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NRBS - Home Table of Contents		Northern River Basins Study Final Report 1.0 Background 1.4 The Peace-Athabasca Delta Figure 1.4.1 Peace - Athabasca Delta The Peace-Athabasca Delta (Figure 1.4.1) is an unique environmental feature. Athabasca is Cree for "where there are reeds," describing the delta's marshes and grasslands. The flat terrain is a patchwork of marshes, lakes, mud flats, sedge meadows, willow and shrub thickets and forests of white spruce and balsam poplar, interwoven by numerous winding channels. With its variety of landforms and lush vegetation, the delta has the capacity to support a diverse mixture of animal species. In 1985, the Canadian Wildlife Service counted 220 species of birds, mammals and fish that inhabit the delta during some part of their lifecycle. Well over half of these species are birds. Twice each year, millions of birds follow established routes (or "flyways") on their north or south migrations. All of the four major flyways in North America converge on the Peace-Athabasca Delta. Many birds use the delta as a pit stop to "fuel up" for the rest of their long trek, while others stay on to nest. Among these are tundra swans; snow, white-fronted and Canada geese; Ross' goose and a variety of ducks. In 1982, the delta was recognized by the Convention on the Conservation of Wetlands of International Importance (also known as the Ramsar Convention) as an internationally significant site for waterfowl habitat. The Ramsar Convention was drafted in Ramsar, Iran in  1971 to acknowledge wetlands as areas of international biological significance. [Photo 3 on CD3: Canada geese]
NRBS - Home Table of Contents Top of Page		The characteristics of the delta that contributed to the Ramsar designation have been significantly altered. The complex water flows in the Peace-Athabasca Delta are fundamental to its environmental characteristics. Since the landscape of the delta is relatively flat, many of its waterways can flow in two directions. The direction of the flow depends upon the relative water levels in different parts of the delta. When the water level in Lake Athabasca is higher than Claire and Mamawi Lakes, water flows westward into the delta. When Lake Athabasca is low, water flows east out of the delta lakes and into Lake Athabasca. The reversing concept holds true for the channels that drain the delta: Chenal des Quatre Fourches, Revillon Coupé and Rivière des Rochers. Usually, these three channels flow north to meet with the Peace River and then continue north as the Slave River. However, when the flooding of the Peace River rises higher than the water level of Lake Athabasca, water flows south into Lake Athabasca and the delta. The backflooding of the three channels by the Peace plays an important role in maintaining the delta wetlands. Many of the small lakes of the delta exist as "perched basins" that are only replenished through the periodic, spring ice jam flooding by the Peace River. However, since the construction of the Bennett Dam, these floods have been rare and less extensive. As a result, many of the marshy areas of the delta are transforming into terrestrial landforms dominated by willows and sedges. The transformation is of concern to both ecologists and local residents. Residents of Fort Chipewyan, located on the shores of Lake Athabasca, rely on the delta for fishing, hunting and recreation. Fort Chipewyan is one of the oldest communities in Alberta. During the heyday of the fur trade, Fort  Chipewyan was an important outpost for the Hudson's Bay Company and the delta was renowned for the quantity and quality of its muskrat pelts. However, many of the marshes are now too shallow for muskrats to overwinter. Falling water levels have also decreased habitat for waterfowl and fish.
NRBS - Home Table of Contents Top of Page		During the 1970s, a considerable amount of effort went into stabilizing the water levels of the delta through the construction of control weirs along the three channels. The weirs were intended to reduce the outward flow of water while still allowing the Peace River floods to wash into the delta. The weirs proved effective in retaining water, but they could not mimic the natural fluctuations in water levels that are integral to the unique environmental characteristics of the delta. The Quatre Fourches dam was later removed because it kept waters artificially high year-round. [Photos: Left: 003 on CD1, Right 018 on CD1:] Then and Now: Egg Lake is one of the perched basins of the Peace-Athabasca Delta that is only replenished by periodic overland flooding. Its marshy shores were once a focal point for fur trappers and a haven for waterfowl. In fact, this lake once set the Hudson's Bay Company standard for high quality muskrat pelts. In the absence of these floods over the last two decades, Egg Lake is being transformed into a terrestrial ecosystem marked by grasses and willows. The photo on the left was taken roughly 20 years ago, while the one on the right was taken in 1994.]

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