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CLOCA Released Report - Ecologically Significant Groundwater Recharge Area Delineation in the Central Lake Ontario Conservation Authority Area

Source water is untreated water from streams, lakes, or underground aquifers that people use to supply private wells and public drinking water systems. Source water protection is about protecting both the quality and the quantity of these water sources, now and into the future.

Source water protection is the first of five barriers to protect drinking water and human health. This multi-barrier approach to prevent contamination of sources of our water also includes using adequate water treatment and distribution systems, water testing and the training of water managers and staff. While it is important to ensure we have safe water treatment and distributions systems, it is more effective and cost efficient if we take the first steps to care for our lakes, rivers, and streams and preventing their initial contamination.


Watershed The best way to protect sources of water is on a watershed basis because water flows across traditional boundaries such as towns and cities. Conservation Authorities are the only watershed management agencies in Ontario that are organized on a watershed basis.

The CTC is a source protection region as described in O. Reg. 284/07 under the Clean Water Act. The region is made up of three source protection areas: Credit Valley, Toronto and Region, and Central Lake Ontario.

Credit Valley Conservation, Toronto and Region Conservation, and Central Lake Ontario Conservation Authority have been working together on drinking water source protection (DWSP) activities under memoranda of agreement since 2004 when draft legislation for source protection planning first appeared. Under the regulations of the Clean Water Act the three

conservation authorities now become source protection authorities and will continue to work collaboratively on Drinking Water Source Protection.

CTC Source Protection Region

Ecologically Significant Groundwater Recharge Area Delineation in the
Central Lake Ontario Conservation Authority Area

Download Study - (Word Doc. 26mb)

(As part of the Drinking Water Source Water Protection Program (SWP) established by the Clean Water Act, 2006, Source Protection Regions completed water budget assessments and delineated “significant groundwater recharge areas” (SGRA).  SGRAs (also referred to as “high volume recharge areas”) are defined under SWP simply as areas where groundwater recharge is greater than 1.15 times the average rate of recharge.

While identifying high volume recharge areas is important, recharge volume alone does not imply ecological significance.  To identify ecologically significant groundwater recharge areas (ESGRAs), a linkage must be established between the recharge area and the ecological features such as a cold water stream, provincially-significant wetland (PSW), or an area of natural or scientific interest (ANSI).  Establishing this linkage requires an understanding of the local hydrogeology and the factors affecting groundwater/surface water interaction.  More importantly, it requires a methodology, typically based on the use of a numerical model, to trace the movement of water from the ecological features back to the point of recharge.

This linkage was not established under the Source Water Protection initiative but is important to the Conservation Authorities mandate and to the development plan review process. CLOCA recently completed the scientific analyses to delineate the recharge areas important to ecological features utilizing CLOCA’s existing modelling tools and particle tracking analyses in this report.

This work along with supportive mapping represents CLOCA’s commitment to science based decision making and is expected to assist with the municipal development plan process and the administration of Ontario Regulation 42/06 with respect to the protection of groundwater fed features. Policies for the maintenance of infiltration will be especially important in these mapped areas.





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