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.

The indicators shown below are commonly used to assess water quality. We selected total phosphorus, chlorophyll a, Secchi disk depth, and dissolved oxygen to assess lake status, from among the many parameters that we monitor. Each indicator is described in more detail below.

The data indicate that Muskegon Lake’s water quality in 2019 declined from 2018; some indicators were suggestive of undesirable conditions, indicating 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

(2020)

Spring 2020 total phosphorus = no data.

Summer 2020 total phosphorus = 30.35 ug/L

Fall 2020 total phosphorus = 28.37 ug/L

Historical Status

(1972, 2003-2020)

No Spring 2020 total phosphorus data is available but 2003-present sampling Spring means are all desirable and very low compared to historic 1972 data.

Summer total phosphorus was very high and undesirable in 1972; while recent 2003-present sampling has ranged between desirable, meeting goal, and undesirable values, 2020 mean summer total phosphorus slightly crosses the threshold as undesirable.

Recent 2003-2020 mean Fall total phosphorus has been much lower than historic 1972 total phosphorus; mean Fall 2020 is in the middle of this range in the Meeting Goal category.

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 annual average total phosphorus (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.

Summer TP decreased from 2019 to 2020, extending just into the Undesirable status. Fall TP concentration improved from 2019 to 2020, falling within the threshold of the Meeting Goal status. Seasonal TP concentrations overall have been meeting goals or desirable for most of the past 10 years, another positive indicator of lake restoration.

 

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

(2020)

Spring 2020 chlorophyll a = no data.

Summer 2020 chlorophyll a = 27.77 ug/L

Fall 2020 chlorophyll a = 15.64 ug/L

Historical Status

(1972, 2003-2020)

No Spring 2020 chlorophyll a data is available but 2003-present sampling Spring means are all desirable and very low compared to historic 1972 mean data.

Summer chlorophyll a was ~25 ug/L and undesirable in 1972; while recent 2003-present sampling has ranged between desirable, meeting goal, and undesirable values, 2020 mean summer chlorophyll a is undesirable and slightly exceeds historical mean 1972 data.

Fall mean annual chlorophyll a was ~25 ug/L and undesirable in 1972; while recent 2003-present fall sampling has ranged between desirable, meeting goal, and undesirable values, 2020 mean fall chlorophyll a is within the range of recently observed values and falls below the historical 1972 data mean.

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.

Summer mean chlorophyll a concentration decreased from 2019 to 2020 while it increased in the fall; however, its current status in both seasons continues to be Undesirable, as the average seasonal concentrations in 2020 exceeded the water quality goal. Mean chlorophyll a from the Muskegon Lake Observatory (2 m depth), taken every 15 min but deployed later than usual in 2020 (August) due to restrictions from COVID-19, was 8.0 (± 1.2) µg/L in summer and 6.0 (± 2.5) µg/L in fall, suggesting the one-time sampling events each season as part of the monitoring program may have occurred during algal bloom periods. Following the overall seasonal trend seen in total phosphorus, spring chlorophyll a data in the years prior to 2020 were consistently low and in the Desirable range; however, seasonal means in summer and fall have occasionally reached or exceeded the concentrations observed in Freedman et. al’s 1972 pre-restoration 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

(2020)

Spring 2020 Secchi disk depth = no data.

Summer 2020 Secchi disk depth = 1.54 m.

Fall 2020 Secchi disk depth = 2.43 m.

Historical Status

(1972, 2003-2020)

No Spring 2020 Secchi disk depth data is available but 2003-present sampling Spring means in recent years have generally ranged in the Meeting Goal category, which is more clear than the 1972 annual mean Secchi depth, which was undesirable and less clear.

Summer 2020 Secchi disk depth was approximately equal to the 1972 annual mean (both ~1.5 m); however recent years of sampling have been observed closer to the 2.0 m threshold between the undesirable and meeting goals categories.

Fall 2020 Secchi disk depth was 2.43 m, placing it in the meeting goal category and following a trend of recent years becoming increasing clear and approaching the desirable category threshold of 2.5 m.

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. 

The current status for summer Secchi depth is Undesirable, while the fall Secchi depth status remained within the Meeting Goal category. Shallower Secchi depths in summer were consistent with the greater chlorophyll a concentrations at that time. The 2020 Secchi disk data indicated reduced clarity in summer, but improved clarity in fall, compared to 2019. Increased clarity in Muskegon Lake in fall may be due to the reduction of algae via filtering by dreissenid (i.e., zebra and quagga) mussels or natural processes.

 

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


Dissolved Oxygen

2020 Mean % Days < 2 mg/L: 27%
Target Mean % Days < 2 mg/L: 25%

Current Status (2020)

DO dashboard

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

The current status of the dissolved oxygen indicator decreased from 2019 to 2020 and falls within the Undesirable category, meaning there was too large a percentage of days with low DO in 2020. This is likely due to COVID-19 restrictions delaying buoy deployment until August 2020, thereby skipping the spring and early summer months. Earlier dates are when DO is likely to be higher than in mid- to late-summer due to colder water temperatures (which holds more DO) and reduced respiration. The buoy bottom water (11 m) DO sensor operated for ~45% of the 2020 monitoring season, compared to 70% of the 2019 season, 47% in 2018, and 84-97% in 2011-2017.

Historical Status (2011-2020)

DO dashboard

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.