Wet October Slows Typical Seasonal Decline on Lake Michigan

You don’t need rocket science to recognize that it was a very wet October across Michigan’s Great Southwest, but it helps if you have the observations of a hydrologist and the team at the U.S. Army Corps of Engineers at the Detroit District office.

The Great Lakes are experiencing the highest water levels since 1986, and storms and wave action are causing erosion and flooding of the shoreline.  Water levels on the Great Lakes are cyclical with periods of low and high water, with each period lasting for several years depending on the amount of precipitation, runoff, and evaporation that occurs. Great Lakes shorelines include bluffs, floodplains, coastal wetlands, sand dunes, and development, and the type of shoreline determines how high water levels will impact property.

Preliminary precipitation estimates indicate that all of the lakes experienced above average precipitation during the month of October. Precipitation ranged from as much as 8-percent above average in the Lake Superior basin to as high as 86-percent above average in the Lake Ontario basin. The wet conditions led to above average water supplies for Lakes Superior, Michigan-Huron, and Lake Ontario. Although precipitation was above average in the Lake Erie basin, water supplies were slightly below average. Outflows for all of the lakes continued to be above average during October.

The Army Corps says that preliminary estimates reveal that the St. Clair River had record high flows for the month of October.

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Monthly mean water levels for each lake in October were below their record high monthly average levels. From September to October, Lakes St. Clair, Erie, and Ontario continued their seasonal declines and dropped by 4, 5, and 8 inches, respectively. Conversely, Lakes Superior and Michigan-Huron rose less than an inch from September to October, during a time of year when the lakes typically decline.

Seasonal declines are forecasted to continue on all of the Great Lakes this month, except for Lake Ontario, which is forecasted to rise slightly in November before resuming a seasonal decline. However, over the next several months it’s projected that water levels will remain well above average.

Lake Michigan-Huron experienced very wet conditions during the month of October and the monthly mean level for October of 581.66 feet was slightly higher than its September level (581.63 ft.). The October level was 15 inches above its level from one year ago, 33 inches above its long term average level, and 8 inches below its record high level. Precipitation was 57-percent above average for the month, which contributed to higher than average water supplies. Lake Michigan-Huron is forecasted to continue its seasonal decline this month.

Over the next 6 months, the lake is projected to be 1 to 4 inches below record high monthly mean water levels through January, however in February and March the level is projected to be 1 inch above record high levels, which were set back in 1986. In April, the level is predicted to be an inch below its record high level.

Additionally, Lake Michigan-Huron is forecasted to remain above its levels of a year ago by 9 to 17 inches and remain above long term average levels by 32 to 35 inches.

The photo accompanying this story on Moody on the Market is courtesy of award-winning photographer Molly Shuler Pate of Berrien Springs, captured during a stormy mid-October sunset off of St. Joe.