November 2020 Update:
An October 2020 article in the Physics Today magazine highlighted the record high water levels currently being experienced across the Great Lakes region and the impacts that it has had on homeowners in lakefront communities. That article provides useful context for the report below and is available for download below or through the Physics Today website (https://doi.org/10.1063/PT.3.4589).
A PDF version of the report can be found here. This article is reproduced with the permission of the American Institute of Physics.
2021 Water Levels
Updated November 2021.
This is an update to the August 2021 report of water levels in the Saugatuck and Douglas harbor area. Saugatuck and Douglas have continued to experience above-normal Kalamazoo Lake and River water levels through November 2021. However, aside from a short increase following a wet summer, the water levels in Lakes Michigan and Huron continue to decline from the historically high levels experienced in summer 2020. While the mean October water level (580.32 ft. msl) is approximately 24 inches below the summer 2020 peak, it is still approximately 17 inches higher than the long term mean October elevation of Lake Michigan (approximately 578.94 ft. msl). The lake level forecast provided by the US Army Corps of Engineers (USACE) indicates that the water level will continue to decline through the fall and early winter as part of the typical seasonal cycle, but will likely remain above the historic average over the next 12 months. Many stakeholders are again asking what is going on and will the Lake level significantly go down? We will try to address these questions with this discussion, but note the predictions on future lake level are educated guesses by NOAA and USACE scientists and engineers based on modeling Mother Nature.
First Point to reemphasize:
Kalamazoo Lake and Lake Michigan are hydrostatically connected! This means that as Lake Michigan rises, so does the Kalamazoo Lake and River. Kalamazoo Lake is what is referred to as a drowned river mouth.
Historical Lake Levels:
Let’s again look at the updated historical Lake Michigan water levels going back to the year 1918 (Figure 1). As discussed in prior reports, Lakes Michigan and Huron are also hydrostatically connected by the Straits of Mackinac. The time history in Figure 1 shows at least six periods of high water and five low water level events, with a near record low occurring in 2013 (remember all the dredging concerns). Some modelers see a periodicity in high to low water levels of eight to fifteen years, but suffice to say the water level goes up and it goes down at least each decade. If we examine the length of high water events during the entire record we observe high water events as short as one year and as long as approximately eight years. The average duration of high water events is approximately four years. We are presently seven years into this high water event and the plot shows we are trending downward. Good news.
Figure 2 shows in more detail the mean monthly water levels from 2020 and 2021 relative to the historic maximum, minimum, and mean water levels. After water levels reached a record high in July-August 2020 (~582.4 ft. msl, 7.3 inches higher than the previous maximum), the water has steadily declined to a mean October level of approximately 580.39 ft. msl. This is down approximately 2 feet from the record highs of last summer, and 14 inches from the mean October 2020 levels, but still approximately 17 inches higher than the long term October mean.
The top of the seawall at East Shore Harbor Condos (ESHC) is at approximately 582 ft. msl, thus any Lake Michigan water level above 582 ft results in flooding. The 582 ft. msl is representative of the height of other seawalls in the areas, thus if there is flooding at ESHC flooding will be occurring in other parts of the harbor. The mean daily water level for Lake Michigan exceeded 582 ft every day from May 20, 2020 through early September. After that point, the average monthly water level has not exceeded 581.5 ft. msl, thus no flooding. The Lake Michigan water level gauge at Holland can be easily accessed (see NOAA's water level data for Holland, MI) to ascertain whether flooding of the shore is occurring. Just remember ~582 ft. msl or lower equals no flooding.
Present Lake Level and Near Term Trends (November 2021):
Presently Lake Michigan and thus Kalamazoo Lake are at 580.22 ft. msl which is approximately 33.5 inches above the low water datum (LWD) value. Water level is down approximately 16 inches from the mean October 2020 level and 26 inches from the record high set in July 2020. However, the water level today is still approximately 17 inches higher than the long term average. The water level will likely continue to decline through the fall and early winter as air temperatures decline and evaporation increases.
Future Lake Levels:
The US Army Corps of Engineers, NOAA, and various Canadian government organizations all monitor the water level in the Great Lakes and make predictions as to future water levels. Some predictions look a few months into the future while others predict next year or five and ten years out. For this discussion we are presenting the USACE Great Lakes Water Level Outlook for a 12 month period starting from October 2021. Recall, three factors determine lake level; precipitation, evaporation, and runoff which is referred to as the Net Basin Supply (NBS).
Figure 3 shows projected water levels based on a range of scenarios. The purple envelope represents the range of likely water levels based on 10 years that also experienced La Niña conditions in back-to-back years, similar to 2021. In this range of scenarios, the water level will continue to decline through January 2022 before peaking again in Summer 2022. However, this range of scenarios indicates that levels should remain below the 582 ft msl flooding threshold. The much wider gray area represents the range of possible modeling scenarios based on historical data from 1900 to 2020.
The three solid lines represent water level projections if NBS and hydrologic conditions (i.e. air temperature, winds, precipitation) are similar to those observed in three of the 10 back-to-back La Niña years: 1984-85, 1999-2000, and 2017-18. All three scenarios resulted in a continued decline in water levels through spring 2022 while remaining above the long term historic mean and below the historic maximum.
The high water levels of 2020 created problems and large expenses for the harbor stakeholders. The big question that we do not have a reliable answer for is, when if ever will the water return to normal (i.e. is near average value). It really is mostly about the precipitation and evaporation. The average annual precipitation in the Michigan watershed basin is approximately 32 inches, with a high value of 40 inches occurring in 1985 and a low of 21.6 inches in the year 2016. Last year (2020) the annual precipitation in the Saugatuck area was 39.2 inches, near the high. However, a dry winter and spring in 2021 has resulted in a continued reduction in water levels. Current forecasts suggest a likelihood of above normal temperatures over Lake Michigan and equal chances of above-average, normal, and below-average precipitation for the next few months. The takeaways are:
- Kalamazoo Lake and Lake Michigan are hydrostatically connected, if Lake Michigan rises so does Kalamazoo Lake and River.
- Remember the number 582 ft msl. When the gauge at Holland reads 582 ft or higher we are going to get flooding.
- Storm surge and seiche events on Lake Michigan will still occur and result in local flooding due to the high water. In normal times we barely notice these occurrences.
- The future lake level is all about NBS, really it translates into rain and snow fall. Above average precipitation in the Great Lakes Basin spells trouble.
A PDF version of the report can be found here.