Reporting a Harmful Algal Bloom

If you suspect a blue-green algal bloom on your lake or on a public lake you've visited, you can report it to the Illinois EPA. Complete a Bloom Report Form. (Google Chrome users: You may need to download the form first before opening it. Right-click the link and select "Save link as..." from the menu.) The form can also be obtained from the Volunteer Lake Monitoring Program (VLMP) coordinators listed below.

Fill out as much of the form as possible. Take two photographs of the bloom. One photo should be a close-up of the algal bloom or scum, and the other photo should include the surrounding landscape to help identify the location of the bloom or scum on the lake.

Electronic copies of the photos and form should be submitted to the Illinois EPA at and, if you are a volunteer in the VLMP, your regional VLMP coordinator.

Note: Illinois EPA will review all forms submitted; however, the ability to initiate follow-up activities will be dependent on time and resources of the Illinois EPA at the time of the submittal. Priority will be given to publicly-owned lakes.

  • Alana Bartolai, Lake County Health Department
    (Lake County)
  • Holly Hudson, Chicago Metropolitan Agency for Planning
    (Cook, DuPage, Kane, Kendall, McHenry, and Will Counties)
  • Tyler Carpenter, Greater Egypt Regional Planning and Development Commission
    (Alexander, Franklin, Gallatin, Hamilton, Hardin, Jackson, Jefferson, Johnson, Massac, Perry, Pope, Pulaski, Saline, Union, White, and Williamson Counties)
  • Greg Ratliff, Illinois Environmental Protection Agency
    (Any County)

What Happens Next?

If the Bloom Report and photos support the occurrence of an actual blue-green algal bloom, a HAB responder may be sent to investigate the bloom. The responder could be an Illinois EPA employee or a VLMP coordinator. Illinois EPA will be able to send responders only as time and resources allow.

If a HAB responder is sent to investigate, they will use the Bloom Report Form to locate the bloom and may contact the person reporting the bloom for additional information. They may also collect a sample for analysis of microcystins. If they do, they may analyze the sample using a qualitative test kit (which provides results within 24-36 hrs.). If microcystin is detected above concentrations of concern, the person reporting the bloom and the lake management entity will be notified.

The remaining sample may also be sent for quantitative analysis (with a longer turn-around for results). Again, if levels of microcystin are of concern, results will be provided to the person reporting the bloom and if identifiable, to the lake management entity.

Illinois EPA will not issue an advisory or close a lake due to microcystin concentrations that exceed the high recreational threshold (according to World Health Organization Guidelines). Illinois EPA will provide information to the lake owner and may make recommendations. With information in hand, the lake owner or association, at their discretion, may choose to post an advisory (or close a portion of the lake), warning people of the elevated microcystin levels in the lake.

Follow-up qualitative or quantitative samples may be taken, on a site specific basis, as time and resources allow.

Interpreting Results

The table below outlines the likelihood of acute health effects due to recreational exposure to varying concentrations of microcystin in surface water.

World Health Organization Guidance Values(1)
Relative Probability of Acute Health Effects (Advisory Level)Microcystin-LR(2) (ug/L)Total Cyanobacteria (cells/mL)
Very High>2,000>10,000,000

1. The World Health Organization (WHO) guidance values for the relative probability of acute health effects during recreational exposure to microcystins, based on information presented in Chorus and Bartram, 1999.

2. Although the WHO guidelines are specifically for microcystin-LR, enzyme-linked-immunosorbent assays (the most commonly used measure of microcystins) do not separate microcystin and nodularin congeners. Therefore, total microcystin and nodularin concentrations often are used to assess the probability of acute health effects instead of microcystin-LR concentrations. Graham and others, 2009


Extreme caution should be taken in the case of any exposure to a possible HAB. People and pets should avoid direct contact to, inhaling droplets of, or ingesting any of the water.  When working near or investigating a bloom, safety equipment including: gloves, carpenter’s mask, waders, goggles, and personal flotation devices are recommended. If you or your pets come in to contact with surface water exhibiting signs of a potential HAB, wash immediately with soap and tap water.

Reporting Human or Animal Illness

The Illinois Department of Public Health (IDPH) conducts surveillance for illnesses that may be related to harmful algal blooms, and encourages the reporting of any suspect illness to the health department. If you know of a human or animal illness that may be related to algal toxins, please coordinate the submission of a report form to IDPH. Report forms can be found on the IDPH website.


Chorus I, Bartram J. 1999. Toxic cyanobacteria in water: a guide to their public health consequences, monitoring and management. World Health Organization.

Graham JL, Loftin KA, Kamman N. 2009. Monitoring recreational freshwaters. LakeLine 29:18–24.