Federal engineers in an agency responsible for safeguarding the ocean environment “intentionally and repeatedly” dumped oily, dirty water into the ocean, then claimed they were exempt from the law, according to a federal watchdog.

National Oceanic and Atmospheric Administration employees dumped untreated bilge water from a ship’s bilge into the ocean roughly every six days throughout 2013, violating environmental laws, federal regulations and the agency’s own policies, the Department of Commerce Office of Inspector General found. They also spilled fuel in a harbor.

Bilge water can contain oil, urine, detergents, chemical solvents and foreign fish species that are hostile to those in the locale in which it is dumped, causing damage to the environment and wildlife. Government strictly regulates how, when and where ships coming into U.S. ports dump bilge water.

The IG criticized the ship’s “culture that discouraged environmental compliance efforts” and noted “a general lack of oversight concerning engineering operations by several NOAA Commissioned Officer Corps on this ship.”