Workers labored yesterday to remove fuel oil that spilled into a creek that winds through Fairfax County's Fort Belvoir military reservation and empties into the Potomac River.

An unknown quantity of diesel oil leaked late Saturday into Dogue Creek from an underground storage tank containing 5,000 gallons of fuel. The tank is just off the base and is owned by the U.S. Army Corps of Engineers' Humphreys Engineer Center off Telegraph Road.

The oil flowed from the center to the Fort Belvoir marina, about four miles, where it was confined with booms to a 25- to 30-yard stretch of the creek, and it was prevented from entering the Potomac River, according to Lt. Col. John E. Ooley of Fort Belvoir.

To remove the oil, workers were floating absorbent material on the surface, then skimming it off. Officials said it could take several days to absorb the oil from the creek.

"There is an odor, but you can't see anything in the water," said Ooley. "It's not what you think -- ducks with black oil all over them. As of yet, we don't know of any wildlife that's been affected, but we will be checking into that."

Ooley said the spill occurred when a newly installed underground tank containing 5,000 gallons of fuel became flooded with water from a ruptured main. Water entered the tank through a tank feeder pipe that had not yet been connected, he said. Some of the oil-water mix spilled out and seeped into the meandering creek.

Area residents noticed a strong fuel smell and alerted base officials at 10 p.m. Four hours later, a series of booms had been laid across the creek near the marina by the Fort Belvoir fire department, the Coast Guard and workers from Emergency Special Services, a private contracting company from Norfolk.

Spokesmen for the Humphreys Engineer Center, the Coast Guard and Emergency Special Services referred all calls to Ooley. Attempts to reach Environmental Protection Agency officials yesterday were unsuccessful, but Ooley said the incident was being handled by the military and that he doubted that charges would be filed.