The Fraser River is the longest river within British Columbia. It drains about one-quarter of the province’s water and ranges from central British Columbia, to Southwest British Columbia and east to the Rocky Mountains near Jasper. The Fraser River’s headwaters are just northwest of Fraser pass in British Columbia’s Rockies and its major tributaries are the Nechako, Thompson, and Harrison rivers.

The Water Quality Index of the Fraser River at Nechako River is ranked as Good or Excellent, where as the Thompson River is ranked as Fair.

What is Water Quality Index?

The Water Quality Index is a freshwater quality indicator that is certified by the Canadian Council of Ministers of the Environment (CCME) and is developed to attain the environmental quality that is necessary to preserve our natural ecosystem. The index indicates how close we are to preserving and protecting water bodies and the aquatic life within them. Water quality monitoring data is gathered by water quality monitoring stations set up at different sites all along the Fraser River. The Index then compares the data to site-specific water quality guidelines for the protection of aquatic life. These guidelines are values that define the water conditions which if exceeded would negatively affect the aquatic life.

There are many physical and chemical characteristics of water quality that are measured at the monitoring sites, such as streamflow, major ions, trace elements, nutrients, pH, alkalinity, temperature, turbidity and dissolved oxygen. Biological change over time can alter the water quality of a waterbody, but most of the changes are due to the pollution caused by many anthropogenic factors.

These are the main sources of human-induced water pollution:

• Logging
• Mining
• Agriculture
• Dams
• Urban development, wastewater, and septic system effluent
• Industrial plants, pulp mills, and smelters

After accessing all of the site-specific conditions and how well-protected the aquatic life is, the Index ranks waterbodies in the categories of Excellent, Good, Fair, Marginal, or Poor.

The assessment of the water quality of Fraser River is stated as such:

• Fraser River at Red Pass: Good to Excellent
• Fraser River at Hansard: Good
• Nechako River: Good
• Fraser River at Marguerite: Fair
• Salmon River at Salmon Arm: Poor to Marginal
• Thompson River: Fair
• Fraser River at Hope: Good
• Sumas River at the International Boundary: Fair

Water quality is measured periodically at the monitoring stations to see the trends caused by the different variables. If these trends are negatively affecting the aquatic life, appropriate actions are taken to improve the water quality of the site and of Fraser River as whole.