An official website of the United States government.

We've made some changes to If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

AQS User Support

AQS User Support is provided through the EPA Enterprise IT Service Desk (EISD), which is operated under contract to the EPA.
The toll free number is 1-866-411-4EPA - (4372), select option 9. TDD: 1-866-489-4900, International callers: 1-703-679-1070
Their hours of operation are 6:00am - 9:00pm E.T. (Monday - Friday, excluding Federal holidays).  You may also contact the Call Center via email   ( or fax (703-674-1008).

The Exchange Network Services Center (ENSC) is EPA's electronic reporting site. ENSC support is available toll-free between the hours of 8:00 am and 6:00 pm (EST) at 888-890-1995 - choose option 2 for Node Helpdesk Supportor via email at

New EPA IT Password Security Policies.

Contact a Regional EPA representative or a State, Local, or Tribal Agency representative.

You may need a PDF reader to view some of the files on this page. See EPA’s About PDF page to learn more.