Yukon has a history of hydro projects that have been built out over time to increase their size and meet our growing needs. The Whitehorse, Aishihik, and Mayo facilities all started small and grew over time as the need for electricity increased. Directive criteria #2 asks that the technical work consider the scalability of future sites to ensure we have the same flexibility to grow and manage costs.

Scalability was addressed by the team from two perspectives: project design and inter-jurisdictional transmission.

Project Design

A hydro development can be scaled in two ways. Adding more turbines at a specific site and adding new cascading projects on the watercourse can add both energy and capacity. The Scalability Assessment Report first reviewed the historical designs of the ten (10) hydro sites to re-size them for a better match between our electricity needs as identified in the forecast and to reduce reservoir size and drawdown impacts. Each site was then assessed to see how it could be scaled up over time or combined with others projects to create a set of cascading projects. The following sites remain after the final screening process.

Site Name
Existing Lake Area
Incremental Reservoir Footprint
Total Reservoir Footprint
Gap Closure
Detour Canyon
0 km2
130 km2
130 km2
Fraser Falls
0 km2
311 km2
311 km2
Granite Canyon
0 km2
173 km2
173 km2
Two Mile Canyon
0 km2
101 km2
101 km2
False Canyon + Middle Canyon Run of River
109 km2
154 km2
263 km2
Slate Rapids + Hoole Canyon Run or River
37 km2
154 km2
191 km2


All of the projects are capable of producing winter energy, but there are tradeoffs. When designing a hydro site, one must balance four key factors:

  1. the amount of energy produced
  2. when the energy is produced and spilled
  3. the flooding footprint
  4. the reservoir fluctuation levels (or drawdown)

Each of the sites is capable of producing significant amounts of electricity in the summer because natural river flows are high (e.g. lots of water/fuel is available). If we do not capture high summer water flows by storing surplus water in a reservoir, then it is spilled (wasted), which can negatively affect the economics of the project.

Each element (energy output, reservoir footprint and drawdown) is interlinked with the others. If the reservoir footprint is decreased this results in higher drawdown, and less energy. If the drawdown is decreased this results in a larger reservoir footprint. The current site designs were created with the goal of maximizing energy output while minimizing flooding and drawdown effects.

Technical Paper – Yukon Next Generation Hydro and Transmission Viability Study: Scalability Assessment Report

Inter-jurisdictional Transmission

Yukon is an islanded grid. This means we cannot sell excess electricity to, or purchase electricity from, neighbouring markets when it benefits us. Connecting the Yukon grid to a grid in BC, Alberta, or Alaska could mitigate the risk of producing too much or too little electricity for our needs and provide additional flexibility to our grid.

There are several factors to consider when connecting a grid, and trading electricity between jurisdictions.

  1. Operating practices and standards must be managed under an inter-jurisdictional body and technical and operational upgrades might be required.
  2. Having a connected grid provides options and flexibility as long as the neighbouring jurisdiction is in need of electricity and a price can be negotiated.
  3. Interconnected grids make the most sense when the connected jurisdictions need power at different times. For example, BC and California make great trade partners because BC has higher winter electricity needs for heat and light and California has higher summer electricity needs for air conditioning.
  4. Most grids are connected in a webbed system meaning electricity can move along more than one route from one jurisdiction to another. On a radial grid, like in the Yukon, electricity would travel along one line between jurisdictions with no backup for line failure or load interruptions.

In order to determine how a grid connection could mitigate risk for Yukon two technical papers were developed, one to examine the technical requirements and cost of potential transmission lines, the other to examine the market feasibility of buying and selling power to other jurisdictions.

The reports studied two potential transmission lines, one to Iskut, BC, and one to Fairbanks, Alaska. The line to B.C. was analyzed with a potential Next Generation Hydro site in southeast Yukon and without. A third option to Skagway, Alaska has been studied in a separate report as part of the Southeast Alaska Economic Corridor Viability Assessment.

The technical assessment report concluded that transmission lines to Yukon’s neighbours are long and costly to build, and they have a low carrying capacity, meaning they are not able to transfer a large amount of electricity. Essentially the lines can be thought of as long skinny straws that cannot move a lot of electricity. As a result, the benefits of constructing a transmission line for electricity trade with Yukon’s neighbours do not outweigh the costs.

Interconnection Option



Capital Cost


Capital Cost $/MWh

Potential Net Yukon Export Capacity(MW)


287KV from Whitehorse to Iskut

763 km





Option 1 with Watson NGH

763 Km





230KV line from Aishihik to Delta Junction (Fairbanks AK)





The market assessment report concluded that given the potential price at which we can import and export energy, the combination of long transmission lines, relatively small Yukon demand, and low carrying capacity of the transmission lines render a transmission connection to Alaska or BC uneconomic.

To provide a sense of scale the Yukon would need to export 227MW per hour, 24/7/365 for 60 years to defray the cost of the Iskut, BC transmission line, and this is approximately equivalent to 6 Whitehorse facilities operated solely for the purposes of export. Unfortunately, even if the export capacity was available, the transmission line does not have the transfer capacity to carry 227MW of power.

Interconnection Option

Export revenue ($M) New Transmission Cost ($M) New Generation Cost ($M) Net Benefits ($M)
YK – BC 214 -1310 -379 -1470
YK – Fairbanks 202 -1015 -379 -1190

Definitions for chart:

Export Revenue – is the anticipated revenue that Yukon could generate after import purchases based on the carrying capacity of the lines and projected sale price.

New transmission – is the cost of the new transmission line.

New Generation Cost – The transmission report calculations were completed assuming that no specific next generation hydro project had been chosen. Still, in order to engage in electricity trade the Yukon would need additional capacity to sell to neighbours so 30MW of new capacity was assumed to complete the modelling.

The conclusions from these studies demonstrate the remoteness of the Yukon grid and the relatively high connection and transmission costs as a result. The biggest risk of building a single transmission line to the south is its vulnerability. A single connection line could be interrupted at a moment’s notice and relying on this to service the Yukon’s population or a mine could be risky.

Different economic scenarios could shift the case for transmission to our neighbours. For example, should the BC or Alaska grid continue to be pay for grid extensions to the Yukon border or should a new mine or industrial project open closer to the Yukon border, the business case may be enhanced.

Technical Papers