William “Bill” Shepherd, an environmental specialist with Marine Corps Air Station Yuma, Ariz. environmental section, performs his duties on Oct. 16, 2017. Shepherd is in charge of making sure everyone on station has safe drinking water and it is environmentally safe. He will retire on Oct. 19, 2017 after faithfully serving the U.S. government for 32 years. (U.S. Marine Corps photo by Lance Cpl. Sabrina Candiaflores) - William “Bill” Shepherd, an environmental specialist with Marine Corps Air Station Yuma, Ariz. environmental section, performs his duties on Oct. 16, 2017. Shepherd is in charge of making sure everyone on station has safe drinking water and it is environmentally safe. He will retire on Oct. 19, 2017 after faithfully serving the U.S. government for 32 years. (U.S. Marine Corps photo by Lance Cpl. Sabrina Candiaflores)