Illinois EPA Notifies Lake Bluff Estates Mobile Home Park Community Water System of Confirmed Groundwater Contamination

SPRINGFIELD - The Illinois Environmental Protection Agency (Illinois EPA) is notifying the Lake Bluff Estates Mobile Home Park (MHP) (formerly Rockland MHP) Community Water System (CWS) in Lake County that there has been a confirmed detection of 1,4-dioxane in recent water sampling, exceeding newly enacted groundwater quality standards. The detection at the entry point to the distribution system of the Lake Bluff Estates MHP CWS. Existing Right-to-Know laws require the owner or operator of a CWS to notify all end users when groundwater contamination poses a threat of exposure to the public above the Class I groundwater quality standards. This law establishes methods of notification and strict time frames for providing notice.

1,4-Dioxane (aka p-Dioxane) is a volatile organic compound (VOC), and the United States Environmental Protection Agency classifies 1,4-dioxane as a Group B2 probable human carcinogen by all routes of exposure. According to the Agency for Toxic Substances and Disease Registry, 1,4-Dioxane is used as a solvent in the manufacture of other chemicals and as a laboratory reagent. There is currently no maximum contaminant level (MCL) for 1,4-dioxane.

On December 7, 2021, the Illinois EPA filed amendments of the Illinois Pollution Control Board's (Board) Part 620 groundwater quality regulations to preserve and protect Illinois groundwater and to ensure that the state's groundwater quality standards match current scientific data and methodologies. The Illinois EPA's proposal included a revised groundwater quality standard for 1,4-dioxane, based on the most recent scientific information available. On April 11, 2025, the Board's adopted amendments to Part 620 were published in the Illinois Register, triggering this Right-to-Know notification.

The revised 35 Illinois Administrative Code Part 620 Class I (potable) groundwater quality standard for 1,4-dioxane is 0.78 microgram per liter (µg/L). Any concentration detected above this Class I groundwater quality standard triggers notification pursuant to the Environmental Protection Act. 1,4-Dioxane has been confirmed at the entry point of Lake Bluff Estates MHP CWS distribution system at 0.95µg/L. Lake Bluff Estates MHP CWS consists of 66 direct service lines, supplying drinking water to an estimated 165 individuals.

The Environmental Protection Act requires the owner or operator of the CWS to notify their customers of this contamination by mail, email, post card, text message, or telephone, within five business days of official receipt of the Illinois EPA's notice. Within seven days of sending the notices, the owner or operator of the CWS must provide the Illinois EPA with written proof that the notices have been sent.

This press release and the notice to the Lake Bluff Estates MHP CWS will be posted on the Illinois EPA website at: https://www2.illinois.gov/epa/topics/drinking-water/public-water-users/Pages/notices.aspx. The Illinois Department of Public Health is also being notified due to the detection of 1-4-dioxane, since it is a volatile organic compound exceeding the Class I groundwater quality standard. A factsheet for 1,4-dioxane can be found on the Agency for Toxic Substances and Disease Registry (ATSDR) website at:  https://www.atsdr.cdc.gov/toxfaqs/tfacts187.pdf.