Conference Agenda

Lake Ontario is the primary source of drinking water for approximately half the population of Ontario, with the majority of that population residing in the Greater Toronto Area (GTA). In 2013, Source Water Protection studies identified sensitive areas near the drinking water intakes where the risk of impacts from accidental spills is considered a credible threat to human health and safety. A spill causing an acute contamination event at one of the water supply intakes could have catastrophic impacts to the population. However, the ability of stakeholders to assess the potential impacts and develop an appropriate response is presently limited to static planning level studies and maps. These proved to be useful tools for identifying the potential locations where pollutants may show up, but they did not provide any indication of the potential risks due to the conditions in the lake at the time of the spill.

In 2019, the Ontario Clean Water Agency together with the City of Toronto, Region of Peel and Region of Durham hired DHI to develop the Lake Ontario Water Quality Forecasting System (LOWQFS). The LOWQFS assists in evaluating the likelihood of a pollution event originating from any discharge source within, and adjacent to, Lake Ontario being transported to any one of the water treatment plant intakes located along the Greater Toronto Area (GTA) waterfront. The system collects climate forecasts and uses it to update a 3D hydrodynamic model of Lake Ontario to predict the water level, currents and temperature throughout the lake. The system also includes a Spill Forecasting tool for on-demand creation of spill events that are run using the latest hydrodynamic forecast. The results are made available for plotting of spill concentrations on a map and in time-series plots, and impacted water intakes are identified and reported to relevant stakeholders.

The system is currently in operation and emergency response plans are being updated to integrate the use of the LOWQFS into the protocols and workflows.

Environmental DNA (eDNA) refers to DNA shed by organisms into the environment, and can be captured in water, soil or air samples. By identifying DNA captured in a sample, we can infer species present within a given environment. As such, eDNA is a promising tool for understanding spatial and temporal variation in biodiversity across a watershed. Clean Water Services (CWS) is a water resource and recovery district serving Washington County, Oregon. CWS discharges to the Tualatin River, a meandering, valley-floor river, sensitive to nutrient inputs and stream flow augmentation. Accordingly, our watershed-based NPDES permit directs CWS to monitor the biological characteristics of 15 sites within the watershed each permit cycle. This work is typically completed using macroinvertebrate surveys, which are costly and limited in biological scope, and therefore provide limited information. Given eDNA’s promise as a means for characterizing broader biodiversity between sites, we are piloting eDNA as a novel method for gaining detailed biological information, that could potentially be used in the future in-place of traditional macroinvertebrate surveys. The first phase of a multistep project has been to monitor nine sites representing diverse habitats within the Tualatin River Watershed, on a monthly or quarterly basis through a metabarcoding eDNA approach using water and sediment samples. This presentation will discuss the observed differences in biodiversity between sites over the course of a year, and whether eDNA metabarcoding data can be used to assess temporal shifts in species-use at a particular site or habitat area. Additionally, we will demonstrate how aquatic algae identification via eDNA compares to morphological identification via microscopy, and suggest how this comparison may inform future studies. Finally, we will discuss how we plan to use these data to develop a framework for regularly monitoring biological characteristics to demonstrate the effectiveness of our watershed enhancement actions and in fulfillment of our NPDES permit.