc.ca
