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→Environmental Effects Monitoring
The scale of environmental effects monitoring may be at the stream reach, subwatershed, watershed or community scale. Sites must be carefully selected to ensure that the impact of stormwater management measures that are being assessed have the potential to have a significant impact on the receiving watercourse. In practice this means that runoff from the assessed drainage area represents at least 50% of total flow within the receiving water system (otherwise system response to land use changes and/or management measures may be difficult to detect with statistical significance).
The scale of environmental effects monitoring may be at the stream reach, subwatershed, watershed or community scale. Sites must be carefully selected to ensure that the impact of stormwater management measures that are being assessed have the potential to have a significant impact on the receiving watercourse. In practice this means that runoff from the assessed drainage area represents at least 50% of total flow within the receiving water system (otherwise system response to land use changes and/or management measures may be difficult to detect with statistical significance).
[[File:Temporal changes (5-yr median) 1966 - 2022.jpg|thumb|600px|Temporal changes in 5-year median chloride concentration (1966-2020). All stations had higher median chloride concentrations in 2016-2020 compared to the last time 5-year median concentrations were culminated into a report (2011-2015) and the difference in concentration between time periods appeared to be greater for stations with higher chloride concentrations. The reasons behind this pattern are unknown and warrant further investigation, but median concentrations are above the chronic level of 120 mg/L in all of the more urbanized watersheds, south towards Lake Ontario (TRCA, 2021).<ref name="example2">TRCA. 2021. Spatial Patterns (2016-2020) and Temporal Trends (1966-2020) in Stream Water Quality across TRCA’s Jurisdiction. Prepared by Watershed Planning and Ecosystem Science. October, 2021. https://sustainabletechnologies.ca/app/uploads/2021/10/2016-2020-SWQ-Report-v11_FINAL_AODA-FA.pdf</ref>]]
In addition to detailed assessments of receiving water health, environmental effects monitoring should also include monitoring of significant point sources of contaminants as well as major stormwater management practices treating water discharged to the area of interest. This allows for meaningful relationships to be developed between contaminants sources, management measures and environmental conditions. In addition to precipitation and air temperature, general environmental parameters that may be measured in environmental effects studies may include those listed in the table below:<br>
In addition to detailed assessments of receiving water health, environmental effects monitoring should also include monitoring of significant point sources of contaminants as well as major stormwater management practices treating water discharged to the area of interest. This allows for meaningful relationships to be developed between contaminants sources, management measures and environmental conditions. In addition to precipitation and air temperature, general environmental parameters that may be measured in environmental effects studies may include those listed in the table below:<br>
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|+'''Key parameters of interest in environmental effects monitoring studies'''
|+'''Key parameters of interest in environmental effects monitoring studies'''
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|Index of Biotic Integrity, [https://trca.ca/conservation/environmental-monitoring/technical-training/ontario-stream-assessment-protocol/ Ontario Stream Assessment Protocol (OSAP) protocols]
|Index of Biotic Integrity, [https://trca.ca/conservation/environmental-monitoring/technical-training/ontario-stream-assessment-protocol/ Ontario Stream Assessment Protocol (OSAP) protocols]
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Conservation Authorities have established networks of regional environmental monitoring stations with data extending back several decades. These data sets can be helpful to establish baseline stream health indicators for environmental effects monitoring programs and assess trends over time. An example of the data collected at these monitoring stations by [https://trca.ca/watershed-planning-reporting/ TRCA's Watershed Planning and Ecosystem Science team] can be seen in the image above depicting 5-year median concentrations of chloride found in the CA's watershed.