Straight from the Tap

Lake Erie Water Levels Drop Below 573.4 Feet

10/02/2020

For the first time in 258 days, Lake Erie Water levels have dropped below 573.4 feet. This level is significant as it marks the Ordinary High Water Mark for Lake Erie, which is based on International Great Lakes Datum 1985.

The daily average water level for the entire lake was above this measurement from January 12 (573.47 feet) through September 25 (573.42 feet), before decreasing on September 26 to 573.38 feet.

This stretch of very-high water is one of the longest in the history of recording water levels on Lake Erie, which started in 1860, and includes three months with record-setting water levels. Those months and their monthly average water levels were March at 574 feet, April at 574.33 feet, and May at 574.4 feet, which broke previous records set in 1986, 1985, and 2019 respectively.

Water levels have dropped about 5 inches (0.41 feet) since September 1. It is expected that Lake Erie water levels will continue to decrease throughout the fall due to evaporation. Evaporation rates are greatest in the fall to early winter when there is the greatest differences between the cold air blowing over the lake and the temperature of the surface water.

The water surface temperature offshore of Cleveland has decreased from 76.82°F to 67.9°F and the once stratified layers in Lake Erie have begun to mix, as shown in the data coming from our water quality buoy 15 miles offshore.

Temperatures measured by the buoy show water temperatures throughout the water column are no longer layered but mixed at 66.6°F. The water closer to shore, measured by our crib buoy, is also mixed and about 1 degree warmer. This is also about the average temperature of the water coming into each of our four water intakes. At the beginning of September, water coming into our intakes was 8.1 °F warmer, averaging 74.7°F. 

While the daily, seasonal, and annual fluctuations in lake levels do not have an impact on our water treatment process or quality, you may notice a temperature difference at your tap. This is because the water flowing through our water mains and out of your cold water tap is usually within 5°F of the water temperature in Lake Erie.

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