Pauzé says she started noticing changes in her well water when a nearby quarry, now operated by the Dufferin Aggregates division of CRH Canada, started drawing millions of litres of groundwater most days to wash gravel in 2009. The quarry is located on the northern edge of French's Hill, a groundwater recharge area where rainfall enters the ground and replenishes the regional water flow system. Owners of at least a dozen wells situated downgradient of the Teedon Pit and its aggregate washing operations have complained of changes in their water, and they suspect wash water is leaking into the underlying groundwater flow system.