Groundwater in Ontario is a precious resource. Out of a total population of 11 million in Ontario, 1.2 million depend on groundwater from municipal water supplies and an additional 1.8 million use groundwater from private wells. Of the 620 municipal drinking water systems in operation in Ontario, 400 (65%) depend on groundwater for their water source. A number of recent incidents and studies suggest that these resources are increasingly being stressed.

The Province of Ontario maintained a network of monitoring wells between 1946 and 1979. Since that time, most groundwater monitoring in Ontario has been conducted as part of site specific assessments. A review by the Ministry of the Environment (MOE) in 1997 affirmed the need for a comprehensive, groundwater database for Ontario to characterize the location, quality and sustainable yield of the resource and to describe where, how and why the resource is changing.

During the spring and summer of 1999, low water conditions in many parts of southern Ontario prompted the formation of an inter-ministerial task force to assess drought conditions, determine trigger levels and develop a response strategy. One of the major recommendations of the inter-ministerial task force was to establish a provincial groundwater monitoring network. It was recommended that the network be established on a watershed basis and that a partnership be struck with appropriate stakeholders for the ongoing operation of the network. The Ministry of the Environment (MOE) determined that Conservation Authorities were the most appropriate stakeholders based on their structure, location and operations. Groundwater is an important component of the hydrologic cycle, for which, in general, there is an information gap across Ontario.



There is a need for baseline groundwater data in order:

• To carry out drought assessment and contingency planning.
• To define emerging issues (e.g. trends toward water shortages, contamination etc.).
• To meet the demands of the public and business concerns for data on groundwater supply and quality.
• To provide scientific data to support water taking and land use policy.
• To support integrated municipal planning.
• To provide broader access to groundwater data through the Water Resources Information Project.

A groundwater monitoring network will enable an accurate assessment of current groundwater conditions to be made. It will provide for an early warning system for changes in water levels (caused by climatic conditions or in response to human activities such as water takings), as well as provide for an early warning system for changes in water quality from natural or manmade causes. It will also provide information for making sound land use planning decisions.