Toronto and Region Conservation monitors the quantity and quality of groundwater at various wells across the region.

TRCA groundwater monitoring

What Do We Monitor And Why?

The Provincial Groundwater Monitoring Network (PGMN) was established in April 2000 to assess current groundwater conditions and provide an early warning system for changes in water levels and water quality. PGMN is a partnership program between the Ontario Ministry of the Environment and Climate Change and the province’s conservation authorities, as well as some municipalities in areas not covered by a conservation authority. There are almost 400 wells monitored across the province.

The role of the Ministry in the network is to set policy direction, develop strategic objectives and maintain the Provincial Groundwater Monitoring Information System database. TRCA is responsible for maintaining the digital telemetry systems at 19 groundwater monitoring wells in our jurisdiction, collecting water level data and arranging for chemical analyses of water quality samples at dedicated wells.

Of the 19 wells that were monitored for water level data in 2015, a total of 16 groundwater wells were also sampled for water quality. TRCA also intends to expand the network through partnerships with the regional municipalities of Durham, Peel and York. The Province is currently exploring options to convert to a satellite telemetry system over the next few years.

TRCA groundwater monitoring

What Are The Data Telling Us?

Approximately three million residents in Ontario rely on groundwater from municipal and private wells as their primary source of drinking water. Many communities are dependent on groundwater supplies to maintain existing domestic, commercial, industrial, agricultural and institutional operations. Overdrawing and contamination activities are elevating the stress placed on this vital resource.

In the most recent Toronto and Region Watersheds Report Card, groundwater quality in TRCA watersheds was reported as “Good” with the best water quality found in the intermediate aquifer on the Oak Ridges Moraine. The majority of the wells also yielded “Very Good” results for nitrates and nitrites, indicating little or no contamination from agricultural manure, fertilizers or leaky septic systems.

Several wells, unfortunately, did show chloride levels above the Canadian drinking water standards in urbanized portions of the watersheds, where road salt may be a factor or in deeper aquifers over shale bedrock that have naturally elevated chloride levels.


Jeff Vandenberg, Environmental Technologist
Environmental Monitoring and Data Management