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List of Significant Environmental Hazards Reported to DEEP

Property owners are required to submit information on certain types of environmental conditions to the Connecticut Department of Energy & Environmental Protection (DEEP) when such conditions are encountered during an environmental site investigation or remediation of a parcel. DEEP refers to the reporting of these conditions as "reporting of significant environmental hazards" or "hazard notifications" pursuant to Section 22a-6(u) of the Connecticut General Statutes.

DEEP is required by statute to provide a List of Significant Environmental Hazards Reported to DEEP on the website.  This list is updated periodically, and it contains information on hazard notices reported to DEEP for the period shown in the upper right corner of each page. 

The List of Significant Environmental Hazards Reported to DEEP linked below contains the following information for each entry:


This is the site name and address of the parcel on which the pollution being reported may be located or from which the pollution being reported originated. This is not necessarily the location where the potential environmental hazard condition exists.

Date Notified

This is the date DEEP received the written hazard notification.

Type of Hazard

This is a description of the type of hazard(s) reported to DEEP in the written hazard notification. More than one condition may be identified in a single hazard notification. The types of conditions that must be reported to DEEP are defined in the statute and are summarized below:

  • Public or private drinking water supply wells with detected pollution (above or below an acceptable standard);
  • Polluted groundwater within 500 feet upgradient, or 200 feet in any other direction, of a drinking water supply well with the potential to threaten drinking water supply well water quality;
  • Polluted groundwater beneath or near an occupied building with the potential to pose a risk to indoor air quality;
  • Polluted groundwater discharging to a surface water body with the potential to pose a risk to aquatic life;
  • Polluted soil present within two feet of the surface with the potential to pose a direct contact risk to humans; and
  • The presence of vapors from polluted soil, groundwater or residual free product at levels posing a potential explosion hazard and imminent threat to human health, public safety and the environment.
Initial Response
Upon receipt of the hazard notification, DEEP sends an acknowledgement letter to the property owner to provide written direction regarding any additional steps that may be needed to abate, mitigate, further investigate, monitor, or otherwise address the reported hazard condition(s).  The response listed under this heading is a brief summary of the action(s) DEEP directed the property owner to take. Since July 2015, the law has required an immediate initial responses for some hazard conditions, and submittal, concurrently with the notification, of a report of the initial response actions taken and a plan for further actions to address the hazard condition.  The DEEP acknowledgement letter may include an approval of such reports or plans, and may request additional actions not included in the plans.
These are actions taken by the reporting party or the property owner to abate, mitigate, further investigate, monitor, or otherwise address the reported condition(s). In some cases, a monitoring program that periodically confirms the continued absence of short-term risk may be implemented as an on-going mitigation action.  This list is not intended to include any additional remedial activity beyond the actions needed for abatement or mitigation of the significant environmental hazard under CGS section 22a-6u.

List of Significant Environmental Hazards Reported to DEEP

This list contains information on all hazard notifications submitted to DEEP after October 1, 1998, the inception of the notification requirement. The published list does not include notifications made in error (those which were made but were not required by the law). Sites for which the significant environmental hazard has been permanently abated or is currently mitigated shall be excluded from the list by law, and DEEP is working to filter these from the list. Sites for which DEEP does not have a current confirmation of continued effectiveness of mitigation measures are included on the list, until such time a status report is received by DEEP. Significant Environmental Hazard Notifications not on the published list may be found in DEEP’s Public Fileroom.

The Significant Environmental Hazard Statute is intended to identify and abate short-term risks associated with specific environmental conditions identified in the statute. After abatement of short-term risks (meaning actions that permanently eliminate the short-term risk posed by the significant environmental hazard condition) or mitigation of short-term risks (meaning prevention of short-term exposure risk through interim measures that may require monitoring or maintenance), there may still be potential long-term risks associated with the release of pollution. Therefore, a significant environmental hazard can be considered abated under the statute even though potential long-term risks may not have been addressed and there remains an obligation to remediate the release.

Frequently Asked Questions About the Reporting of Certain Significant Environmental Hazards

Fact Sheet on Reporting of Certain Significant Environmental Hazards

Significant Environmental Hazards Quick Summary Table - A listing of Significant Environmental Hazards with their respective timeframes for notification and self-implementing initial response requirements [Please note: This table is for informational “at-a-glance” purposes, and the statute [CGS 22a-6u] should be consulted for specific wording and requirements of the law.]

For additional information on the Reporting of Significant Environmental Hazards, please contact the Remediation Division of the Bureau of Water Protection and Land Reuse at (860) 424-3705.

Content Last Updated April 30, 2021