ExxonMobil has finished cleaning four sites contaminated by crude oil along the Yellowstone River and government regulators now will now ensure the sites have been cleaned to federal and state standards.

These sites -- just east of the spill site in Laurel -- are the first to be completed since an ExxonMobil pipeline ruptured and dumped an estimated 42,000 gallons of medium crude oil into the Yellowstone River three weeks ago.

The Environmental Protection Agency along with the Montana Department of Environmental Quality will now go in and assess the cleanup effort, checking to see that oil has been removed to their satisfaction.

"Montana standards (for cleanup) are more stringent than EPA's," said Craig Myers, the EPA on-scene coordinator for the spill.

Tom Livers, deputy director for Montana DEQ, said state standards dictate that cleanup continue until the effort would do more harm than benefit to the long-term health of the environment.

"It's not always a clear, bright line," Livers said.

In all, 46 sites were initially identified for cleanup. As teams continue to work down the shoreline of the river, the number of sites could change, officials said.

Pompeys Pillar National Monument  -- a rock formation along the Yellowstone that bears the etched signature of William Clark of the Lewis and Clark Expedition -- is clean of oil and open for the 2011 Clark Days festival, which begins Saturday.

"No oil has been found at the monument," said Jim Sparks, field manager of the Bureau of Land Management's Billings office.  "It's safe for visit and use."

Soil, air and water samples from around the monument have come back to the BLM showing no levels of contamination.

The furthest confirmed sighting of oil was reported 72 miles from the spill site.

Wildlife experts have cleaned and released the oiled Cooper's hawk captured earlier this week.

International Bird Rescue out of California was brought in by Exxon to clean wildlife affected by the spill. So far, workers have only had to treat three birds.

"We're pretty happy that there's not a lot of birds here," said Jay Holcomb with International Bird Rescue.

Crews cleaned a goose earlier in the week, which they're still holding until it's strong enough to release back into the wild.

Biologists also are monitoring a bald eagle that has oil on its tail feathers. If it appears the oil is impeding its ability to hunt, nest and keep itself warm, biologists will capture it and bring it in for cleaning.

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Contact Rob Rogers at rrogers@billingsgazette.com or 657-1231.