The oil, which might have leaked out overnight, came from a catamaran called the Overbudget, which is moored at the Dock Street Marina, 1816 Dock St., said Kim Schmanke, a state Department of Ecology spokeswoman.

The spill was reported to Ecology Department officials at 6:46 a.m. by the Tacoma Fire Department. Firefighters floated 800 feet of containment boom in a attempt to capture the oil, she said.

“There’s a visible sheen on the water,” Curt Hart, a state Department of Ecology spokesman, said Monday morning.

It’s unclear exactly what led to the spill, but Hart said officials suspect diesel contaminated the bilge tank of the Overbudget. When the bilge pump emptied the tank, the diesel spilled into the waterway, Hart said.

Schmanke said the owner of the Overbudget, whose name is Mike Hathaway, hired NRC Environmental Services, a cleanup company, to mop up the spilled fuel.

Hathaway, a Tacoma resident, said he reported the spill Monday morning when he dropped by the marina to check on the boat. He blamed the leak on a faulty fuel filter in the engine. Although nothing was amiss Sunday afternoon when he took out the boat, others at the marina noticed something wrong about 7 p.m. Sunday, but failed to report it, Hathaway said.

He estimated that the cost of cleanup and repair would amount to between $2,000 and $5,000.

Besides the Ecology Department and Tacoma firefighters, the U.S. Coast Guard and Tacoma Public Works Department officials also responded to the spill, authorities said.

Although the spill did not exceed 100 gallons, Hart did not discount its affect. “Oil is an environmental toxin,” he said. “This just adds to the toxic load already in the water.” According to Schmanke, a quart of oil could foul more than 100,000 gallons of water.

Susan Gordon: 253-597-8756