MISSOULA, Mont.  — A Bush administration official appeared before a federal judge Tuesday, urging him not to hold the U.S. Forest Service in contempt over the use of a fire retardant that environmentalists say kills fish and plants.

Agriculture Undersecretary Mark Rey, who oversees the Forest Service, acknowledged the agency was slow in preparing environmental studies related to the effects of the chemical firefighting tool dropped from airplanes.

“There is no way to put a positive face on the fact that we dropped the ball,” Rey testified in court. “We’re sorry.”

While Rey was contrite, U.S. District Judge Donald W. Molloy was visibly frustrated by the delays. Molloy has threatened to hold the Forest Service in contempt, accusing the agency of skirting the law so it can keep fighting wildfires with the retardant.

“Don’t come in here on the last day — at the last minute — and tell me you’ve got a problem,” said Molloy, upset over the Forest Service’s failure to inform him of their difficulty in meeting deadlines.

If Molloy finds the agency in contempt, potential sanctions include sending Rey to jail, putting him under house arrest and banning the Forest Service from using any fire retardants but water in air tankers.

Rey, a former timber industry lobbyist who has directed U.S. forest policy since 2001, said the environmental studies were completed in good faith and that he did what he could to move them along.

Court recessed Tuesday afternoon without a ruling. Additional testimony was scheduled for today.

In 2005, Molloy ruled the Forest Service violated the Endangered Species Act and the National Environmental Policy Act when it failed to go through a public process to analyze the potential harm from using ammonium phosphate, a fertilizer that can kill fish, as the primary ingredient for fire retardant.

The ruling stemmed from a lawsuit brought by Forest Service Employees for Environmental Ethics after the group said fire retardant dropped in 2002 killed 20,000 fish in central Oregon.

Molloy said the Forest Service did not begin consulting with two key agencies, as required under the Endangered Species Act, until more than a year after the court ordered it to and just weeks before a deadline.

NOAA Fisheries, which oversees salmon protections, told the Forest Service last year that dropping poisonous fire retardant on wildfires was likely to jeopardize the survival of 26 species of salmon and other fish, and would destroy or harm critical habitat.

The Forest Service, after completing its studies in late 2007, said it had determined there was no significant impact from the use of the fire retardant and that species of concern could be protected through agency actions. Since then, the agency has said it’s collected additional information prepared by the U.S. Fish and Wildlife Service and the National Marine Fisheries Service and still believes there is no significant impact.

The plaintiff in the lawsuit said the Forest Service should be required to do more studies, including an environmental impact report that would be more extensive than the environmental assessment completed by the agency.

“All they’ve said is that you won’t jeopardize the continued survival of these species,” said Andy Stahl, executive director of Forest Service Employees for Environmental Ethics. “They might be clobbered, but they won’t go extinct.”