BANGOR — A system used to pump oily bilge water from U.S. Navy vessels is thought to be the cause of a spill, the sheen of which was visible from Bangor to the Hood Canal Bridge.

An estimated 2,000 gallons of bilge water spilled into the waters off Naval Base Kitsap — Bangor in the afternoon of Feb. 11, a Navy spokesman said. Department of Ecology officials said Feb. 12 there had been no signs that wildlife had been harmed.

The system pumps bilge water from vessels to a tank with a float on it, then into another tank; the bilge water ends up in a waste transfer station. On Feb. 11, the system did not sense the tanks were full and an overflow occurred, according to the Navy.

Though all piers at Bangor are boomed or double-boomed, the bilge water made its way out into open waters. The bilge water was 90-95 percent water, according to base public affairs officer Tom Danaher.

Danaher called the resulting sheen a “micro-sheen.”

According to early reports from the state Department of Ecology spokeswoman Joye Redfield-Wilder, the vessel was boomed but a tank on the deck was not — at least not entirely.

“In this case, some of the [bilge water] escaped. [That’s] how it was described to me yesterday,” she said.

Booms are placed at all piers at Bangor. However, booms do not guarantee complete containment, Redfield-Wilder said. The booms, she said, lessen damage done by spills and are a way to prevent, or help prevent a “catastrophic” event, she said.

The state Department of Health initiated a precautionary shellfish-harvest closure for Hood Canal. The Port Gamble S’Klallam Tribe initiated a geoduck and shellfish harvest closure in the bay and adjacent to the bay “until we assess what’s going on and assure it’s safe for everybody,” Port Gamble S’Klallam Chairman Jeromy Sullivan said Feb. 12.