Muskegon Lake Water Quality Dashboard


water quality monitoring

The Muskegon Lake Long-Term Monitoring Program began in 2003, in an effort to observe and document changes in the ecological health of Muskegon Lake and provide the data needed to remove Muskegon Lake from the list of Great Lakes Areas of Concern (AOC). As part of the program, the lake is sampled 3 times per year at 6 sites for a suite of biological, physical, and chemical parameters.

Muskegon Lake buoy observatory

As a complement to the long-term monitoring program, the Muskegon Lake Observatory was established in 2011. The observatory consists of a buoy system that collects continuous water quality, hydrology, and meteorological data during the ice-free period.

Key water quality indicators were selected from these datasets to create a water quality dashboard for Muskegon Lake. The goal of the dashboard is to provide a visual representation of the current status and historical trends in Muskegon Lake water quality, by rating each indicator along a scale from desirable (green) to undesirable (red) conditions. Each scale also includes a category that indicates the water quality goal for the lake is being met (yellow). A grayscale version of the dashboard is also available.

We selected dashboard indicators that are commonly used to assess water quality and are relevant to AOC delisting: total phosphorus (TP), chlorophyll a, Secchi disk depth, and dissolved oxygen. Each indicator is described in more detail below.

COVID-19 restrictions prevented spring water quality sampling in early May 2020 and delayed the deployment of the Muskegon Lake Observatory Buoy until August 2020. In the past, we presented annual averages for the three seasons that we sample; since 2020, we have presented the dashboard as seasonal averages across sites to reveal the changes over time in the lake and provide greater detail on lake changes. When dashboard data are organized by season, the influence of spring data on annual means (as shown in prior dashboards) is revealed. For example, lower TP and chlorophyll a values in spring offset the larger TP values in summer and fall when averaged over the entire sampling season, obscuring the seasonal differences; conversely, the deeper Secchi disk values in spring (i.e., clearer water) counter the shallower summer and fall seasonal depths (i.e., more turbid water).

The 2021 data indicate that Muskegon Lake’s annual water quality means generally improved from 2019. It is unclear if the COVID-19 pandemic had any influence on 2020 water quality data, as restrictions and changes in social behaviors may have limited recreational use in Muskegon Lake. While our long-term monitoring program provides useful information to evaluate lake water quality trends over time, the limited sampling effort (6 sites, 3×/yr) can miss important episodic events. For example, very intense harmful algal blooms formed in Muskegon Lake in fall 2021, which were not captured as part of the long-term monitoring work. The lake’s ecological health, while certainly improved from the industrial era (Steinman et al. 2008; Liu et al. 2018), still has room for improvement.


Total Phosphorus

Target Concentration: 30 µg/L

Current Status

(2021)

Spring 2021 total phosphorus = 7 ug/L
Summer 2021 total phosphorus = 29 ug/L
Fall 2021 total phosphorus = 39 ug/L

Historical Status

(1972, 2003-2021)

All 2003-present sampling Spring means are all desirable and very low compared to historic 1972 data.
2003-present sampling has ranged between desirable, meeting goal, and undesirable values; however, 2021 summer TP was less than 2020.
Mean Fall 2021 TP was undesirably high and the second highest fall measured since 2003.

As one of the key nutrients that fuels algal growth, phosphorus concentration can indicate the potential for a lake to sustain undesirable algal blooms. The phosphorus dashboard was created by calculating seasonal average TP concentrations measured in the surface water of the 6 long-term monitoring stations. Historical data collected by the US EPA (Freedman et al. 1979) are included as a reference point for historical conditions.

Spring and Summer TP concentrations have decreased from 2019 through 2021, falling within the thresholds of the Desirable and Meeting Goal statuses, respectively. However, fall TP concentration was almost 40 µg/L, extending well into the Undesirable category.  Overall in 2021, the mean TP concentration (25±16 µg/L) and spring and summer TP concentrations have been falling into the meeting goals or desirable categories for most of the past 10 years; however, fall TP concentrations have been undesirable two of the past three years.

 

Data sources: Freedman et al. (1979); Muskegon Lake Long-term Monitoring Program, Steinman et al. (2008) and AWRI (unpublished data)


Chlorophyll a

Target Concentration: 10 µg/L

Current Status

(2021)

Spring 2021 chlorophyll a = 4 ug/L.
Summer 2021 chlorophyll a = 9.5 ug/L
Fall 2021 chlorophyll a = 15 ug/L

Historical Status

(1972, 2003-2021)

Spring chlorophyll means are all desirable and very low compared to historic 1972 mean data.
Summer chlorophyll in 2021 decreased from a 5-year streak of undesirable high years.
Fall 2021 mean chlorophyll continued a trend from the past several years of high undesirable concentrations.

Chlorophyll a is the green pigment found in photosynthetic algae. Measuring chlorophyll a is one way to estimate the amount of algal biomass present in lake water. The chlorophyll a dashboard was created by calculating annual average chlorophyll a concentrations measured in the surface water of the 6 long-term monitoring stations. Historical data collected by the US EPA (Freedman et al. 1979) are included as a reference point for historical conditions.

