20110705 yellowstonefalls 54
View of the Lower Falls at the Yellowstone Grand Canyon in the Yellowstone National Park, Wyo., on June 2, 2011. - 

Jeremy Hobson: Well now to Montana and that Exxon pipeline that spilled a thousand barrels of crude into the Yellowstone River last Friday. Officials are now saying Exxon will have to bury the pipeline deeper than five to eight feet under the riverbed to prevent future spills. And the whole episode is bringing the issue of pipeline safety to the surface.

From the Marketplace Sustainability Desk, Eve Troeh reports.

Eve Troeh: Pipeline spills are different than offshore oil spills. The Department of Transportation oversees pipelines. It requires a worst case safety plan for each one. But:

Richard Kuprewicz: All the dry runs or drills in the world aren't going to be really effective if they don't apply to the case that you actually experience.

Richard Kuprewicz consults energy companies on risk. He says Exxon seems not to have accounted for heavy, late spring snow in Montana. That's now melting, and has the Yellowstone River rushing and flooding its banks.

Kuprewicz: We're finding too many incidences where the oil spill response plans are not really effective because they didn't really address a worst case scenario.

Prevention should be the focus, says Mike Levine at the nonprofit Oceana. Even the best cleanup plan won't get out all the crude.

Mike Levine: We simply can't. There's going to be a lot of oil left in the ocean or in the river.

Likely 90 percent of what's spilled, he says. Exxon shut down the pipeline in May, over fears a fast current could damage it, but then decided the risk wasn't that high.

I'm Eve Troeh for Marketplace.

Follow Eve Troeh at @evetroeh