If you were out on Great Slave Lake last night, you may have noticed the water was a little lower than usual.
According to Environment and Natural Resources Canada’s hydrometric data for Great Slave Lake at Yellowknife Bay, water levels dipped from 156.532 metres to 156.281 metres just before 11 p.m. last night – a difference of about 25 cm.
From there, the water rose again to 156.511 metres at 11:30 p.m. and plummeted back down to 156.358 metres just after midnight.
Mikey McBryan, of Ice Pilots NWT fame, posted photos of a partially drained Back Bay on Facebook this morning.
“Yellowknife Mystery. Back Bay Drained out last night at Midnight. Very creepy,” McBryan wrote.
According to McBryan, the water levels dropped for about 30 minutes before rising back to normal.
Nathen Richea, director of water management and monitoring with the Department of Environment and Natural Resources, said the low water levels were likely the result of sustained winds from the south.
“When winds are from a particular direction for a sustained period and wind direction aligns with a lake’s orientation or fetch, increased water levels can occur,” stated Richea in an email to Yellowknifer.
“Once the winds recede or reverse, water levels rebound or can drop for a short period of time until the water levels equalize on the lake.”
This wind effect is fairly common and is more noticeable with north-south winds, Richea added.