‘There was some growing concern': Extreme heat events potentially impacting Lake Erie conditions

CTV News

5 days ago

Extreme heat waves are impacting the Great Lakes and may have negative impacts on the health of the ecosystem. CTV London's Gerry Dewan reports.
Local researchers are keeping an eye on Lake Erie temperatures, with warmer conditions creating potential risks.
It was a surge in the lake's average surface temperature that caught Mike McKay's attention, with those temperatures reaching around 27 degrees Celsius, 'Last week there was some growing concern, as the temperatures were starting to reach what had been, in recent years, the highest temperature for mid-July. That was (established) 2020.'
McKay is the director of the Great Lakes Institute for Environmental Research at the University of Windsor.
He told CTV News that extreme heat warnings issued by regional health units in late June and early July were also impacting the lake. Overnight temperatures in the 20s offered little relief and contributed to a rare phenomenon known as hypoxia.
According to McKay, 'Hypoxia is when usually deeper waters in the lake lose their oxygen.'
PORT STANLEY BEACH
A boat passes near the beach at Port Stanley on July 23, 2025. (Gerry Dewan/CTV News London)
That can have three impacts; the first is discoloured water in the drinking water supply, not dangerous but also not pleasant. It can also contribute to the blue-green algae, with farm fertilizer stored in sentiment on the lakebed getting stirred up and feeding the algae. McKay said the third issue is the detrimental impact on small creatures that are an important part of the food chain.
'Which really is what drives the impressive fishery we have in Lake Erie. Lake Erie has roughly 2 per cent of the water in the Great Lakes, but about 50 per cent of the fish,' explained McKay. 'So, the commercial fishery on the Canadian side, the massive recreational fishery on the U.S. side.'
The average surface temperature has slipped to 24 degrees this week, but with another surge in high temperatures expected, McKay said he and other researchers will be closely watching the impacts on Lake Erie.