COEUR d'ALENE - The Idaho Transportation Department has been quick to contain a small oil leak this month from a piece of machinery the agency accidentally slid into Lake Coeur d'Alene 20 years ago.

"There's not been any effect that we've been able to see. Mostly aesthetics at the worst," said Kreg Beck, site remediation manager for the Idaho Department of Environmental Quality, which is overseeing the other agency's work. "ITD has been very cooperative in responding to the release."

The transportation department received a report a few weeks ago of a slight sheen of oil off Higgens Point, where a D9 dozer fell in during Interstate 90 construction in 1990.

An ITD diver confirmed the construction equipment was leaking fuel.

"It was undoubtedly an accident that occurred," said Barbara Babic, ITD spokeswoman.

The dozer, as well as a 631 CAT Scraper, had slid into the east side of the lake while crews were laying fill for an interchange. The operators miraculously survived, Babic said, but the two pieces of machinery were buried in 200,000 cubic yards of fill material, complicating the procedure to lift them out.

Regulatory agencies agreed it was better to leave them at the bottom of the lake than risk tearing up the lake bed and the spawning area there.

The equipment lay dormant until 2000, when the dozer began leaking, she said.

ITD installed a permanent collector system to contain released materials.

"That's been working just fine," Babic said. "In recent years, very little if any oil or gas has been leaking."

Except for this month. The agency discovered the leak collector had become dislodged, possibly due to a snag from a boat anchor.

Repairs began immediately, Babic said, and in the meantime a boom has been placed on the spot to catch any more fuel.

"We'll also be making improvements, upgrading it. Technology changes and there are better collector systems," Babic said.

The repairs might take a few more weeks, she said.

Beck said it's difficult to judge how much was leaked, but he's convinced it wasn't a dangerous amount.

"It's not enough to affect anything environmentally that we've noticed," he said. "Especially at the rate it's coming out. The release has slowed considerably after that first week or two."

He isn't surprised the equipment is still leaking, he added.

"We always felt like it would probably be intermittent," he said. "A lot of leaking depends on how that machinery is weathering and rusting, and the lake bottom conditions changing."

The collector system is adequate for containing leaks, he said, and he's confident ITD is on top of it.

"They do what's necessary to keep it under control when it (a leak) does show up," he said.

ITD monitors the equipment annually with a diving check, Babic said, and staff conducts intermittent visual checks, as well.

The DEQ will also be keeping an eye out, Beck said.

"It will be something we'll be checking on, and if things change, we'll react to it," he said.