We've Moved: The Illinois EPA Headquarters has moved to 2520 W Iles Ave, PO Box 19276, Springfield, IL 62794-9276.

2025 Harmful Algal Bloom Program

The Agency’s 2025 Algal Bloom Monitoring Program consists of two parts: Routine Monitoring and Event Response. Routine Monitoring is conducted at public-water-supply intakes, lake beaches, and public-water-supply intakes in Lake Michigan. Event Response investigates potential cyanobacteria blooms in lakes or streams where blooms may threaten public health. Toxin samples are sent to the Illinois EPA Division of Laboratories for analysis.

Routine Monitoring

Illinois EPA intends to monitor the following waterbodies and locations:

Public-Water-Supply Intakes - Lakes
One microcystin, cylindrospermopsin, anatoxin-a, and saxitoxin sample per month in June, July, August/September, and October near public-water-supply intakes (Table 1).
Public-Water-Supply Intakes – Lake Michigan
Microcystin, cylindrospermopsin, anatoxin-a, and saxitoxin samples at four Lake Michigan intakes between April and November.
Lake Beaches
One microcystin and cylindrospermopsin sample per month in June, July/August, and October at a subset of lake beaches (Table 1).
Beaches - Lake County Health Department
Between May and September, the Lake County Health Department intends to collect a sample approximately every two weeks at fourteen lake beaches and one stream (Table 1).

Table 1. Routine Monitoring at Illinois Lakes

Region	Lake Name	County	Illinois EPA Lake Code	Sampling Focus
Northern Illinois	Crystal	McHenry	VTZH	Beach
	Gages	Lake	RGI
	Grays	Lake	RGK
	Silver	McHenry	RTW

Central Illinois	Charleston Side Channel	Coles	RBC	Public Water Supply
	Decatur	Macon	REA
	Mattoon	Shelby	RCF
	Paradise	Coles	RCG
	Paris Twin East	Edgar	RBL	Beach
Southern Illinois	Glendale	Pope	RAP	Beach
	Holliday Shores	Madison	RJN	Public Water Supply/Beach
	Lake of Egypt	Williamson	RAL	Public Water Supply/Beach
	Vienna Correctional Center	Johnson	RAT	Public Water Supply

Lake County Health Department	Lake Barrington	Lake	RTZT	Beach
	Bangs Lake	Lake	RTG
	Lake Catherine	Lake	RTD
	Channel Lake	Lake	RTI
	Countryside Lake	Lake	RGQ
	Dunns Lake	Lake	VTH
	Fish Lake	Lake	VTK
	Island Lake	Lake	RTZI
	Loch Lomond	Lake	RGU
	Slocum Lake	Lake	RTP
	Tower Lake	Lake	RTZF
	Valley Lake	Lake	RGZM
	Dog Training Pond at Independence Grove Dog Park	Lake	UGH
	Lake Forest Pond at Prairie Wolf Slough County Forest Preserve	Lake	UHG
	Hastings Creek at Duck Farm Dog Pond	Lake	GWAA

Event Response

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

Direct Observation
Illinois EPA field staff may collect a sample for microcystin, cylindrospermopsin, anatoxin-a, and saxitoxin when they observe a potential cyanobacteria bloom in a waterbody.
Response via Bloom Report Form
Illinois EPA may investigate reported potential cyanobacteria blooms. Response is dependent on availability of resources. Publicly owned lakes are prioritized.

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