The Department of Interior is responsible for managing and conserving federal land and resources across the US, as well as programs relating to indigenous people. 

The department’s agencies, which are covered by FOIA, include the National Park Surface, Bureau of Indian Affairs, Bureau of Ocean Energy Management and more.

On its website it describes itself as: “The U.S. Department of the Interior is a Cabinet-level agency that manages America’s vast natural and cultural resources. Secretary of Interior Sally Jewell heads our department, which employs 70,000 people, including expert scientists and resource-management professionals, in nine technical bureaus and various offices.”

The spreadsheet with contact details can be accessed and downloaded here.