Agriculture

The Agriculture collection includes general and agriculture-related maps and for photos illustrating a wide range of agricultural topics.
http://www.epa.gov/agriculture/maps.html

Great Lakes

The Great Lakes collection is an extensive collection of photographic images that provide a glimpse of the majesty of the lakes and their problems.
http://www.epa.gov/glnpo/visual.html

History

The History collection includes photographs of early EPA administrators, certain historic events, and the “Documerica” collection of photographs documenting subjects of environmental concern in the 1970s.
http://www.epa.gov/history/photos/index.htm

Non-road Diesel

The Non-road Diesel equipment collection includes photos of the many types of equipment covered by the Clean Air Nonroad Diesel Rule.
http://www.epa.gov/nonroad-diesel/photogallery.htm

USA.gov  

USA.gov links to U.S. Government Graphics and Photos (not necessarily environmental).
http://www.usa.gov/Topics/Graphics.shtml