Your 2020 HAB Guide

DHS Logo Original 07/11/2018

Harmful Algal Blooms


Your 2020 "Quick Reference" HAB Guide

A long overdue "hello" from the DPH HAB Program! 

Many of us have been so deeply buried in COVID-19 prevention and response efforts that we feel rudely awakened when we're reminded that other public health threats exist. Exposure to blue-green algae and their toxins is just as much an environmental health hazard as it ever was, and with individuals spending even more outdoor time with their families and pets this summer, several reports of related human and animal illnesses have already been submitted to our Division of Public Health Harmful Algal Blooms Program (DPH HAB).

With recent high humidity and soaring temperatures, your jurisdiction may have already received reports of blooms, and more may be on the horizon. The DPH HAB Program wants to help you prepare for effective messaging to the public about HABs and water safety, as well as provide you with the resources you’ll need to address blooms and related illnesses. Below, you'll find a compilation of FAQs, quick links, sample social media posts, and other resources to help you prepare for the 2020 HABs season. Be sure to save this guide for quick future reference!


What if I receive a report of a blue-green algae bloom?
If you receive a report of a bloom without an accompanying illness, report the bloom to the Wisconsin Department of Natural Resources (DNR). Include descriptions of bloom size, duration, and location with lake, town, and county name, and photos taken both close-up and farther away. The DNR is unable to sample and test in response to each bloom report, but may be able to confirm whether cyanobacteria are present from submitted photos. Please note that this email address is monitored during normal business hours, so responses to reports received outside business hours may be delayed.

What if I receive a report of a human illness suspected of being related to blue-green algae?
Blue-green algae (cyanobacteria) and cyanotoxin poisoning is now a Category II reportable condition in Wisconsin. Cases must be reported to the local public health department of the jurisdiction where the ill person resides within 72 hours of case recognition. Local health departments should report the suspect case to WEDSS as soon as possible and reference the Case Reporting and Investigation Protocol for guidance. Due to the complexity of case investigation and risk assessment, the DPH HAB Program will work with local health and tribal agencies on case investigations. The HAB Program has been investigating suspect cases of HAB-related illness for over 10 years and will continue to offer technical assistance, including possible water sampling, to local health and tribal agencies during case investigations.

What if I receive a report of an animal illness suspected of being related to blue-green algae?
Report the suspect case to the DPH HAB Program. The HAB Program will work with the local health agency to investigate the illness. Suspected blue-green algae-related illnesses in animals are important to report because they may serve as sentinels for human illness.

Who has the authority to close a public beach or swim area due to a human health hazard (e.g., blue-green algae), and when can they do it?
Per Wis. Stat. § 254.46, “the... local health department shall close or restrict swimming, diving and recreational bathing if a human health hazard exists in any area used for these purposes on a body of water and on associated land and shall require posting of the area." Local health departments and tribal agencies have primary authority for issuing health advisories, beach or water body closures, and public messaging. An exception exists for state parks and state forests; at many of these locations, the DNR will post signage and close public beaches.

Local health and tribal authorities can issue a health advisory and close a public beach due to blue-green algae when testing or visual observation suggests a high probability of adverse human health effects (>100,000 cells/mL cyanobacterial cell density, elevated cyanotoxin concentrations, or a visible cyanobacteria scum layer is present).

When can a beach be reopened?
Reopening a swim beach can depend upon follow-up test results, visual inspection of the water quality, and allowing time for cyanobacteria and cyanotoxin levels to drop. If your jurisdiction is interested in developing or readjusting a monitoring program for HABs, please visit the Environmental Protection Agency's Recommendations for Cyanobacteria and Cyanotoxin Monitoring in Recreational Waters.

Quick links


Did you know that the DPH HAB Program now offers signage? Signs are available in PDF and aluminum metal formats. Please email the HAB Program for prototypes, pricing, and more!

HAB signs

Four designs are available, including: “Scan Before You Swim,” "Caution," “Beach Closed,” and “Is it Blue-Green Algae…Or Something Else?” The last illustrates common blue-green algae bloom conditions in Wisconsin as well as non-harmful water conditions often confused with blooms.

HAB sign photo

Green Lake County health officer Kathy Munsey (left), and public health nurse Rachel Prellwitz (right), show off new blue-green algae beach signs. Metal signs are made of high quality aluminum and are offered in 9”x12” and 12”x18” sizes. Metal 6.5’ stakes are also available for purchase.

Introducing our New HAB Program Epidemiologist


Meet Xiaofei He

Xiaofei He obtained her MPH in Epidemiology and Ph.D. in Health Communication from the University of Minnesota-Twin Cities. She completed her postdoctoral training in Quantitative Population Health Sciences at Dartmouth College. Prior to working as a seasonal helper for the HAB Program, she worked as an epidemiologist for the Wisconsin Sportfish Consumption Research Program at DHS. While Xiaofei has worked with lots of data on fish and lake contaminants, she is brand new to the HAB topic and is excited to learn more. This summer, she will help provide public education about HABs and work closely with local public health and the DNR to investigate related illnesses. Welcome, Xiaofei!

Social icon

Let's Get Social

Suggested social media posts and accompanying photos:

Heading to the lake? Be on the lookout for blue-green algae! Keep your family—especially young children and pets—away from water with noticeable discoloration or surface scum, foam, and algal mats. Learn more: 


If you’re bringing Fido to the beach, remember to be on the lookout for blue-green algae. Avoid stagnant water and areas with noticeable discoloration or surface scum, foam, and algal mats. Give your pup a rest from fetching and bring along fresh, clean water for him to drink. Learn more:  

Blue-green algae dog

Did you know that blue-green algae blooms have look-alikes? Learn the difference and when in doubt, stay out! Learn more about blue-green algae:

BGA guide

Stay in Touch


Missed a past issue? Previous issues are available on our Resources for Health Professionals webpage.

Email us your burning questions! If others can benefit from hearing the answer to your question, we’ll feature it in a future issue.

Remember that we are always available for consultation on any HAB health-related issue by email or phone (608-266-1120).