Storage Enhancements

Storage enhancements increase the amount of water stored in an existing reservoir, resulting in the ability for a hydro facility to generate more electricity. This can be done by changing the water licence for the reservoir to increase the upper allowable water level, decrease the lower allowable water level, or do both.



We examined two options for the 2016 Resource Plan: enhanced storage on Mayo Lake and on the Southern Lakes (Marsh, Tagish, and Bennett lakes).

AECOM completed a series of planning studies on the Southern Lakes in 2009. Work has continued under Hemmera. The enhancement concept involves raising the licensed Full Supply Level by 30 cm and decreasing the Low Supply Level of Marsh Lake by 10 cm.

Studies on the Mayo Lake Enhanced Storage Project started in 2008 as part of the Mayo B project. Environmental monitoring, socio-economic studies and consultation was completed in 2015. This enhancement project would see the current Low Supply Level decreased by up to one metre.

Technical and Financial Findings

Annual Energy Firm Energy Installed Capacity Dependable Capacity Levelized Cost of Energy Levelized Cost of Capacity Project Life In-service Lead Time
GWh/yr GWh/yr MW MW $/kWh $/kW yr Years Years

Option #1

Marsh Lake

9.98 9.98 N/A N/A $0.09 N/A 34 3

Option #2

Mayo Lake – 1m

7.54 7.54 N/A N/A $0.11 N/A 45 4

Option #3

Mayo Lake – 0.5m

6.05 6.05 N/A N/A $0.14 N/A 45 4




Aquatic environment Most favourable
Terrestrial environment Most favourable
Air quality Most favourable
First Nation lands Somewhat favourable
Traditional lifestyle Most favourable
Heritage resources Most favourable
Tourism/recreation/other land uses Most favourable
Cultural/community well-being Somewhat favourable
Local economic benefits Least favourable
Climate change risk Most favourable
  •  Most favourable
  •  Somewhat favourable
  •  Least favourable


Storage enhancement studies on the Southern Lakes concept show that the likely effects are subtle, mainly adding to erosion and groundwater issues that already exist. Research shows there should be no significant impacts on water and land animals and their habitats.

Studies on the Mayo Lake project show that sediment is restricting flow at the Mayo Lake outlet channel. There are also operational challenges related to icing and flooding on the lower Mayo River. Research has concluded that these two issues should be addressed before proceeding with the project.

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Initial key findings


Provide additional winter energy, when demand is highest

No need to build new infrastructure

Reduces need for thermal (diesel and LNG) generation