Groundwater our valuable but vulnerable Hidden Resource Groundwater is one of British Columbia's most valuable natural resources. Groundwater is developed through the construction of dug and drilled wells and provides important groundwater supplies for an estimated 750,000 people in British Columbia. In areas of the Province such as many of the Gulf Islands, groundwater is the sole source of domestic water supply. Most recharge to groundwater is from direct infiltration of precipitation at ground surface. On the west coast of the Province about 75 percent of the annual precipitation occurs between October and March recharging and replenishing our surficial and bedrock aquifers. However, limited groundwater storage is available during dry summer periods and many wells experience groundwater quantity and quality problems during these periods.