Evaluating alternative transmission line alignments that traverse the deepest lake in North America

Taltson Hydro Expansion Transmission Route Comparison

To better serve electricity needs in Canada’s remote North, the Government of the Northwest Territories (GNWT) and their partners are proposing to expand hydroelectric generation at the Taltson Twin Gorges station on the Taltson River. This includes a new transmission interconnect between the expanded generation station and the existing Snare Hydro System to the north.

This initiative is a partnership between the GNWT, Akaitcho Dene First Nations, Salt River First Nation, and Northwest Territories Métis Nation. A steering committee of senior leadership from all groups is overseeing the project’s direction and decision-making.

Taking on the challenge of determining how the transmission line would cross Great Slave Lake, the deepest lake in North America, the partners identified two technically viable transmission routes. They engaged us to facilitate comparison of these two routes, building on existing studies, data, and feedback obtained during engagement sessions and Indigenous knowledge workshops.

The first option follows existing transmission lines along a road corridor for most of the route. The second option is shorter and involves a submarine cable across Great Slave Lake with a new overhead alignment. The two routes offer significant differences in length, cost, risk profile, and public perception. 

A key focus for us has been incorporating the perspectives of the project’s Indigenous partners. To that end, we presented data on the potential routes to impacted Indigenous groups and solicited their feedback and knowledge to shape the project’s direction. Additionally, we studied the potential environmental impacts of using submarine cable and methods to mitigate those impacts and considered the employment and business opportunities of each alignment. Based on our presentations and discussions with Indigenous partners, the project is considering the transmission route involving submarine cable across Great Slave Lake and initiating preliminary engineering design.  

By integrating hydroelectric capacity into one grid, the project will provide a clean energy solution for the mineral-rich region. This streamlined capacity will better meet the needs of mines in the region, increase the overall reliability of the system, and eventually stabilize electricity rates for over 70 percent of the NWT population.