| Abstract/Description or Keywords |
The water quality of the Nechako River and some of its tributaries ( Figure 1) in the Takla-Nechako area was assessed by examining water quality data collected to about December 1983. This assessment was begun because of a proposal by Alcan to proceed with the Kemano Completion project. Although Alcan's proposal was subsequently postponed for an indefinite period the water quality assessment was completed so that water quality objectives would be in place. A detailed technical appendix was prepared and forms the basis for the conclusions presented here. The Nechako River is one of the major tributaries to the Fraser River which it joins at Prince George. It originates from a former chain of lakes, now known as the Nechako Reservoir ( Figure 2.), which drain an area of about 14,000 km2 west of Prince George. Before 1950, the Nechako River was formed by water draining eastwards from two sets of lakes. One set comprised Skins Lake which flowed into Cheslatta Lake then into Murray Lake and finally into the Nechako River at Cheslatta Falls. The second set originated from Knewstubb Lake as the combined flow from Ootsa, Entiako and Eutsuk Lake drainages, and after passing through the Grand Canyon of the Nechako was joined at Cheslatta Falls by water from the first set of lakes. Since 1950, the larger lakes have been used as a storage reservoir for hydroelectric power. The power is generated at Kemano aout 240 km west from Cheslatta Falls, and is transmitted to Alcan's aluminum plant at Kitimat. To form the reservoir, the Kenney Dam was completed in 1952 at what became the outlet to Knewstubb Lake. The dam eliminated previous flows into the Nechako River at this point and backed water westward via Knewstubb and Natalkuz Lakes into Ootsa Lake. Excess water not required for power generation is released from Ootsa Lake into Skins Lake via the Skins Lake Spillway. The overflow travels via Cheslatta and Murray Lakes to the Nechako River. Downstream from Cheslatta Falls the Nechako River flows in a north-easterly direction to Fort Fraser. Here it is joined by the Nautley River, a short river draining Francois Lake and Fraser lake from the west. The Nechako River then flows east past Vanderhoof and Isle Pierre into the Fraser River at Prince George. Major tributaries in this reach are the Stuart River which drain Stuart Lake from the north and the Chilako River which enters from the south near Prince George. Kemano completion was a proposed Alcan project ( Figure 2.) designed to increase hydroelectric power generated at Kemano while increasing aluminum smelting capacity at other new sites. It involved increasing the water supply to the Nechako Reservoir by diverting water from the Nanika River system which presently drains northward via the Morice River to the Bulkley River, and by decreasing the discharge to the Nechako River. It was contemplated that the flow and temperature of water entering the Nechako River would be controlled by building a dam at the outlet of Murray Lake and a cold water release structure at the Kenney Dam. This latter structure would once again allow water to flow from Knewstubb Lake into the Nechako River. |
