By Tony Briscoe
Chicago Tribune
CHICAGO — Since hitting a record-low water level two years ago, Lake Michigan has been replenishing at an almost unprecedented rate, rising more than 3 feet since January 2013, according to government agencies.
Experts say the swift, unexpected resurgence has provided relief to commercial shipping, recreational boaters and wildlife. However, the rising waters have also contributed to significant erosion that threatens local beaches and may damage other shoreline properties as forecasts anticipate this pattern to continue through summer.
The Great Lakes are the world’s largest source of freshwater, and some of those lakes have experienced a decade-and-a-half of below-average levels. Lake Michigan lost 4 feet of water in the late 1990s, and its levels remained low for an unusually long period.
“It just stayed below average for 15 years, which was the longest persistent below-average (stretch) on record,” said Drew Gronewold, hydrologist for the National Oceanic and Atmospheric Administration. “People were asking, ‘Will the water levels ever go up again?’”
For the first time since the late 1990s, the water levels of the Great Lakes rose above their historical averages late last year. Lakes Michigan and Huron, at their highest levels since 1998, experienced the second largest gain over a 24-month span since the Army Corps of Engineers began keeping records in 1918. For measurement purposes, the two lakes are considered one body of water because they are linked by a strait.
While a number of factors contribute to fluctuations in lake levels, including air temperature, humidity and wind speeds, research suggests that the catalyst of the 15-year drought was a strong El Nino, an ocean current that brought about warmer waters and greater evaporation rates.
“The bottom line was, in the Great Lakes, water was warming faster than the air,” Gronewold said. “When you have warmer water temperatures and colder air, there is more evaporation.”
The weather system’s impact was exacerbated by hot, dry summers and winters with minimal snow, according to Keith Kompoltowicz, chief of watershed hydrology for the Army Corps of Engineers in Detroit. The combination of the dry spell and El Nino eventually culminated with water levels for Lakes Michigan and Huron plummeting to a record low of 576 feet, 2 3/4 feet below the historical average, in January 2013.
“For visitors, where there was water, there was the emergence of aquatic vegetation, and the nice sandy beaches became these overgrown weedy areas,” Kompoltowicz said.
While 2 feet might seem minuscule, the impact on the shipping industry was colossal. For every inch of immersion a freighter loses to low water, it must forgo 270 tons of cargo, according to Glen Nekvasil, vice president of the Lake Carriers’ Association, an organization that represents 16 American companies that transport raw materials, such as iron ore and flux stone, for the steel industry.
At the time of the January 2013 drop, the decrease could have cost some of the large freighters as much as 7,000 tons of cargo per trip.
Because of restored lake levels, one freighter shipped nearly 70,000 tons of iron ore, almost a full load, across Lake Michigan in June, Nekvasil said.
The Great Lakes Basin has largely been rejuvenated thanks to rain-induced runoff and higher amounts of precipitation, which have continued in Chicago as the National Weather Service recorded more than 7 inches of precipitation in June — double the monthly normal. Lower temperatures also mitigated evaporation, in addition to ice cover from the past two winters affected by polar vortexes.
“All three components have led to a surge in water levels,” Gronewold said. “It’s not just more rain. It’s not just less evaporation.”
But Gronewold said it’s hard to predict all the factors that might affect the lakes.
“Not a lot of people forecast the Arctic polar vortexes six months out, and those had a tremendous impact,” Gronewold said. “There are a lot of long-term trends on the regional scale that have an indirect effect on long-term climate.”
While water levels grew 3.1 feet in Lakes Michigan and Huron, bested only by a rise recorded in 1950-51, Lake Superior, the largest of the Great Lakes, also saw dramatic gains from the beginning of 2013 through the end of 2014. It rose roughly 2 feet, its highest net increase ever recorded for a two-year period.
However, Lakes Michigan and Huron are currently less than a foot above average, far from when their levels swelled to a record 582 feet, 4 1/2 feet above average, in 1986, experts said. The current levels are forecast to rise in July and August before receding for the following four months, prompting some concerns about storms conditions.
“With the higher water levels, it’ll be interesting in the fall months to see if there are very strong storms that get the lake churned up with waves and the impact on the shoreline,” Kompoltowicz said.
Sheli Lulkin, president of the Association of Sheridan Condo/Co-op Owners, still recalls how storm waves routinely crashed against the second-floor windows of her Edgewater condominium in 1986, sometimes breaking them and sending spray as high as the fifth floor.
“I remember seeing the Streets and Sans people tied together with a rope so as not to get pulled into the lake when they were doing sandbagging,” Lulkin said.
The shoreline of Lulkin’s neighborhood was guarded with rock revetments shortly after. Today, those same revetments, though recently hidden by the recent rising lake levels, have continued to protect the buildings against crashing waves from storms, Lulkin said, including an Oct. 31 storm that created 20-foot-plus waves on Lake Michigan that damaged Chicago’s lakefront bike path and washed water onto busy Lake Shore Drive.
Since about 2000, the Army Corps of Engineers and the city of Chicago have worked to rebuild 9 1/2 miles of deteriorated revetment, woodpile cribs filled with stones in the shape of steps or limestone, some dating to the early 1900s, that were so badly worn over the years that “it went crumbling into the lake,” according to Roy Deda, deputy of project management for the Army Corps.
Last month, state and city officials held a ribbon-cutting ceremony for the completion of a section of the project from Montrose Avenue to Irving Park Road. The agencies are currently working on revetments near Fullerton Avenue that were damaged during the Oct. 31 storm.
Though property along the shore has largely been spared with help from the revetments, local beaches, including Kathy Osterman Beach, also known as Hollywood Beach, have been shrinking in the wake of Lake Michigan’s re-emergence, Lulkin said.
While this may be a disappointment to beachgoers, the ebb and flow of the Great Lakes is beneficial to the ecosystem as far as wildlife is concerned, said Harvey Bootsma, associate professor at the University of Wisconsin at Milwaukee’s School of Freshwater Sciences.
“To go through these cycles of drying and drownings, it’s helpful to the wetlands,” Bootsma said. “Rising lake levels create new wetlands that help spawning for certain species such as pike.”
Bootsma said there is also believed to be a relationship between lake levels and the paralytic, often-fatal disease avian botulism when it comes to aquatic birds, such as sea gulls and cormorants.
“When you see a rapid drop or low lake levels, you see more avian botulism, more birds dying,” Bootsma said. “We don’t know why though. We don’t know how the two are tied together.”
While lake levels and their effect on their surroundings remain a mystery, Bootsma may have the most fail-proof theorem of all.
“These are huge natural systems, and there’s little we can do when it comes to their levels,” he said. “The last 100 years, you can see they do fluctuate quite a bit. But high or low, someone is always going to complain.”
———
©2015 Chicago Tribune
Visit the Chicago Tribune at www.chicagotribune.com
Distributed by Tribune Content Agency, LLC.