Is Bay Beach Safe to Open?

As the City of Green Bay prepares to open Bay Beach for swimming, the threat of blue-green algae continues to loom. At the end of March of this year, Mayor Schmitt announced the city has received all the necessary permits to construct a sand beach, fishing pier, boardwalk, and bathhouse at Bay Beach Amusement Park. Having an area in Green Bay to publicly access the water would be a huge asset to the community. However, some researchers are not confident that the city should let the public swim in the bay yet due to the presence of blue-green algae. [1][2]


  • Blue-green algae is not actually algae. It is a cyanobacteria, which, like algae, is photosynthetic and grows with the increase of nutrients, such as nitrogen and phosphorus. The watershed surrounding the bay has been releasing excessive amounts of phosphorus over the years, allowing the cyanobacteria to flourish. In addition, cyanobacteria grow fastest in warmer shallower water, such as the water in Green Bay. [3][4]
  • Cyanobacteria can release cyanotoxins. Exposing humans to these toxins can cause a variety of symptoms:
    • Respiratory Symptoms (brought on by swallowing or breathing in (such as from spray from boating) cyanobacteria):
      • Sore throat
      • Congestion
      • Cough
      • Wheezing
      • Difficulty breathing
      • Eye irritation
    • Dermatological Symptoms (which can be avoided by showering immediately after swimming):
      • Itchy skin
      • Red skin
      • Blisters
      • Hives
    • Other Symptoms:
      • Earache
      • Agitation
      • Headache
      • Abdominal pain
      • Diarrhea
      • Vomiting

Pets and young children are especially susceptible. Symptoms for pets include lethargy, difficulty breathing, diarrhea, seizure, weakness, and vomiting. Exposure to cyanobacteria can ultimately result in death for humans and pets. [5]

  • There has not been enough research in the bay to create a model to properly predict the growth of algal blooms. The WDNR is not required to test for cyanobacteria when monitoring beaches. [6] When the WDNR approved the permits for Bay Beach, they based their decision on a three-year study that was requested by the city. According to other researchers, three years is not enough time to properly evaluate the water quality in terms of cyanobacteria. [7]
  • Although the study performed for the city came up with moderate levels of cyanotoxins along Bay Beach’s shoreline, they admit they may have missed some samples that could show higher levels because the algae is difficult to catch. [2][8] Additionally, there have been studies by NEW Water that have samples with much higher levels. One in September 2017 presented 4,000 micrograms per liter of cyanotoxins, which is 1,000 times greater than the EPA’s recreational guideline set at 4 micrograms per liter. [2][7]
  • Blue-green algae is not a threat the entire summer season. Since cyanobacteria develops when the water becomes warmer, swimmers/people recreating will most likely not be affected near the beginning of summer. [3] However, they should be made aware of cyanobacteria as soon as it appears.
  • The City of Green Bay is currently working on a monitoring and reporting plan which will be vital to ensure they are not risking the health of their citizens. [2]

Given the information above, do you think the City of Green Bay should wait longer to open up Bay Beach for swimming?



  1. https://www.greenbaypressgazette.com/story/news/2018/03/30/green-bay-gets-approval-restore-bay-beach-swimming/473608002/
  2. https://www.greenbaypressgazette.com/story/news/2018/07/09/bay-beach-restoration-algae-bacteria-coli-concern-but-wont-slow-return-swimming-green-bay/738672002/
  3. https://intellegereproject.files.wordpress.com/2018/08/hab-booklet.pdf
  4. https://dnr.wi.gov/lakes/bluegreenalgae/
  5. https://www.dhs.wisconsin.gov/water/bg-algae/healthconcerns.htm
  6. https://dnr.wi.gov/lakes/bluegreenalgae/
  7. https://intellegereproject.files.wordpress.com/2018/08/new-water-final-white-paper-bay-beach-2-2018-1.pdf
  8. https://intellegereproject.files.wordpress.com/2018/08/blrpc_bay_beach_restoration_action_plan_08-24-15_jn.pdf

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