Air & Waste Management Association
http://www.awma.org

American Chemistry Council
The American Chemistry Council represents companies engaged in the business of chemistry. The Council's goals include improved environmental, health and safety performance through Responsible Care, common sense advocacy designed to address major public policy issues, and health and environmental research and product testing.
http://www.americanchemistry.com/

American Water Works Association
http://www.awwa.org

National Association of Clean Water Agencies
http://www.amsa-cleanwater.org

State and Territorial Air Pollution Program Administrators / Association of Local Air Pollution Control Officials
The two national associations of state and local air pollution control agencies in the United States.
http://www.4cleanair.org/

Water Environment Federation
http://www.wef.org