A second major kerosene spill that went undetected for almost 24 hours while Virginia and federal officials fought a larger rupture on the same oil pipeline in Manassas now threatens the fresh water supply of Fredericksburg, federal officials disclosed yesterday.

Virginia game wardens, worried that wildlife may be threatened, began moving beaver to safety and said bald eagles and other fowl could be adversely affected by kerosene-polluted water in both areas.

Fredericksburg city officials used radio broadcasts to urge residents to use as little water as possible as a 31-mile-long slick approached the city's fresh water inlet on the Rappahannock River.

An Environmental Protection Agency spokesman said there is no immediate danger to the Occoquan Reservoir in southern Fairfax County, which supplies drinking water to 660,000 Northern Virginians, nor to the Fredericksburg area.

But he said the spills are "a major pollution incident with potentially devastating effects on fish, wildlife and the environments of both areas."

The spokesman called the two leaks the largest fresh water oil spill in Virginia's history.

Colonial Pipeline Co. spokesman Jim Sorrow said the second repture, along the 32-inch-diameter underground system that is a major Petroleum transmission route from Texas to New Jersey, dumped about 60,000 gallons of aviation kerosene southeast of Culpeper, 34 miles south of the first spill.

That brought the combined size of the two spills to an estimated 310,000 gallons.

The cause of Thursday's pipeline failures was still unknown yesterday.

Sorrow said an "unscheduled shutdown" of equipment at the company's booster station in Conowingo, Md., northeast of Baltimore, significantly raised the pressure in the pipeline.

Colonial's Atlanta control center said the situation was aggravated when a smaller conduit also failed to operate, blocking efforts to divert kerosene into a Fairfax terminal near the Manassas break.

An Atlanta controller also "failed to react" by adjusting equipment that would have substantially reduced the pressure, the company said.

"The pressure at both points was within Transportation Department limits and below the limit by which the pipeline had been tested," Sorrow said. "We simply had no idea there were two spills. We discovered one and figured it was the only break.

EPA spokesman George V. Bochanski Jr. said the second spill moved into Mine Run, then into the Rapidan River and eventually to the Rappahannock River. The Rappahannock supplies drinking water to 55,000 people in the Fredericksburg area.

State game wardens in the Occoquan watershed reported they were moving an unspecified number of beaver from the Bull Run area when the highly toxic and foul-smelling kerosene began clinging to the animals' fur. Bald eagle nesting areas south of the massive 10 billion-gallon reservoir could also be threatened, Bochanski said.

Game wardens on the Rapidan River said they were forced to kill three ducks who were "deathly ill" from drinking the water. Rappahannock River fishermen said that fish had submerged to depths far below their lines to avoid the creeping kerosene slicks.

"The next 24 to 48 hours will be crucial in determining the effect on the wildlife," Bouchanski said, "and we are not at all optimistic on what we will find."

Federal officials have quickly assembled a small army of "top cadre environmentalists and oil spill experts" at both sites from the U.S. Coast Guard, the Army Corps of Engineers, the Interior Department's Fish and Wildlife Service, The federal Emergency Management Agency, the state Water Quality Control Board, and the Health, Education and Welfare Department.

"It's really an environmental response team," said Ken Biglane, director of EPA's oil inspection and materials control division, who has fought oil spills from Buzzard's Bay, Mass., to Corpus Christi, Tex., for the last 18 years.

"The initial task is to mitigate the damage to water resources and to wildlife," Biglane said.

Peter R. Kolakowski, Fredericksburg's assistant city manager, said the city's fresh water canal inlet on the Rappahannock has been closed and that a 10 million-gallon storage pond, as well as water supplied by Stafford and Spotsylvania counties, "will give us about four days to get this cleaned up."

But an apparent leak below the water surface in the lock wall threatened to allow the kerosene, which is "moderately soluble" in water, into the canal, Bochanski said.

Tom Massey, EPA's on-site coordinator at the Occoquan spill, said 20,000 gallons have been recovered since the spill occurred. He addd that "20 percent of the kerosene will evaporate. About 40 percent of the total spill will be recovered, and that will leave up to 40 percent that may get into the reservoir."

Environmental officials said they are optimistic that kerosene concentrations will not approach 180 parts per billion at either site, which would make the water unfit to drink. The slick was still about seven miles from the Occoquan Reservoir yesterday.

The Rappahannock spill apparently originated near Rte. 645 in Orange County, Kolakowski said. Private oil recovery crews and EPA workers installed flotation collars a mile upstream from the Fredericksburg canal locks, and a deflection boom was stationed near the canal, Bochanski said.

Bochanski said there will be a federal investigation into both spills, but not before initial recovery and wildlife preservation efforts are complete.

"The situation is much better in the Occoquan where they have access to activated carbon to clean the water," Bochanski said. "They don't have that at Fredericksburg where they must add the carbon manually, which is less effective. We're taking samples from both stations periodically to determine the concentration."

"As long as it doesn't rain anymore," Massey said, "we could be in good shape."