Tag: Drew Gronewald

The Changing Great Lakes: Living with Fluctuating Water Levels

High Lake Michigan water levels have overwhelmed popular beaches, such as this one at East Bay Park at the base of East Grand Traverse Bay. Photo by Holly Wright.

By Dave Dempsey and Jim Olson

This spring, water levels on all five of the Great Lakes have reached, or are approaching, record highs. The result of unusually high winter and spring precipitation, increased winter ice cover and reduced evaporation, these new highs are the latest in a never-ending series of Great Lakes level fluctuations. The levels have typically fluctuated by as much as 7 feet in recent geologic times. However, studies show that climate change is causing or contributing to more rapid swings between high and low water levels. Just six years ago, Great Lakes levels were below normal, and in some portions of the Great Lakes watershed, citizens clamored for new underwater structures to hold back water in an attempt to boost upstream water artificially.

Now the problem is high water, which creates several concerns:

  • The residences of lakeshore property owners may be at risk of foundational erosion, flooding and even toppling into the lake.
  • Coastal infrastructure, such as roads and bridges, is vulnerable to erosion damage and destruction.
  • Public access to the shoreline may be limited, both because of inundation of prime publicly-owned coastal land and because high water will intrude beyond the ordinary or naturalhigh-water mark, the limit of access adjacent to private property.
  • Taxpayers may be asked to pay the bill for erosion control, moving of structures away from the lake, and/or damages.

In a recent article published in The Conversation (an online magazine devoted to “academic rigor and journalistic flair”), University of Michigan scientists Drew Gronewald and Richard Rood  say they “believe rapid transitions between extreme high and low water levels in the Great Lakes represent the ‘new normal.’ Our view is based on interactions between global climate variability and the components of the regional hydrological cycle. Increasing precipitation, the threat of recurring periods of high evaporation, and a combination of both routine and unusual climate events – such as extreme cold air outbursts – are putting the region in uncharted territory.”

Supporting their observations, water levels have also tumbled dramatically in the last several decades. In 1998-99, the water levels of Lakes Michigan and Huron dropped 25 inches in 12 months.

The public often asks whether governments can do something to raise or lower levels. But the fact is that human engineering can do little in this regard. While there are laws for setting or modifying inland lake levels, increasing outflow from one lake to the next often has a ripple effect downstream. The problem will only worsen with increased precipitation and water levels now experienced in the Great Lakes region. Similarly, manipulation of water level control structures to address lower water levels can, in turn, lower any one of the lakes only a few inches. Only one percent of the volume of the Great Lakes flows out of the system annually. Far bigger influences are precipitation and evaporation.

Members of the public also ask whether they can still walk the beach when water levels are above the ordinary or high-water mark that defines the boundary between state ownership and private riparian ownership. As a practical matter, the public should still be able to enjoy a right to walk the beach and shores of the Great Lakes—provided it is safe—so long as they remain in the zone along the water’s edge that is wet or compacted by recent wave and other natural forces of nature.

The International Joint Commission (IJC) observes, “Unlike oceans, where tides are constant and predictable, water levels on the Great Lakes can vary significantly in frequency and magnitude making them difficult to accurately predict.” A US-Canada treaty body, the IJC is responsible for maintaining control structures at Sault Ste. Marie, Niagara Falls and the meeting point of Lake Ontario and the St. Lawrence River.

A popular misconception is that warming temperatures associated with climate change will significantly lower Great Lakes water levels. But the effect of climate change on these levels is unclear. Warmer air holds more moisture, leading to an increasing number of heavy rain and snow storms. In fact, some models predict rising Great Lakes levels as a result of climate change.

To minimize our contribution to climate change and to protect our Great Lakes ecosystem, we should reduce our use of fossil fuels and we should push our elected leaders to act on climate change. However, given that human effort can do relatively little to alter quickly-changing Great Lakes water levels, adaptation should be our societal response.

Resources

Great Lakes water level update, U.S. Army Corps of Engineers

Great Lakes water levels, International Joint Commission

Great Lakes Water Levels and Related Data, Government of Canada

Jim Olson is founder and president of FLOW; Dave Dempsey is senior advisor.