The Environmental Council of the States (ECOS) is the national nonprofit, nonpartisan association of state and territorial environmental agency leaders. The purpose of ECOS is to improve the capability of state environmental agencies and their leaders to protect and improve human health and the environment of the United States of America.
ECOS was established in December 1993 at a meeting of approximately 20 states in Phoenix, Arizona. A 501(c)(6) organization, ECOS relies on dues from its members as well as federal and private sources of funding.