The Kawartha Lakes, Otonabee River, Indian River and Ouse Rivers are the most recognizable surface features in the geographical jurisdiction of Otonabee Conservation, but an important part of the region’s huge water resources is hidden from view. Groundwater, the water stored beneath the ground surface, constitutes an immense unseen reservoir.

It is sometimes thought that groundwater flows through underground rivers or that it collects in underground lakes. Groundwater is not, however, confined to only a few channels or depressions in the same way that surface water is concentrated in lakes, rivers, streams, creeks and wetlands found throughout the region. Instead, groundwater exists almost everywhere underground. It is found underground in the spaces between particles of rock and soil, or in the crevices and cracks in rock.

Many terms are used to describe the nature and extent of the groundwater resource. The level below which all the pore spaces are filled with water is called the water table. Above the water table lies the unsaturated zone. Here the pore spaces in the rock and soil contain both air and water. Water in this zone is called soil moisture. The entire region below the water table is called the saturated zone, and water in this saturated zone is called groundwater.

Although groundwater exists everywhere under the ground, some parts of the saturated zone contain more water than others. An aquifer is an underground formation of permeable rock or loose material which can produce useful quantities of water when tapped by a well. Aquifers come in all sizes and their origin and composition is varied.

While the majority of area residents, including those living in the City of Peterborough and Lakefield, obtain their drinking water supplies from surface water sources, most individual farms and rural homes depend on water obtained from small aquifers such as thin sand and gravel deposits of glacial or other origin. Although these aquifers are individually not very significant, in total they make up a very important groundwater resource.

Protecting Groundwater

Provincial Groundwater Monitoring Network

To address a twenty year gap in monitoring Ontario’s groundwater resources, the Ontario Ministry of Environment (MOE) installed a substantial groundwater monitoring program under the Provincial Groundwater Monitoring Network (PGMN). To build a network of water monitoring stations across the province, the MOE partnered with Ontario’s 36 Conservation Authorities (CAs) because of the CA’s unique structure, location and operations. In the geographical jurisdiction of Otonabee Conservation, there are a total of 10 PGMN wells. At each of these locations, information on both groundwater level and groundwater chemistry is collected, which is then used to help set baseline conditions and assess how groundwater is affected by land use and water use.