SOURCE WATER PROTECTION

the fatal contamination of municipal water wells in Walkerton, Ontario the provincial government plans to protect source water in all watersheds (Fig. 1). The priority is to control land use and to engineer current well-head and stream/lake intake areas using a multi-barrier approach under the precautionary principle. A Technical Experts Committee (TEC, 2004) identified several guiding principles for carrying out source water protection (SWP): • adopt a watershed-based approach (while addressing extra-watershed implications) • develop free and open data / information sharing • apply sound science as the basis for risk assessment • assess uncertainty • continue to renew and improve watershed plans • commit to ongoing research in support of source protection plans (applied research and sharing of ‘lessons learned’) Figure 1. Watershed or proposed jurisdictional boundaries for planned implementation of source water protection in Ontario (base map from Ontario Ministry of Natural Resources, moraines modified from Barnett et al., 1991) Of fundamental importance from a geoscience point of view is: how can one protect source water? In considering groundwater and linked surface water resources, a key issue in watershed protection is the recognition and evaluation of sensitive hydrogeological terrains such as recharge areas, preferential pathways and discharge areas. To adequately assess flow systems from ‘source to tap ’ requires a geological framework developed using a basin analysis principle