BC Hydro’s application to build a dam at Site C on the Peace River has raised questions about two existing dams and the environmental impacts all three could have on a globally important ecosystem in northern Alberta.

While BC Hydro wants to focus on the impacts of Site C in British Columbia, opponents are looking 1,200 kilometres downstream – to Wood Buffalo National Park, a UNESCO World Heritage site where whooping cranes nest and wood bison roam.

Located largely within the park is the Peace-Athabasca Delta, a rich marshy area that’s designated under the Ramsar Convention as a wetland of international importance. Submissions to a joint federal-provincial review panel by three native bands and Parks Canada say that delta is already under threat because of river flow changes caused by the existing W.A.C. Bennett and Peace Canyon dams.

They argue that while Site C might bring about relatively small changes compared to the existing dams, the cumulative effect could push the Peace-Athabasca Delta toward collapse. The delta, which is a staging area for more than one million waterfowl annually, needs spring flooding events to “recharge” the wetlands. The dams reduce flooding and prevent the formation of ice jams that cause water to back up into the delta.

In a submission for the Athabasca Chipewyan, Dene Tha’ and Mikisew Cree First Nations, consultant Martin Carver argues that while BC Hydro’s environmental impact statement presents Site C as a stand-alone project, it should not be looked at in isolation.

He says environmental stresses are already building to unacceptable levels because of the hydrological changes brought about by the W.A.C. Bennett and Peace Canyon dams, which were built in 1967 and 1980, before federal environmental assessment guidelines were in place.

Dr. Carver says those dams have dramatically altered the natural flow of the Peace River, so that it now has high water in the winter, which would normally be a period of low water. Spring freshets have also been smoothed out. The result, he maintains, is that thousands of ponds scattered over the Peace-Athabasca Delta (PAD) are on the verge of drying up.

“Site C can only deepen the impacts that have been caused by the two dams already existing on the Peace River,” writes Dr. Carver. “Once a pristine resilient system, the PAD is now a vulnerable system due to prolonged and rising negative pressure on the recharge of its wetlands and lakes.”

He said if the Peace wasn’t already dammed, the delta could withstand the impact of Site C.

“However, because these changes come on top of many existing impacts, and in conjunction with a compromised recharge, this increment is an important part of creating the ‘straw that breaks the camel’s back,’ ” he writes.

BC Hydro filed a letter in response to Dr. Carver’s submission, rejecting his analysis, arguing the impacts of Site C will not be felt more than 550 kilometres downstream.

“BC Hydro sees no technically valid concern related to the study area boundaries, nor has Dr. Carver provided one,” states the Crown agency. “The physical changes that are predicted have been taken into account in the [the company’s] environmental assessment of the project.” In a separate submission, however, Parks Canada contends there is “a risk of harm” to the Peace-Athabasca Delta and accuses BC Hydro of “bias and lack of rigour” for ignoring science that supports such concerns. “The study boundary should be determined by the cumulative effects of flow regulation from the three Peace River dams,” states Parks Canada. “The W.A.C. Bennett dam damage is done and no one is going to ask for that dam to be decommissioned. Given that is the case, the tolerance for accepting Site C incremental impacts to downstream environments should be correspondingly low.” The joint federal-provincial review is currently hearing submissions in Fort St. John, in northeast B.C.

VANCOUVER — The Globe and Mail
Published Wednesday, Dec. 11 2013, 9:30 AM EST
Last updated Wednesday, Dec. 11 2013, 6:59 AM EST