Nanaimo's drinking water comes from melting snow and rainfall that feed two large reservoirs in the mountainous watershed of the Nanaimo River. These reservoirs impounded by the South Fork and Jump Creek dams provide an adequate water supply for both our thirsty population and year-round flow in the Nanaimo River.

Timber harvesting in Nanaimo's watershed can increase soil erosion and thereby the amount of silt and clay in our reservoirs. Silt and clay poses no direct threat, but it does reduce the effectiveness of chlorine in killing potentially harmful water-borne microorganisms. The City of Nanaimo has a comprehensive water-testing program to ensure water quality and protect public health.