The Water Quality Index (WQI), developed by the Canadian Council of Ministers of Environment (CCME) is used to assess the water quality of Pukaskwa’s rivers and streams. Three key stressors (acidification, eutrophication and metal loading) are assessed using nine parameters [pH, aluminum, calcium, total nitrogen, total phosphorus, dissolved oxygen concentration, iron (Fe), cadmium (Cd) and lead (Pb)]. Water samples are collected three times a year (spring, summer and fall) from each sampling site (White River, Willow River, Oiseau Creek, White Gravel River, North Swallow River, Swallow, Cascade River, Tagouche Creek and Imogene Creek). Samples are sent to the National Laboratory for Environmental Testing (NLET), Burlington, ON, to test for metals and to Natural Resources Canada, Sault Ste. Marie, ON, to test for nutrients. All of the other measurements are obtained using the YSI 600 QS.