In 1997, the Chicago City Council passed a groundwater ordinance prohibiting the installation of new potable water supply wells. The purpose is to limit the potential for persons to be exposed to potential contaminants by ingesting groundwater. Since new potable wells are prohibited, groundwater contamination is not a potential source of exposure for the vast majority of sites in the city.

Limiting the potential exposure pathways posed to workers by ingesting or inhaling soil makes cleanups more practical and cost effective. Site owners enrolled in the Illinois Site Remediation Program must still test and evaluate groundwater impacts from their site; however, the City of Chicago and the Illinois EPA have a memorandum of understanding which acknowledges the City’s groundwater ordinance as an acceptable “institutional control” under the state’s Tiered Approach to Corrective Action Objectives (TACO) guidelines, limiting the need for groundwater remediation.