​The 2021 Harmful Algal Bloom Program comprises two parts: Routine Monitoring and Event Response. Routine Monitoring targets public-water-supply intakes in Illinois lakes, streams, or Lake Michigan; lake beaches; or Lake Michigan nearshore areas. Event Response investigates cyanobacteria blooms in publicly owned lakes or in streams where blooms may threaten public health. All cyanobacteria-toxin samples are sent to the Illinois EPA Division of Laboratories for analysis. For beach samples, the lab analyzes primarily for the toxin, microcystin. For samples from public-water-supply intakes, the lab analyzes for three additional toxins: cylindrospermopsin, anatoxin-a, and saxitoxin. In some situations, Illinois EPA or a designated party collects a sample to distinguish different types of cyanobacteria. A contracted laboratory provides the additional identification

Routine Monitoring

Routine Monitoring occurs at six general locations:

  1. Sites in Fox River (Northern Illinois)
    Illinois EPA or contractual staff collect a sample approximately every six weeks at each of four Fox River sites (DT-06, DT-09, DT-22, DT-38), during July through October.
  2. Public-Water-Supply Intakes in Streams
    Illinois EPA or contractual staff collect four samples at each of the ten following sites near public-water-supply intakes in streams, during May through October.
    Salt Fork Vermilion River (BPJ-03)
    Little Wabash River (C-21)
    Skillet Fork (CA-05)
    Illinois River (D-30)
    Fox River (DT-01, DT-14)
    Kankakee River (F-16)
    Mississippi River (J-98, M-02)
    Shoal Creek (OI-08)
  3. Public-Water-Supply Intakes and Nearshore Areas in Lake Michigan
    Illinois EPA collects at least one sample at each of five Lake Michigan intakes, six sites in harbors, and five ​other nearshore sites during August through October. Sampling frequency and number of samples depend on weather conditions.
  4. Beaches in Lakes of the Illinois EPA Ambient Lake Monitoring Program
    Illinois EPA collects one sample per month during June, July/August, and October at beaches in three northern-Illinois lakes and two southern-Illinois lakes (Table 1). 
  5.  Public-Water-Supply Intakes in Lakes of the Ambient Lake Monitoring Program
    Illinois EPA collects one sample per month during June, July, August/September, and October near public-water-supply intakes in seven central-Illinois lakes and five southern-Illinois lakes (Table 1).
  6. Beaches in Lakes of Lake County
    During 05/31/2021 through 09/06/2021, the Lake County Health Department collects a sample approximately every two weeks at a beach in each of twelve lakes (Table 1).


 Table 1. Routine Monitoring at Illinois Lakes

RegionLake NameCounty IEPA Lake CodeSampling Focus


​Northern Illinois

​Lily Lake​McHenry​RTZJ


​Lake Le Aqua Na​Stephenson​RPA
​Grays Lake​Lake​RGK




Central Illinois ​

​Charleston Side

Channel Reservoir




​Public Water Supplies

​Vermont New Lake​McDonough​RDM
​Palmyra-Modesto City Lake​Macoupin​RDZP
​Loveless Lake​Macoupin​WDW
​Greenfield City Lake​Greene​RDZF
​Mauvaise Terre​Morgan ​SDL
​Lake Paradise ​​Coles​RCG ​







Southern Illinois

Forbes LakeMarion​RCD


Carlyle LakeClinton/Bond/FayetteROA​Beach, Public water supply intake
Lake Fairfield Wayne





Public water supply intake​ ​






​Wayne City Side Channel Reservoir​Wayne​RCT
​Raccoon Lake​Marion​ROK

Summerfield-Lebanon-Mascoutah Water Commission Off-Channel Reservoir

​St. Clair​SOL


 Lake County

Lake  BarringtonLake​RTZT
Lake CatherineLakeRTD
​Channel LakeLake​RTI
Countryside Lake​LakeRGQ
​Dunns Lake​Lake​VTH
​Fish Lake​Lake​VTK
​Island Lake​Lake​RTZI
​Loch Lomond​Lake​RGU
​Long Lake​Lake​RTJ
​Slocum Lake​Lake​RTP
​Tower Lake​Lake​RTZF
​Valley LakeLake​RGZM

Event Response

Event Response investigates credible reports of a cyanobacteria bloom. Credible report means direct observation by Illinois EPA staff or observations and pictures submitted by the public to Illinois EPA via our Bloom Report Form or bloomWatch

  1. Direct Observation  
    Illinois EPA field staff collect a sample for the toxin, microcystin, when they observe a cyanobacteria bloom in a lake or stream during routine sampling for resource quality.
  2. Response via Bloom Report Form or bloomWatch Application
    Illinois EPA investigates reported suspected cyanobacteria blooms dependent on availability of resources. We give priority to publicly owned lakes.

Illinois EPA applies a preliminary test to screen Event Response samples typically for the toxin, microcystin, but may include other toxins. When a toxin exceeds relevant thresholds for recreation or drinking water, Illinois EPA notifies appropriate lake-management entities. Illinois EPA may perform follow-up monitoring based on availability of resources.

Program Improvements

In October 2020, the U.S. Environmental Protection Agency awarded a grant ($270,626) to Illinois EPA to improve the Illinois EPA Harmful Algal Bloom Program. Over the next three years Illinois EPA intends to expand public education and awareness of cyanobacteria blooms, improve our ability to respond to blooms, and provide more timely access to available data to help protect human health. Some specific activities include, but are not limited to:

  1. Virtual Workshops on Harmful Cyanobacteria Blooms
    Illinois EPA has contracted PhycoTech, Inc. to conduct six virtual workshops. Two workshops will be conducted each year for the duration of the contract. These workshops help train and educate Illinois EPA staff on how to identify a cyanobacteria bloom, how to collect toxin samples, how to pack and ship samples to the laboratory for analysis, and how to pack and ship samples to PhycoTech, Inc. for  identification and enumeration.
  1. Update the Illinois EPA Webpage
    Periodically, Illinois EPA will update the program webpage to improve content and accessibility of data and information. 
  2. Update Standard Operating Procedures for Collecting Toxin Samples
    Illinois EPA will update the standard operating procedure for collecting cyanobacteria toxins in lakes and streams.
  3. Collaborate with the Illinois Department of Public Health
    The Illinois EPA will work with the Illinois Department of Public Health to create social-media content about cyanobacteria in Illinois waters. This content readily provides relevant information to a wide audience.
  4. Create Manual for Responding to Cyanobacteria Blooms
    Illinois EPA will write a manual on how to prepare for a large-scale cyanobacteria bloom. This document will include, but is not limited to, a discussion of toxin-level thresholds of concern, a contact list of relevant personnel, toxin-collection guidelines, and examples of news releases and other appropriate ways to alert the public (e.g., posted warnings at sites).


Historical HAB Information

2020 Statewide Harmful Algal Bloom Program

2019 Statewide Harmful Algal Bloom Program

2018 Statewide Harmful Algal Bloom Program

2017 Statewide Harmful Algal Bloom Program

2016 Statewide Harmful Algal Bloom Program

2015 Statewide Harmful Algal Bloom Program

2014 Statewide Harmful Algal Bloom Program

2013 Statewide Harmful Algal Bloom Program

2012 Drought and HAB Reconnaissance Monitoring Effort 

Working Together Toward a Statewide Harmful Algal Bloom Program 

Blue-Green Algal Toxins in the Ohio River