The water levels, the lowest since modern record-keeping began in 1918, 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.
The relatively warm and dry weather over the past year have hydrologists saying the record low levels do not surprise them.
"Not only have water levels on Michigan-Huron broken records the past two months, but they have been very near record lows for the last several months before then," John Allis, chief of the Army Corps' Great Lakes hydraulics and hydrology office, told the Milwaukee Journal Sentinel.
"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."
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, but the new low-water mark means the lakes are headed into uncharted territory, experts said.
"At these numbers, it would take years of consistent rain to naturally improve the situation," Roger Gauthier, a retired Army Corps hydrologist, said in a Sierra Club of Canada release.