The Montana State Board of Health was established in 1901. In 1967 the Legislative Assembly created the State Department of Health. The State Board of Health continued in an advisory capacity, but the day-to-day administration of the state laws regarded public health and related matters were relegated to the new department. The State Board of Health became The Department of Health and Environmental Sciences in 1971 with the passage of Governor Anderson’s Executive Reorganization Order 9-71. In 1991, though it remained a part of the Department of Health and Environmental Sciences, the role of the Environmental Sciences Division was considerably expanded to include: Natural Resource Damage Assessment, a Petroleum Tank Release Compensation Board, a Superfund Section, and an Underground Storage Tanks Section.

The Environmental Sciences Division eventually became its own separate department, renamed the Department of Environmental Quality, in 1995, comprised of the following divisions: Director’s Office, Air Quality, Centralized Services, Energy, Environmental Remediation, Reclamation, Waste Management, and Water Quality.

The public health-related functions of DHES meanwhile fell under the umbrella of a new agency, The Department of Public Health and Human Services (DPHHS), which, at the time of its creation, was comprised of the following divisions: Child and Family Services, Child Support Enforcement, Disability Services, Health Policy and Services, Mental and Addictive Disorders, Operations and Technology, Quality Assurance, and Senior Support Services.

The DHES Director’s Office was, and is, responsible for administering the various programs overseen by the agency, and drafting and enforcing appropriate policies and procedures throughout all organizational units of the agency.