A ship company based in Germany and the chief engineer on one of its vessels have agreed to plead guilty to illegally dumping oily water off Alaska.

Federal prosecutors announced Thursday that AML Ship Management GMBH and Nicolas Sassin, the chief engineer on the AML-operated ship City of Tokyo, agreed to plead guilty to violating federal clean water law by knowingly dumping 4,500 gallons of oily bilge water south of the Aleutian Islands.

The company and Sassin, 45, face a separate charge of presenting false pollution oversight records to the U.S. Coast Guard when the vessel docked in Portland, Oregon, prosecutors said.

As part of the plea deal, AML agreed to pay $800,000 in fines and community service payments.

Prosecutors are recommending a six-month jail sentence for Sassin, to run concurrent with any jail time imposed from a conviction in the Oregon case.

An email seeking comment was sent to AML's headquarters. Sassin is represented by a Seattle attorney, Irwin Schwartz, who was not in his office after business hours Thursday.

Discharge of oily waste from vessels is a worldwide problem, said Kevin Feldis, first assistant U.S. attorney.

"This is the first time we have charged Clean Water Act crimes for an actual discharge of oil into the EEZ (exclusive economic zone) off the coast of Alaska," Feldis said in an email. "As detailed in the court documents, witnesses saw a sheen off the side of the vessel after the chief engineer hooked up a pump to illegally dump oily bilge water overboard."

Water routinely accumulates in the bilge, or bottom, of vessels. Federal law requires ships to store it until it can be treated on shore, or to run it through an onboard oil-water separator. Water that contains less than 15 parts per million of petroleum can be dumped overboard.

The City of Tokyo had departed South Korea on Aug. 22 to go to Seattle; Tacoma, Washington; and Portland.

On Aug. 29, as the ship passed 165 miles south of Alaska's Sanak Island, Sassin used an illegal pump system to dump untreated oily bilge water over the side of the 603-foot ship, bypassing the oil-water separator and other pollution control equipment, prosecutors said.

"Nobody knows exactly how much oily waste is illegally dumped from ships, but as this case demonstrates, a determined engineer with a few pieces of equipment who does not have proper oversight can easily circumvent the pollution prevention equipment onboard vessels," Feldis said.