Mega- dam expected to flip fish diversity upside down
Impact would be large, negative and irreversible, panel reports
The impact of BC Hydro’s $ 7.9- billion, 1,100- megawatt Site C dam and reservoir on the Peace River is so wide reaching it is predicted to turn fish diversity upside down, impact stream temperatures and ice flows and change the local climate to the point of increasing the risk of traffic accidents.
A Joint Review Panel report on the megaproject for the provincial and federal governments observes that:
• Three populations of fish — Moberly River Arctic grayling, mountain whitefish, and Halfway River bull trout — may be wiped out, while species such as lake trout and introduced Kokanee may flourish.
• The reservoir would influence water temperatures and the movement of ice up to 550 kilometres downstream. Water drawn from the deep reservoir would be warmer than normal downstream in winter, colder than normal in summer.
• The project would alter the local climate, generating enough fog to pose a hazard to motorists in the area. One model predicted a potential annual increase of eight hours of normal fog and 118 hours of heavy fog at the Taylor Bridge over the Peace River on Highway 37. Aviation would not be significantly affected.
• BC Hydro has proposed to monitor fog during construction and over the first four years of operation, and to install enhanced lighting in the area and changeable message boards.
BC Hydro says the change from a river- to lake- ecosystem would result in almost twice the amount of fish, with species such as kokanee, lake whitefish, lake trout, burbot, peamouth and rainbow trout best able to adapt.
Problem is, the overall fish density would actually be reduced in a water body of that size — 83 kilometres long by two to three kilometres wide — making them more difficult to catch, a concern especially for First Nations.
Overall, the dam would have “significant adverse cumulative effects on fish,” much of which cannot be mitigated through measures such as habitat compensation, the panel finds. The negative impacts on fish “would be probable, negative, large, irreversible and permanent so long as the project is in place,” it added.
BC Hydro reports 32 fish species in the Peace River at Site C, several of which are considered at risk, including bull trout, spottail shiner, goldeye, and pearl dace.
Flooding for the dam would result in the direct loss of 2,800 hectares of main channel fish habitat and 163 hectares of tributary fish habitat.
The dam and generating station would create a complete blockage to upstream fish movement. Sediments stirred up in construction of the dam could all wreak havoc on fish.
The federal fisheries department concluded the reservoir “would be a very unproductive ... low nutrient system” but concurred with BC Hydro’s predictions of fish abundance and its overall finding that the larger volume of water in the reservoir would likely result in a higher overall biomass.
BC Hydro intends to create a fisheries and aquatic habitat management plan that would include fish salvage and relocation, and an environmental monitoring program during construction to reduce sediment problems and fish strandings.
Senior government officials have six months to make their decisions on the panel report’s 50 recommendations.