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.

2020 Water Levels

Updated January 2021.

Introduction:

This is an update to the July 2020 report of high water levels in the Saugatuck and Douglas harbor area. Saugatuck and Douglas continued to experience high Kalamazoo Lake and River water levels through the end of 2020, but the water level is down significantly (~17 inches) from the record highs of the summer. Note that the present water level (approximately 581 ft. msl) is still significantly higher (approximately 31 inches) than the long term mean January elevation of Lake Michigan (approximately 578.4 ft. msl). The lake level forecast provided by the US Army Corps of Engineers (USACE) indicates that the water level over the next 6 months will be slightly below the record highs of last summer, but again above average in respect to the long-term mean. 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 Understand:

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 previously in the July 2020 report 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 six 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 relative to the historic maximum, minimum, and mean water levels. The first nine months of 2020 each set a new record high mean water level. The mean water level for July-August 2020 was ~582.4 ft. msl, 7.3 inches higher than the previous maximum set in 1986 (581.79 ft). Starting in mid-September 2020, the water has receded to a present value of 581 ft. msl, down approximately 17 inches. The presently reported water level of 581 ft. msl typically represents the seasonal low value.

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 (January 2021):

Presently Lake Michigan and thus Kalamazoo Lake are at 581 ft. msl which is approximately 42 inches above the low water datum (LWD) value. Water level is down approximately 6.7 inches from the mean January 2020 level (which was a record high for January) and 17 inches from the record high set in July 2020. However, the water level today is still approximately 31 inches higher than the long term average. The water level will rise again in the late spring due to river runoff and snow melt and peak in the July time frame.

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 6 month period starting from January 2021. Recall, three factors determine lake level; precipitation, evaporation, and runoff which is referred to as the Net Basin Supply (NBS).

In the summer of 2020 a La Niña event occurred in the Pacific Ocean. Recall a La Niña is where surface waters of the Pacific at the equator are colder than average. Such events drastically affect the weather in the Great lakes, in this case typically resulting in a wetter and colder winter. The USACE uses historical La Niña (cold) and El Niño (warm) events and how these events influence water level to make better predictions.

Figure 3 shows the range of predicted water level for the next six months based on the influence of the La Niña for Lake Michigan. The gray area represents the range of possible modeling scenarios based on data from 1900 to 2020, from a June 2021 level below 580.4 ft. (~7 in. below the present level and 14 inches above the long term June average) to approximately 582.7 ft. (approximately 4 inches higher than the record high water event of 2020). The four solid lines represent water level projections based on conditions observed in four La Niña years that were similar to 2020. For example, the green curve represents the projected water level if the conditions (i.e. air temperature, winds, precipitation) over the next six months resemble those from 1971. The scenario deemed most probable based on historical precedent would be a relatively safe June water level of approximately 581.48 ft msl (approximately 6 inches below the sea wall). However, three of the four scenarios (1996, 2008, and 2011) project water levels near or above 582 ft msl, lower than last year’s record high but still sufficient to cause further flooding. All four modeled years show increased water level, again due to a La Niña generating a wetter winter in our part of the Great Lakes region. Thus, precipitation is the big driver in respect to lake levels.

Summary:

The high water has 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, the warm fall Lake Michigan waters (still at 39.9 degrees F) and colder air temperature led to above average evaporation, resulting in the reduced NBS as discussed above. The takeaways are:

1. Kalamazoo Lake and Lake Michigan are hydrostatically connected, if Lake Michigan rises so does Kalamazoo Lake and River.
2. Remember the number 582 ft msl. When the gauge at Holland reads 582 ft or higher we are going to get flooding.
3. 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.
4. 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.

Prior water level reports from July 2020 and December 2019 are also available.