Some of the text, images, or videos on this site are based upon work from other authors. In some cases the authors are explicitly referenced. In all other cases the authors graciously licensed their work with either a public domain license or the creative commons share-alike license.

creative commons CC-BY-SA

The full list:

  1.×435.jpg. CC-BY-SA-3. Original photo by Gary D. Robson. Unedited.
  2.×435.jpg. CC0 Public Domain. Free for commercial use. No attribution required. Unedited.
  3.×435.jpg. CC-BY-SA-2. Originally uploaded to Original photo by Keven Law. Photo cropped.
  4.×435.jpg. Original photo from catalog. Public domain, provided by the Library of Congress. Unedited.
  5. Photo from CC0 Public Domain. Unedited.
  6. Photo from CC0 Public Domain. Unedited.
  7. PNG from CC0 Public Domain. Cropped.
  8. Photo from Pixabay. CC0 Public Domain. Unedited.
  9. Photo by Ammodramus. CC0 Public Domain. Unedited.
  10.×435.jpg. Source: USDA NRCS Photo Gallery. As a work of the US Government, it is considered Public Domain in America. Unedited.
  11. Source: Eutrophication&Hypoxia: Unedited photo. CC-BY-2.0
  12. Unedited photo. GFDL 1.2 by Polimerek. Unedited.
  13.×435.jpg. GFDL 1.2 by Weihao.Chiu Unedited.
  14. Source: USDA NRCS Photo Gallery. As a work of the US Government, it is considered Public Domain. Photographer name: unknown. Unedited.
  15. CC-BY-SA-2.5. Original photo by Unedited.
  16. Original photo by David Hiser. Photo taken while David Hiser was working for the government. Now stored in the national archives NARA record 3651517, ARC identifier 545634. Unedited.
  17. Photo by Joshua Doubek, Cropped. CC-BY-SA 3.0.
  18.×435.jpg. Original photo by CC0 Public Domain. Unedited.
  19. “Nandu River Iron Bridge,” Nandu River, Hainan, China. Original photo by Anna Frodesiak, CC0 1.0 Public Domain. Unchanged.
  20. Concrete Corrosion Crack. Original photo by Amit Kenny, Public Domain. Unchanged.
  21. Corrosion of Aluminum. Original photo by Carlos Delgado, CC-BY-SA-4.0. Unchanged.
  22. Dairy Wastewater Management Lagoon in eastern Louisiana.  Original photo by Bob Nichols, courtesy of USDA NRCS. Unedited.
  23.×435.jpg. Taskila Wastewater Treatment Plant in Oulu. Original photo by Estormiz CC0 Public Domain. Unedited.
  24. CSIRO ScienceImage, Wastewater pit from a Mine. Photo courtesy of CSIRO CC-BY-3.0. Unedited.