Environmental Health Workforce Act of 2017 This bill requires the Department of Health and Human Services (HHS) to develop model standards and guidelines for credentialing environmental health workers. HHS must develop a comprehensive and coordinated plan for the environmental health workforce that includes performance measures and identifies: (1) any gaps between existing programs and future environmental health workforce needs, (2) actions needed to address any identified gaps, and (3) any additional statutory authority required by HHS to implement identified actions. The Government Accountability Office must identify best practices related to training and credentialing environmental health professionals in six states, based on the examination of three states that have credentialing requirements for environmental health workers and three that do not. The bill also amends the Higher Education Act of 1965 to specify that environmental health workers are eligible for public service loan forgiveness.