Dave Connor, operations coordinator of ballast water treatme

UNITED STATES - AUGUST 15: Dave Connor, operations coordinator of ballast water treatment, walks between two dissolved air flotation (DAF) tanks on the grounds of the Alyeska Pipeline Service Company Valdez Marine Terminal in Valdez, Alaska Monday, August 15, 2005. Tankers take sea water into their ballast tanks while traveling without a load of crude oil to ensure proper operation of the tanker at sea. Once the tanker is berthed at port, the water is discharged and treated to remove residual oil from the sea water. The recovered oil is returned to a ship and the water is treated further before being pumped back into the Port. (Photo by Daniel Acker/Bloomberg via Getty Images)