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Jeff Vandenberg

Environmental Technologist

Environmental Monitoring and Data Management

Groundwater Monitoring

Claireville Groundwater Station


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 Environment and Climate Change (OMOECC) and Conservation Authorities, including some municipalities in areas not covered by a conservation authority. There are almost 400 wells monitored across the province.

The role of OMOECC in the network is to set policy direction, develop strategic objectives and maintain the Provincial Groundwater Monitoring Information System (PGMIS) program database. The mandate of TRCA’s Regional Watershed Monitoring Program is to maintain the digital telemetry systems at 19 groundwater monitoring wells in our jurisdiction, collect water level data and arrange for chemical analysis of water quality samples at dedicated wells. Over time, TRCA intends to expand the network through partnerships with the regional municipalities of Durham, Peel and York.  

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 2013 Toronto and Region Watersheds Report Card, groundwater quality in TRCA's watersheds was reported as "Good" with the best water quality found in the intermediate aquifer on the Oak Ridges Moraine. 

TRCA Watershed Grades: Groundwater Monitoring

The majority of the wells also yield very good results for nitrates and nitrites, indicating little or no contamination from agricultural manure, fertilizers or leaky septic systems.  However, several wells 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. 

Aquifer:A water-bearing layer of rock, sand, or gravel capable of absorbing water (Merriam-Webster, 2014).

Groundwater:Water that occurs below the surface of the Earth, where it occupies spaces in soils or geologic strata. Most groundwater comes from precipitation, which gradually percolates into the Earth. Typically, 10-20% of precipitation eventually enters aquifers. Most groundwater is free of pathogenic organisms, and purification for domestic or industrial use is not necessary. Furthermore, groundwater supplies are not seriously affected by short droughts and are available in many areas that do not have dependable surface water supplies.