Excerpt from Mackenzie River Basin: State of the Aquatic Ecosystem Report 2003 by the Mackenzie River Basin Board (p. 85-114). Full report available at


The Peace sub-basin covers an area of 323,000 square kilometers in British Columbia and Alberta. This basin contains a diversity of ecosystems: mountains, foothills, parkland, boreal forest, and wetlands. In 2001, approximately 195,000 people lived in the Peace sub-basin. The largest community is Grande Prairie in Alberta, and the second and third largest are Fort St John and Dawson Creek in British Columbia. About 12% of the population are aboriginal, representing nineteen different First Nations and the Metis Nation. A large portion of the basin is included in the Treaty 8 lands, but treaties are not yet established in some areas of the basin in British Columbia. Several First Nations claim that areas near the Williston Lake Reservoir are within their traditional territories.

The Peace sub-basin is rich in non-renewable resources (oil and gas, and coal). The boreal forest supports large-scale forestry operations; agricultural land makes up 23% of all the land; commercial fishing and trapping also occur.

Two major power-generating stations are found in the upper Peace River: the GM Shrum Station is located at the WC Bennett Dam that created Williston Lake in the 1960s, and the Peace Canyon Generating Station 23 km downstream.

Based on information collected before 1995, First Nations people living within the Peace sub-basin have raised concerns about increases in turbidity, algal growth, and pollution. They recognize that effluents from pulp mills and other sources have contributed to the pollution of the rivers. Water in some areas is no longer considered healthy to drink. In view of recent upgrades by pulp mills which have resulted in reductions in the release of several pollutants into the Peace River system, there is a need to upgrade the documentation of traditional knowledge on this topic.

Pulp mill effluents discharged into rivers of the Peace sub-basin contain significant amounts of organic matter which can be measured by assessing biochemical oxygen demand (BOD). As a result of stringent government regulations and technological upgrades by the mills, the total load of organic matter entering rivers has decreased substantially during the past decade.

The concentration of absorbable organic halides (AOX) in rivers of the Peace sub-basin declined between 1991 and 2001. The decline was greatest during the early 1990s. In the Smoky and Peace rivers, AOX are produced primarily by bleached kraft pulp mills. The decline in the AOX concentration is likely due to the decline in the AOX loading from pulp mill effluents.

The Alberta Water Quality Index has rated water quality as good at two sites in the Alberta portion of the Peace sub-basin since 1996. This contrasts with the evaluation of water quality based on traditional knowledge. Reasons for this discrepancy need to be determined. The Canadian Water Quality Index has rated water quality in the British Columbia portion of the Peace sub-basin as ‘poor’ to ‘fair’ since the 1980s. The different ratings obtained by using the Alberta and Canadian water quality indices are due to methodological differences in the way the indices are calculated. They do not indicate the water quality differs between the British Columbia and Alberta portions of the sub-basin.

First Nations people living in the Peace sub-basin noticed a significant decrease in water levels in the Peace River itself and in inland lakes up until 1994. Some small lakes had disappeared entirely. Flooding occurred less frequently than in the past. As a result, the ecosystem of the Peace-Athabasca Delta was greatly affected. It would be valuable to document current traditional knowledge and observations made since the flooding that occurred in 1996.

Construction and operation of the WC Bennett hydroelectric dam, together with climate variability, have altered patterns of water flowing in the Peace River. Although the average annual flow has not been affected since the Williston Lake Reservoir was filled, there continue to be significant effects on seasonal fluctuations and peak flows. Consequently, the river ecosystem downstream from the dam has changed. A long interval from 1975 to 1996 passed without the occurrence of a major ice-jam flood in the lower Peace River. During that period, the Peace-Athabasca Delta experienced significant drying and traditional use of some aquatic resources was disrupted. There is concern that climate change and flow regulation from the dam may lead to longer dry periods in the Delta.

In general, the Smoky River has had relatively low spring flows during the past few decades. This is related to low amounts of winter precipitation, which may be due to global climate change or natural long-term climate cycles. Efforts must be made to better understand the impacts of climate change on aquatic ecosystems.

The BC Hydro and Power Authority is the largest water user in the Peace sub-basin. Operation of the WAC Bennett Dam has altered flow on the Peace River, which has the potential to interfere with other water uses. To deal with this issue, the flows downstream of the generating stations are managed to ensure that adequate water is available to other users downstream. The amount of water allocated to users other than the BC Hydro and Power Authority is a small percentage of the total flow of the Peace River. The Peace River Water Use Plan, will balance the needs of water users along the Peace River in British Columbia, in an environmentally sustainable manner.

Commercial fishing occurs in the Utikuma Lake and at other sites in the Alberta portion of the Peace sub-basin. The current management challenge is to ensure that adequate stocks are available for the subsistence and sport fisheries and that fish populations are not adversely affected by harvest. The provincial government is working to meet this challenge by periodically adjusting quotas to balance the demands of other users against those of commercial fishers, and by reducing the number of commercial operators and the number of nets. There is a need to collect detailed information on the population status of species that have been identified by traditional knowledge as being scarce.

First nations people along the Peace River and near the Peace-Athabasca Delta noticed declines in the population of certain fish species, waterfowl, and muskrat. In the case of waterfowl and muskrat, these changes were attributed to deterioration of habitat caused by a lack of flooding in the delta. They also reported increases in beaver populations.

There are fifteen aquatic and riparian-dependent wildlife species considered to be at risk. Populations of some species are naturally rare, while populations of other species are threatened by a variety of factors including habitat loss and excessive harvesting. New legislation at the provincial and federal levels will enhance protection of these species.

There are fish consumption advisories for the Williston Lake Reservoir, Muskwa Lake, and rivers near a bleached kraft pulp mill on the Wapiti River, a tributary of the Smoky River, because of unacceptably high levels of mercury, dioxins and furans in some fish species. These fish consumption advisories are meant to protect people from consuming harmful levels of environmental contaminants. In November 2000, the consumption advisor on the Smoky River and its tributaries was eased in response to reductions in concentrations of dioxins and furans in fish attributable to substantial decreases in concentrations of these contaminants in pulp mill effluent.

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