Over the last 24 hours, strong winds blowing from the northwest to the southeast over the Great Lakes has caused massive downwelling events and temperature swings.
Overnight in Lake Erie, strong winds caused surface water temperatures to drop and bottom waters to warm as the 77-degree surface water mixed with the 53-degree bottom water creating a uniform temperature water column around 74 degrees and breaking up the thermocline.
While this is visually dramatic, it pales in comparison to the temperature changes in Lake Michigan, where the surface water temperature on the Port Stanley buoy (about halfway up the east side of Lake Michigan) dropped from 75 degrees at 7 p.m. on August 21 to 48 degrees at noon on August 22.
In Lake Erie, buoy data shows that temperature change has had an effect on dissolved oxygen (DO) levels. DO levels bottomed out to below 1 mg/L and less than 1% saturation around August 13 and stayed there until around noon on August 22. They have now returned to nearly 100% saturation levels.
Cleveland Water staff continuously monitors conditions in Lake Erie like temperature and DO levels and adjusts the water treatment processes at the four water treatment plants accordingly to ensure delivery of a clean, safe, and consistent product to all its customers. People who trawl Lake Erie hoping to catch the big one may want to note these temperature and dissolved oxygen fluctuations as it can impact the depth of water in which you catch fish.
Above: Water Temperature Changes in Surface Water (red) and Bottom Water (grey) at Cleveland Water’s Crib Buoy from Aug. 10 to Aug. 24
Above: Dissolved Oxygen Changes in Cleveland Water’s Crib Buoy from Aug. 10 to Aug. 24