Susan Bush, who is director of the Lexington's Division of Environmental Policy, was named acting commissioner of the Department of Environmental Quality by Mayor Jim Newberry on Thursday.
The appointment, subject to confirmation by the Urban county Council, takes effect Monday.
Cheryl Taylor, who held the post, has taken a job with Kentucky American Water.
Newberry noted that Bush came to the city two years ago with 30 years of experience in environmental issues and public policy.
In her role as acting commissioner, Bush's largest task will be overseeing compliance with the city's agreement with the Environmental Protection Agency to improve its sanitary and storm sewer systems.