Few local officials and public servants in Great Lakes coastal communities fully appreciate the potential consequences changing lake levels, flood patterns, and storm events that may result from a changing climate. In part, this is because regional climate and lake level projections are provided via abstract data and charts that do not indicate specific consequences for city planners and other resource managers. Coastal communities need interpretive tools that synthesize dispersed data and translate the predictions of regional climate change models and lake level forecasts into user-friendly, local terms that anyone can understand. Such tools will help decision-makers see the connections between climate model results and the day-to-day decisions they must make.

Potential Risks

  • Coastal Flooding:  Climate change may cause the water levels on Lakes Superior and Michigan to extend beyond the range measured since 1860.
  • Coastal Erosion:  An increase in intense precipitation and storm events along with the impacts of warmer and wetter winters (more freeze/thaw cycles and less lake ice cover) could increase coastal erosion and may lead to more frequent episoidal deep-seated landslides.

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Vulnerabilities

graph of fluctuating water levels of Lakes Michigan and Huron

The historic range of Lakes Michigan and Huron is 1.92 meters (6.3 feet) in the past 90 years.

Source: NOAA Great Lakes Env. Research Lab

  • Residential and commercial structures and property on the coast are vulnerable to erosion and flooding.  The migration of the Ordinary High Water Mark (OHWM) towards the lake during extended periods of low lake levels may encourage development in hazardous areas.
  • Harbors and marinas are susceptible to extreme water levels.
  • Industrial facilities such as power plants and water/sewer treatment facilities are vulnerable to extreme water levels that exceed their design.
  • Infrastructure such as roads and drainage are susceptible to coastal erosion and flooding.
  • Shore protection structures need to be maintained over time and may not be effective if lake levels extend beyond their design parameters.
  • Natural plant communities along the Great Lakes, including coastal wetlands, may be impacted by persistent extreme lake levels.
  • Water intakes may be impacted by low water levels.
  • Climate change may impact tourism in coastal communities.  Issues include beach health and aesthetics for hotels.
  • Changes in water temperatures and circulation patterns could affect mixing patterns in coastal waters.
  • More intense coastal storms could impact dredging and re-suspend contaminated sediments.

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Data Needs

An integrated topographic and bathymetric model of Ozaukee County, WI

Source: Jeff Stone, Association of State Flood Plain Managers

  • Updated long-term projections of potential lake levels based on downscaling of general circulation models for the Great Lakes region.
  • Detailed nearshore bathymetry for multiple time periods to study lakebed downcutting.
  • Current, high resolution LiDAR data to construct integrated topographic/bathymetric models to  visualize the impacts of variable water levels.
  • Current and historical orthophotography to calculate rates of bluff and shore erosion.
  • Parcels, tax assessment data, and planimetric mapping to assess buildings and infrastructure at risk to coastal hazards.
  • Higher density and frequency of coastal observations (buoys and other sensors measuring wind, waves, water levels, etc.).
  • Coastal demographics.
  • Extent of beaches and coastal wetlands.
  • Inventory of shore protection structures.

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Adaptation Strategies

Road failure along Lake Michigan in Door County, WI caused by coastal erosion in October 2007

Source: David Hart, UW Sea Grant

  • Implement development setbacks based on defensible scientific data.
  • Relocate structures that are threatened by flooding or erosion.
  • Education for developers, bankers, and insurance agents.
  • Ongoing comprehensive planning and improved implementation of existing plans.
  • Use best management practices for site design to control stormwater runoff.
  • Develop plans for bluff stability enhancement, e.g. slow erosion by planting vegetation on bluffs.
  • Improve or restore natural shore protection features (beaches, dunes, nearshore shoals, and islands)
  • Design port and harbor infrastructure that can accommodate increased variability in lake levels, e.g. harbor slips that float.
  • Study the impact of climate change on tourism economics.

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Contact

Please contact Gene Clark, David Hart, or Phil Moy at the University of Wisconsin Sea Grant Institute if you have any comments or concerns regarding how our changing climate will impact Wisconsin's Great Lakes coastal communities.