The Midwest has an embarrassment of riches right now as the Lake Michigan-Huron system enters its sixth straight month of record water levels, a mere 12 cm below its all-time high:
The lake is nearly 3 feet higher than usual for early summer and approaching the historical high, set in October 1986, according to the U.S. Army Corps of Engineers, which maintains the official records for all of the Great Lakes.
As Chicagoans return to the lakefront and the 18-mile Lakefront Trail, which officially reopens in most areas Monday, they will notice waves lapping onto flooded pathways, disappearing beaches, submerged breakwaters and stone revetments unable to hold back the pulsating water.
“If people haven’t been back to the beach or their favorite spot in a while, it may be very different with erosion or a lot less beach,” said John Allis, the Army Corps’ chief of the Great Lakes hydraulics and hydrology office, based out of the Detroit District. “Conditions can be very different on the coastline than people may be used to in the past.”
The high water levels can be seen up and down Chicago’s shoreline. Near Belmont Harbor, the path for walkers and joggers that skirts the inner part of the harbor was partially covered with water on Monday. Runners dodged water or splashed gingerly on their way. Nearby, a section of the trail was blocked with barricades and a bright yellow warning sign: “Caution Undermining Erosion.”
The Belmont Harbor Dog Beach was almost entirely submerged, with only a small spit of sand available for dogs and their owners. “It’s gone,” one woman mentioned to her companion as they walked past, “It’s underwater.”
Scientists say a confluence of factors has contributed to the high water: recent record precipitation complete with drenching downpours, milder winters and warming overall temperatures throughout the Midwest.
Heavy rains in the spring and summer of 2019 raised lake levels, setting the table for the record highs of 2020.
Warmer temperatures mean fewer blasts of cold air, less ice cover and less-than-normal evaporation since cool surface water is a driver of evaporation, said Lauren Fry, a physical scientist with NOAA’s Great Lakes Environmental Research Laboratory.
“Climate factors,” Fry said, “are the primary drivers of water levels.”
The Lake Michigan-Huron system is already the largest freshwater lake in the world, with an area of 117,400 km² and the largest source of fresh water in the hemisphere. It also used to be a lot bigger: only 8,000 years ago, the lake came all the way up to Clark Street, before the ice dam holding it back gave way in what must have been one of the most spectacular hydrologic events in the planet's history. (If I ever get a time machine, that's one of the things I want to see. That, and the moment the Atlantic Ocean breached the Strait of Gibraltar, creating an epic flow of water that may have filled up the Mediterranean Basin in only two years.)