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Executive Summary

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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 Lower Crossing monitoring station, located at Mile 496 on the Alaska Highway at Liard River, B.C. Water quality samples were collected between 1984 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, chromium, copper, iron, lead, manganese 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 metals were probably not bio-available and would be removed by drinking water treatment needed to remove turbidity.
· Turbidity removal and disinfection are needed prior to drinking water use.
· The river had a low sensitivity to acid inputs.
· Hardness levels were generally within the optimum range for drinking water in the summer and above the optimum range in the winter.
· 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 Lower Crossing because there are no apparent water quality trends or concerns at this time.

Figure 1 Map of Liard River (Scale 1:3,300,000)

Authors

Jang, L. Water Quality Section, Water Management Branch, Ministry

of Environment, Lands and Parks, Victoria, B.C.

Pommen, L.W. Water Quality Section, Water Management Branch, Ministry

of Environment, Lands and Parks, Victoria, B.C.

Contributors

Boettger, B. Water Quality Consultant, Environmental Health Program, Public Health Protection Branch, Ministry of Health, Victoria, B.C.

Carmichael, B. Environmental Protection, Ministry of Environment, Lands and Parks, Omineca-Peace Region, Prince George, B.C.

Holms, G.B. Water Quality Section, Water Management Branch, Ministry

of Environment, Lands and Parks, Victoria, B.C.

Regnier, R. Monitoring Strategies Division, Monitoring and Systems Branch,

Pacific and Yukon Region, Environment Canada, Vancouver, B.C.

Ryan, A. Monitoring Strategies Division, Monitoring and Systems Branch,

Pacific and Yukon Region, Environment Canada, Vancouver, B.C.

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