Similar to the TP data, spring mean chlorophyll a concentrations were low and in the Desirable range, while summer values were in the Meeting Goal range and fall concentrations remained Undesirable.  The very large decline in summer is encouraging but Muskegon Lake also had very significant fall harmful algal blooms that were not captured by our long-term monitoring program.  Sampling by EGLE revealed microcystin (the most common toxin produced by cyanobacteria, also known as blue-green algae) concentrations far in excess of EPA standards for recreational waters. This result merits careful watching in future years.

Mean chlorophyll a from the Muskegon Lake Observatory (2 m depth) was 5.7 (±1.5) µg/L in May, 10.8 (± 3.8) µg/L in July and 14.8 (± 5.1) µg/L in fall, closely matching lake-wide seasonal sampling. 

 

Data sources: Freedman et al. (1979); Muskegon Lake Long-term Monitoring Program, Steinman et al. (2008) and AWRI (unpublished data)


Secchi Disk Depth (Water Clarity)

Target Depth: 2.0 m

Current Status

(2021)

Spring 2021 Secchi disk depth = 2.7 m.
Summer 2021 Secchi disk depth = 2.3 m.
Fall 2021 Secchi disk depth = 1.9 m.

Historical Status

(1972, 2003-2021)

Spring means in recent years have ranged in the Meeting Goal category and Desirable categories.
Summer Secchi disk depth in recent years ranges between the undesirable and meeting goals categories.
Fall Secchi disk depth in recent years ranges between undesirable and meeting goal categories.

Secchi disk depth is an estimate of water clarity, measured using a standard black and white disk. Low water clarity can be the result of algal biomass, suspended particulate matter, or natural staining of the water. The Secchi depth dashboard was created by calculating annual average Secchi depths measured at the 6 long-term monitoring stations. Historical data collected by the US EPA (Freedman et al. 1979) are included as a reference point for historical conditions. Unlike TP and chlorophyll a, the larger (i.e., deeper) the Secchi depth number, the better the water quality. 

In 2021, the status for spring Secchi depth improved to Desirable from the prior six years, and the summer Secchi depth improved to the Meeting Goal category. However, the fall Secchi depth was shallower, indicating more turbid water, and falling into the Undesirable category after three prior years of meeting goal.  The shallower Secchi depths in fall are consistent with the greater chlorophyll a concentrations at that time.

 

Data sources: Freedman et al. (1979); Muskegon Lake Long-term Monitoring Program, Steinman et al. (2008) and AWRI (unpublished data)


Dissolved Oxygen

2021 Mean % Days < 2 mg/L: 39%
Target Mean % Days < 2 mg/L: 25%

Current Status (2021)

Muskegon Lake had low DO for  39% of 2021.

Low Dissolved Oxygen (<2 mg/L): Bottom Waters, % Monitoring Period (May-October)

The current status of the dissolved oxygen indicator decreased from 2020 to 2021 and falls within the Undesirable category, as indicated by the almost 40% of time with DO concentrations less than 2 mg/L. This represents a substantial decline in oxygenated conditions at the lake bottom over the past three years, and in combination with the high fall TP, chl a, and microcystin concentrations, warrant continued monitoring of lake water quality. Buoy deployment in 2021 ranged from May 20 through October 27 with no data gaps due to downtime.

Historical Status (2011-2021)

Muskegon Lake DO in recent years has ranged between undesirable and meeting goal categories.

Data source: Muskegon Lake Observatory, B. Biddanda (unpublished data)

Well-oxygenated water is critical to the healthy functioning of aquatic ecosystems, including sustaining populations of fish and bottom-dwelling organisms, such as insects, worms, mollusks, and snails. In overly-productive (i.e., eutrophic) lakes, dissolved oxygen (DO) can become depleted in the bottom waters, particularly during summer months. The DO dashboard was created by calculating the percentage of time during the annual monitoring period (May-October) that the daily average DO was less than 2 mg/L in the bottom waters at the Muskegon Lake Observatory buoy.


Acknowledgements

We are very grateful to the many people associated with collecting the data on Muskegon Lake that help inform this dashboard, including Bopi Biddanda, Mike Hassett, Maggie Oudsema, Brian Scull, Terry Boerson, Tim Halloran, Eric Hecox, Emily Kindervater, Jasmine Mancuso, Rachel Orzechowski, James Rahe, Ian Stone, Autumn Taylor, and Sean Woznicki.

We also gratefully acknowledge the Community Foundation for Muskegon County and the National Oceanic and Atmospheric Administration (NOAA) for helping to fund the monitoring efforts in Muskegon Lake.


References

Freedman, P., R. Canale, and M. Auer. 1979. The impact of wastewater diversion spray irrigation on water quality in Muskegon County lakes. U.S. Environmental Protection Agency, Washington, D.C. EPA 905/979006-A.

Liu, B., McClean, C.E., Long, D.T., Steinman, A.D., and R.J. Stevenson. 2018. Lake eutrophication and recovery over a 200-year period of post-native American settlement was determined by a complex set of local and regional factors. Science of the Total Environment 628-629: 1352-1361.

Steinman, A.D., M. Ogdahl, R. Rediske, C.R. Ruetz III, B.A. Biddanda, and L. Nemeth. 2008. Current status and trends in Muskegon Lake, Michigan. Journal of Great Lakes Research 34: 169-188.



Page last modified March 1, 2022