The Dynamic Great Lakes
Water levels in the Great Lakes have always been highly variable. They fluctuate over time in response to wind, storms, precipitation and evaporation from the lakes’ surfaces and runoff from tributaries.
Seasonal variation occurs every year as the lakes rise an average of 12-18 inches from winter to early summer. Long-term fluctuations lasting many years, decades or longer are visible in the historical record (US Army Corps of Engineers). Each Great Lake is unique in how it responds to the factors that influence lake levels: it depends on the size and composition of the lake’s watershed, total volume of the lake basin and other characteristics. The lakes also influence each other’s levels, as they are all interconnected.
One common concern when considering varying lake levels is how climate change could affect the Great Lakes and coastal communities. Michigan Sea Grant created a suite fact sheets, hosted workshops and developed educational lessons to address what residents, communities and leaders need to know about changing lake levels.
Fluctuating Lake Levels
With more than 3,200 miles of Great Lakes shoreline, lake levels have a huge impact on Michigan’s coastal communities and economies. Lake levels affect coastal properties and infrastructure, plant and wildlife habitat, shipping, recreation and manufacturing.
When levels fluctuate much above or below the long-term average, the impacts can be significant, especially in highly developed areas where infrastructure was not designed to withstand changing levels. Michigan Sea Grant is working on coastal community planning initiatives to address the impact of fluctuating lake levels on the boating industry and other coastal-dependent businesses. See: Vibrant Waterfront Communities
Ups and Downs
Whether future climate matches the predictions of scientists, consider this: it doesn’t matter. The reality is that weather, climate and lake levels will continue to be variable. Instead of reacting to the highs and lows in temperature, precipitation and lake levels, it is important for coastal communities to expect and prepare for these ups and downs.
Plan for Highs and Lows
In Michigan, the weather changes frequently and sometimes drastically. Water levels also naturally fluctuate daily, seasonally and over decades. The changing climate adds yet another layer of variability.
Scientists expect trend of extremes to continue
In recent decades, we have experienced more severe and frequent extreme events, like major storms and heat waves. Regardless, climate and lake levels will continue to change. Building coastal infrastructure expecting low levels to persist indefinitely may leave communities unprepared for when levels rise again. A best practice is to prepare for a range of outcomes.
- U.S. Army Corps of Engineers Great Lakes Water Level Update.
- Great Lakes Shoreviewer (Superior Watershed Partnership): Tool allows users to visualize risk to buildings, infrastructure, and shorelines.
- Coastal erosion reporter (Superior Watershed Partnership): Citizen science tool allows users to report erosion or other coastal hazards around Lake Superior and the Upper Peninsula shoreline.
- Shoreline erosion information sheet (Michigan Department of Environmental Quality): Explains high-risk erosion areas, such as coastal sand dunes, which have extra state-designated building and development restrictions.
- High risk erosion areas: Programs and maps (Michigan DEQ): Planning resources for high-risk areas.
- Great Lakes lake level viewing tool (NOAA Digital Coast): Tool allows users to adjust lake levels and visualize how areas will be affected.
- Great Lakes water level dashboard (NOAA Great Lake Environmental Research Laboratory): Tool package allows users to view current and historical lake levels along with other Great Lakes climate and weather information.
- Great Lakes current conditions and water levels forecasts (US Army Corps of Engineers): Shows current and historical lake levels, as well as six-month projections.
- Eastern Upper Peninsula Coastal GIS Study mapping tool (Eastern UP Regional Planning and Development Commission): Visual representation of historical lake levels and land features.
- State coastal permitting contact list (Michigan DEQ): Map of Michigan DEQ offices and individuals involved with land/water permitting.