CRT Library
Impacts of the Operation of Existing Hydroelectric Developments on Fishery Resources in British Columbia Volume 2: Inland Fisheries
This document reviews the impacts of all of British Columbia’s hydroelectric dams on fisheries. This includes treaty and non-treaty dams in the Columbia River System. For each dam there is a description and explanation of water licenses and operational constraints, electrical generation, enhancement facilities, operational regime. For both the reservoir and downstream system there is information on the: physical and chemical environment, sport fish populations and recreational fishery. Discusses the impacts of the dams on fisheries and makes recommendations for restoration in some cases. Excellent resource for fisheries information on the Columbia system.
“The report reviews the main features of 46 hydroelectric dams and diversions in B.C. and summarizes available information on the inland sport fish resources within and below the impoundments. Forty of the dams and diversions are owned and/or operated by B.C. Hydro, four by West Kootenay Power and two by Cominco. The projects are collective- ly responsible for generation of about 95 percent of the electrical power used in the province. Eight of the projects are located within the Columbia River basin, nine in the Kootenay River basin, two in the Peace River system, ten within the Fraser River basin, and nine are located within various watersheds on Vancouver Island. A further four are located on small lakes in coastal areas. The oldest plant still operating is Upper Bonnington (63MW) on the lower Kootenay River, constructed in 1908.
The most recent project is Revelstoke (1843 MW) on the Columbia River, completed in 1984. The impoundments cover a total area (at full pool) of nearly 6200 km 2 and regulate a total river length of about 591 km. Impoundments vary in size from 60 ha (Wokas Lake) to 177,870 ha (Williston Lake), mean depths range from 3 m (Wokas Lake) to 97 m (Seton Lake), annual maximum draw downs range from less than 1 m (Seton Lake) to 35 m (Downton Lake), and mean water retention periods range from less than 1 day (Waneta) to longer than 19 months (Williston Lake).
All the hydroelectric impoundments reviewed, with the possible exception of some small headponds, support sport fish populations. Rainbow trout, Dolly Varden (bull trout) and kokanee are the most common species in reservoirs, while cutthroat trout are common in Vancouver Island and some lower mainland reservoirs. Mountain whitefish are significant population components in reservoirs in the Columbia, Kootenay and upper Fraser water sheds. Lake whitefish are significant compo nents in the Peace River reservoirs. Lake trout, brook trout, burbot and white sturgeon occur locally in a few impoundments.
Angling effort and catches have been measured at various times and at various intensities for 16 of the impoundments. Mean catches per unit effort range from highs of just over 2 fish/angler/day (Elsie, Lower Campbell, Daisy lakes) to as low as 0.1 fish/angler/day (Alouette Lake). Recreational angling quality, a criterion based roughly on sport fish population abundance, lake access and aesthetic qualities, is considered good for about one-quarter (9 of 34) of impoundments for which information is available. Angling quality is considered moderate for another quarter (8 of 34) and poor for the remaining half (17 of 34). All the impoundments having good quality angling were natural lakes prior to hydroelectric development. Low population density is the dominant reason for poor angling quality. Extensive drawdowns, snags and floating debris are common impediments to recreational angling. All reservoirs developed after 1968 have been cleared of standing timber within the drawdown zones, while post-impoundment removal of debris has occurred in some.
Size and depth of reservoirs, mean water retention times and maximum annual drawdowns of less than 10 m appear to have little relationship by themselves to sport fish stock densities. Drawdowns exceeding 10 m annually and/or low water retention times in reservoirs with minimal tributary habitats are significant impediments to sport fish stock densities. Some degree of maturation takes place but is as yet poorly documented for B.C. reservoirs. Availability of spawning and rearing habitats within reservoir tributaries is the major factor sustaining viable sport fish populat ions. Competition from coarse fish species is a significant impediment to sport fisheries in mainland reservoirs, but the nature of the interaction is not consistent. All hydro electric reservoirs, with the possible exception of one (Daisy Lake), are classified as oligotrophic.
Periodic enhancement has been applied to four of 11 reservoirs with relatively high sport fish stock densities, three of seven with moderate stock densities and one of 14 with low stock densities. Stocking with hatchery-bred fingerlings is currently applied to six of eight enhanced reservoirs. Kokanee spawning channels are the major enhancements for the larger impoundments (Kootenay and Arrow lakes) and were provided as compensation measures for the impacts of development. Based on comparisons, four of the 11 enhanced reservoirs could not otherwise support high or moderate sport fish densities. Only two run-of-river reservoirs (Dinosaur and Hayward lakes) have been enhanced, both with poor results. Reservoirs and regulated rivers having good potential for improved recreational fisheries under enhancement programs include Kootenay, Whatshan, Stave, Buntzen and Jones lakes, and the Shuswap, Cheakamus and Puntledge rivers.
Because of serial development within the same river systems, half of the reviewed reservoirs and diversions (23 of 46) discharge into the headponds of other projects, the remain der regulate the discharges and hydrologic conditions within river systems used by sport fish. Although very poorly studied and documented, sport fish populations and habitats appear to be of generally low densities and qualities in regulated systems below reservoirs. Notable exceptions are regulated reaches of the Shuswap, Cheakamus and Puntledge rivers. About one- half of the projects which discharge to river systems have some form of discharge constraints as conditions to their water licences or in the form of written agreements between the utility and the Department of Fisheries and Oceans (DFO). Operational constraints currently in effect are all aimed at the protection of anadromous salmon
resources.
Although hydroelectric development has taken place in the province since near the turn of the century, compensation for impacted resources commenced only in 1954 for anadromous fisheries and in 1968 for inland fisheries. To date compensa tion has been provided for losses to inland fish eries within three systems – Duncan River (spawning channel, hatchery), Columbia River on the Arrow lakes and at Revelstoke (spawning channel, hatchery), and Peace River at Peace Canyon (pilot hatchery – now discontinued). Studies on a fisheries compensation program for Williston Lake were initiated in 1988. Evaluation of compensation programs is complicated by unavoidable consideration of unlike pre- and post-project conditions. Superficial comparisons suggest that in most cases compensation programs to date have not replaced impacted fishery resources. Recommended measures to improve sport fishery resources in and below hydroelectric impoundments include evaluation of the efficacy of ongoing compensation programs, improvements to impact assessment procedures to ensure adequate documen tation of pre- and post-project conditions, and enhancement of several systems through stock or nutrient supplementation.” (Taken from abstract)
Note: the item is not currently available in the CRTDL. For online availability, check: http://www.dfo-mpo.gc.ca/Library/124832.pdf
Author: Hirst, S.M.
Publisher: Canada. Dept. of Fisheries and Oceans
Date: 1991
Located through the Department of Fisheries and Oceans Canada
