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 various activities including oil and gas development, mining, forestry and agriculture.

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 Fort Liard monitoring station, located at the Hudson's Bay Company Post near Fort Liard. Water quality samples were collected between 1984 and 1995 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, arsenic, cadmium, organic carbon, chromium, copper, iron, lead, manganese, selenium, and zinc at times exceeded water quality criteria for aquatic life or drinking water due to high levels of suspended sediment during high river flow. These substances were probably not biologically available and would be removed by drinking water treatment needed to remove turbidity.
· Turbidity removal and disinfection are needed prior to drinking.
· The river was often too turbid for recreation during the summer.
· The river had a low sensitivity to acid inputs.
· Hardness levels were mostly above the optimum range for drinking water, reaching the poor range during winter.
· The water was cool enough for drinking except during the summer, when it was warm enough for water-contact recreation.

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