Executive Summary

The Liard River is a major tributary of the Mackenzie River, flowing southeast from the Yukon into British Columbia, looping through northern B.C., and then flowing northeast into the Northwest Territories to the Mackenzie (Figure 1). Water quality is affected by mining and forestry.

There are three water quality stations on the Liard River: Upper Crossing near the Yukon-B.C. border, Lower Crossing at Liard River, B.C., and at Fort Liard in the Northwest Territories (Figure 1). This report assesses water quality data collected at the Upper Crossing monitoring station located at the Alaska Highway bridge near the Yukon-B.C. border. Water quality samples were collected between 1983 and 1994 by Environment Canada. Flow was measured at a Water Survey of Canada flow gauge at the water quality monitoring station.

We concluded that:

· There were no environmentally significant trends in water quality that could be identified through visual examination of the data.
· Total aluminum, cadmium, iron, manganese and zinc at times exceeded water quality criteria for drinking water or aquatic life due to high levels of suspended sediment during high river flow. These metals were probably not bio-available and would be removed by drinking water treatment needed to remove turbidity.
· Turbidity and disinfection are needed prior to drinking water use.
· The river had a low sensitivity to acid inputs.
· Hardness levels were at or below the optimum range for drinking water in the summer, but above the optimum range in the winter months, reaching the poor range for short periods.
· The water was cool enough to be aesthetically pleasing for drinking, but too cold for water-contact recreation.

We recommend that monitoring be terminated for the Liard River at Upper Crossing because there are no apparent water quality trends or concerns at this time.