PORT GAMBLE — While the recovery efforts have wrapped up following Monday’s diesel oil spill in Gamble Bay, the investigation as to what happened is still ongoing.

The U.S. Coast Guard had finished its recovery efforts by Thursday, said Coast Guard spokesman Adam Eggers.

The Guard’s contracted clean-up team, NRC Environmental Services, absorbed as much oil as it could recover; the remaining fuel in and around Gamble Bay will eventually evaporate, Eggers said.

Officials now estimate as much as 200 gallons of red marine diesel fuel leaked from the tugboat that had sunk into Gamble Bay, next to one of the piers at the old Port Gamble mill site. Initial reports Monday put the amount of fuel spilled at 100 gallons.

Divers were able to plug the leak Tuesday on the vessel identified as the source of the leak. Active, the 91-foot sunken tug boat, is believed to have sunk sometime late Sunday night or early Monday morning.

The investigation as to why the leak occurred and how the tugboat went under is ongoing, Eggers said. The boat’s owner has been identified as Thomas Lampman, but no additional information about the investigation has been released.

The Washington State Department of Health had asked local tribes to delay geoduck harvesting for a day, however, information from responders indicated that geoduck beds were not affected and harvesting could resume. Even so, the Kitsap County Health District has released an advisory to the public to not harvest or eat shellfish from Gamble Bay until further notice.

U.S. Congressman Jay Inslee (D-Bainbridge Island) addressed the issue of improving spill response processes in a letter to members on the House Committee on Transportation and Infrastructure Tuesday. He urged the committee to implement recommendations made following the 4,700-gallon spill near Edmonds that took place in December 2003. That spill affected a pristine wetland area in Indianola. He also encouraged the committee to commission an independent investigation on ways of improving the spill response process.

“(Monday) marked yet another oil spill to hit Puget Sound in less than two years,” Inslee said, referring to this week’s spill, an estimated 100-gallon oil spill last year in the Dalco Passage, near Tacoma, and December 2003 incident. “We can do a better job preventing and responding to spills here and across the nation.”

In Dalco Passage, heavy-grade fuel oil spilled during the early morning hours of Oct. 14, 2004, before being reported. The response to the major spill at Point Wells was delayed by at least 30 minutes because the vessels dispatched to lay the initial containment boom wouldn’t start.

While Caicos Corporation had put its spill response efforts into place Monday morning, the Coast Guard’s spill response contractor didn’t arrive on the scene until around 3 p.m. Monday.