Significantly low water levels in Mayo Lake are forcing Yukon Energy to seek emergency amendments to its territorial water licence.
“Water levels on Mayo Lake are among the lowest we’ve seen and the lake isn’t refilling the way it usually does during summer months,” the company said on its website. “This means less water is available to flow through Mayo Lake to support fish habitat downstream in the Mayo and Stewart rivers.”
The emergency amendments, submitted Aug. 1, would allow Yukon Energy to reduce water flows downstream of the lake to the minimum levels required to support fish habitat — 663.25 metres above sea level.
According to the company, water levels today are 663.49 m above sea level. That compares with 665.41 m above sea level on Aug. 14, 2018. Water level throughout August is usually above 665 metres according to records for 10 of last 14 years.
Yukon Energy has a responsibility to protect fish habitat near its facilities and has already worked to minimize the power generated at its Mayo facility to save as much water in the lake as possible, Yukon Energy president Andrew Hall said in an interview Aug. 13.
“But it’s not enough,” the corporation says in its summary.
Hall said the situation is not “100 per cent” fully attributed to climate change.
Right now, it is being looked at as an “unusual” weather situation, though not unheard of in the Mayo watershed, which has had historically low water years in the past.
Hall said Yukon Energy is currently involved in a study looking at what the territory may experience in the years ahead due to climate change, and while the work is not complete, data seems to indicate at this point the territory will see warmer and wetter conditions.
The last time there was a multi-year low was in the late 1990s when it was at about 70 per cent of the average water level.
In that case — prior to Yukon Energy’s Mayo B project that brought with it a number of new water licence conditions to be met — there were no changes to the licence.
If deemed to be necessary, the proposed new amendments would also allow lake water levels to be reduced below the low supply level in order to sustain flows downstream.
As it’s stated in the application to the water board: “The requested amendment will enable Yukon Energy to conserve water in the reservoir to prevent the lake’s elevation from dropping below the level necessary to sustain the minimum in stream flows needed for Chinook salmon spawning, and for spawned salmon eggs to stay wetted after the spawning period. If this amendment is not granted on an emergency basis, it is likely that there will be a significant adverse impact on spawning and/or egg incubation habitat.”
If the changes are approved, water levels in Mayo Lake and downstream would be lower than their current low levels, Hall said, stressing the corporation’s efforts to always stay within its water licence requirements.
While Yukon Energy officials are viewing the situation as a temporary one, Hall said if there were a multi-year drought scenario, the corporation would work to share information with the Village of Mayo and the First Nation of Na-Cho Nyäk Dun to ensure all government bodies are aware of any changes.
“We’re confident these measures will help us maintain fish populations in the short term,” the company’s summary says. “We’ll continue to monitor water levels and fish conditions over the long term, and share and discuss our findings with the Village of Mayo, the First Nation of Na-Cho Nyak Dun, and the Yukon government. We will make the modifications needed to minimize impacts of extended drought conditions should that occur.”
Hall said the corporation also put its amendment forward to the Department of Fisheries, which said Yukon Energy does not require its direct approval, though it will need the water board to approve the application.
The water board is set to meet Aug. 14 to review the application, with Hall anticipating a prompt reply to follow, potentially by the end of the week.
Contact Stephanie Waddell at stephanie.waddell@yukon-news.com