The U.S. Army Corps of Engineers measured record low water levels in two of the North America's Great Lakes, Michigan and Huron. The water levels at Lake Michigan and Lake Huron reached the lowest level from 1918, since modern record-keeping began. Water levels at Lake Michigan and Lake Huron broken records the past two months, and the levels have been very near record lows for the last several months. Lake Michigan-Huron's water levels have also been below average for the past 14 years, which is the longest period of sustained below-average levels since 1918.
According to hydrologists, the relatively warm and dry weather over the past year have caused water levels to drop. Long-term weather patterns can cause water levels on the Great Lakes to fluctuate by as much as several feet over a period of years. Hydrologists had been expecting the lakes to dip to a record level, given the relatively warm and dry weather over the past year. The depths of Lakes Michigan and Huron are in constant flux because of a complex combination of factors, including precipitation levels and evaporation rates as well as the amount of water flowing into them from Lake Superior down the St. Marys River and out of them through the St. Clair.
Water levels are tracked by gauges placed around Lake Michigan and Lake Huron, which are technically considered one body of water connected by the Straits of Mackinac. Daily measurements are then averaged at the end of each month for record-keeping purposes.
The experts said the new low-water mark means the lakes are headed into "uncharted territory". The lakes are now lower than they have ever been for any month since modern record-keeping began. According to a retired Army Corps hydrologist Roger Gauthier, it would take years of consistent rain to naturally improve the situation.
The U.S. Army Corps of Engineers reported that in January the Lake Michigan plunged below its previous record low-level, set in March 1964. The water is now more than 2 meters (6 feet) below the record high, set in October 1986.
"At these numbers, it would take years of consistent rain to naturally improve the situation. Water levels can be restored responsibly by gradually installing sills at the head of the St. Clair River. . . . It's time for governments to work to finish the job, before we have further disasters." Roger Gauthier, a retired Army Corps hydrologist
Humans also have played a role by dredging the St. Clair River, which is the main outflow for the lakes. Deepening the river's channel to open the door for oceangoing freighters has increased the amount of water that can flow out of Michigan and Huron, into Lake Erie, over Niagara Falls and, eventually, out to the Atlantic Ocean. Dredging and riverbed mining in the St. Clair dropped the long-term average of the lakes by about 40 cm (16 inches). Great Lakes water-level study recently completed by the U.S. and Canadian governments revealed that unexpected erosion since the last major St. Clair dredging project in the early 1960s dropped the lakes' long-term average by an additional 7- 13 cm (3 to 5 inches). That means the lakes today are nearly 60 cm (2 feet) lower than they would be if there were no human activity around St. Clair's riverbed.
And another problems for which are humans responsible are industrial and agricultural pollutants, sewage discharges, shoreline development, overfishing and a swelling number of invasive species.
A lake of any size is a dynamic system, subject to constant change. Sometimes slightly more water comes in than goes out, or vice versa, and the lake level changes in response. The Great Lakes are no different, only much more complex. Some of the factors affecting lake levels are evaporation, precipitation, crustal rebound, wind, dredging, diversion, flood control and power generation.
Experts warn that the region will experience increased algal growth and concentration of pollutants due to a potential reduction of wetlands and an increased average temperature, which would make lake water more susceptible to pollutants. Relatively low water levels will impact the consumption of water from the Great Lakes region. Low water levels will also impact future energy sources and recreational/economic activity. Specifically, low water levels will reduce the ability of existing hydroelectric stations to generate power because they will have less water from which to harness power. Low water levels will also inhibit access to existing docks and facilities for commercial and recreational use, causing shipping companies to be driven out of business and the closure of recreational marinas.
Lower water levels will exert some of the most significant impacts on terrestrial and aquatic coastal ecosystems. Reduced water levels will modify or eliminate wetlands that function to maintain shoreline integrity, and therefore, reduce erosion, filter contaminants, absorb excess storm water, and provide fish and wildlife habitat, because coastal wetlands function as important staging, breeding, and wintering habitat for waterfowl and breeding and nursery areas for many fish. Lake level effects are the most important natural cause in determining the expansion and contraction of wetland classes. These fluctuations would “change the position of the water line along the shore and therefore change the shape of the zone that wetland vegetation would inhabit". Further, although some wetlands that directly border the Great Lakes shores might be able to shift toward the low water levels, some enclosed wetlands would eventually dry up and transform into another ecosystem over time.
NOAA Great Lakes Water Level Observations
Current Great Lakes-St. Lawrence Water Levels
Sources: JSOnline, University of Michigan, US Army Corps of Engineers
Featured image: Low lake levels in Traverse City, Michigan (Photo: Mark Breederlan, via Michigan Sea Grant)