STOCKTON, Calif. (AP) — A containment boom has been placed around a defunct 1950s-era cruise ship that began sinking and leaking pollution in California’s Sacramento-San Joaquin River Delta, authorities said.

The 294-foot (90-meter) ship permanently moored in Little Potato Slough northwest of the city of Stockton began to sink in 13 feet (4 meters) of water on Wednesday, the U.S. Coast Guard said in a statement.

A sheen was observed on the water, and containment booms were deployed around the vessel and the city’s water intake pump station, the Coast Guard said. Photographs show the stern low in the water next to the slough’s grassy embankment.

It was not immediately clear what was leaking. The Coast Guard said the vessel recently changed ownership so details about what pollutants were on board were unknown. The San Joaquin County Sheriff’s Office said the ship was leaking diesel fuel and oil.

A wildlife care organization was notified, but no oiled wildlife had been observed, the Coast Guard said.

The ship, currently known as the MV Aurora, was built in Germany in 1955 and formerly named Wappen von Hamburg. The ship moved around the world and ended up in the delta when a California man bought it in 2008 with dreams of restoring it as a shoreline attraction.