If the Moab uranium tailings pile stays where it is, eventually a big flood will wash it into the Colorado River.

"Not could. It will happen. It's just a matter of when," says one of the authors of a report on the subject, D. Kip Solomon, a University of Utah professor of geology and geophysics.

Even if no giant flood hits in the near future, radioactive and chemical contamination apparently has leached from it and migrated under the river. On the other side of the Colorado are a nature preserve and the city of Moab.

About 11.9 million tons of uranium tailings and contaminated soil were left near the Colorado River, three miles northwest of Moab, when Atlas Minerals Corp. stopped production in 1984. According to the U.S. Department of Energy, the wastes cover 130 acres and were placed in an unlined impoundment.

Atlas "placed an interim cover over the tailings pile in 1995," the DOE adds.

The department has been preparing an environmental impact statement about what to do with the tailings, which at the closest point reach to within about 1,000 feet of the river.

Gov. Jon Huntsman Jr. recently wrote to the DOE expressing his determination that the pile should be hauled away from the river as soon as possible.

"Recent flooding in the St. George and Santa Clara regions of Utah also demonstrated the swift and immense force of moving water in the desert," he wrote.

Huntsman's concerns are backed by studies, including one published in December 2003 by Solomon and Philip Gardner, a graduate student at the U.

DOE studies found ammonia and uranium in gravel below the Matheson Wetlands Preserve across the river, the researchers wrote.

"The magnitude of these concentrations and the location of the highest values suggest that groundwater from the mill tailings is flowing under the Colorado River and impacting groundwater" beneath the preserve, they added.

"We believe that there are fluids that have migrated underneath the river," Solomon said in a telephone interview.

Contrary to earlier expectations of the DOE, the river was not a barrier to the flow. A lot of contaminated fluids are discharging into the Colorado, he added. But some of it goes under the river to the Moab side.

Whether this occurs depends on the amount of water in the river and how much groundwater pumping is going on.

When the uranium mill was working, operators leached out material they needed by pouring fluids on the tailings. This caused material to leak out of the pile.

"They were pushing fluids beneath the river toward Moab," he said. Now that operations have ceased, whether the flow is still occurring "is a little uncertain."