New Study of Colorado River Flooding Released

Scientists have just revealed a new study showing higher volume and frequency of extreme floods along the Colorado River. The new study shows Utah's uranium waste pile at Moab is at risk while funding for removal of the radioactive waste stalls in Congress.

In an effort to better understand the impacts from extreme floods on the infrastructure and water resources of the Colorado River corridor, Living Rivers, supported by a grant from the Citizens' Monitoring and Technical Assessment Fund, commissioned two flood studies in Utah near the town of Moab.

Two critical issues were examined:
1) River migration adjacent to the second largest uranium waste pile in the United States
2) The magnitude and frequency of large floods along the Colorado River

These investigations were performed by two professors of geology from the University of Arizona: John C. Dohrenwend and Noam Greenbaum. Victor Baker, a pioneer in the field of flood research, reviewed their findings.

The report on river migration by Dohrenwend emphasized how previously contracted investigations by the Department of Energy (DOE) failed to provide reasonable assurances that this radioactive waste pile in Utah was safe from probable maximum floods within the next 1,000 years, a reclamation standard the DOE is required to fulfill under Environmental Protection Agency regulations.

Dohrenwend also announced to the DOE that a paleoflood study would help to remove the uncertainty, and that a professional investigation would be conducted. Paleoflood studies are detailed examinations of flood sediments and organic deposits--the remnants of huge floods that once tumbled down the Colorado River before modern-day instruments began to measure stream flow. This was to be the first study of its kind for the Colorado River upstream of Arizona.

The results of the paleoflood study were completed in June 2006 by Greenbaum, who provided physical evidence to support a conclusion that floods occurring at 100- and 500-year intervals in the Colorado River Basin are not yet properly understood.

It is generally accepted by resource managers that a 100-year flood on the Colorado River has a peak discharge of about 100,000 cubic feet per second (cfs), and that a 500-year flood has a peak discharge of about 120,000 cfs. The limit of a maximum flood is considered to have a peak discharge of 300,000 cfs and occurs around intervals of 10,000 years.

Greenbaum's preliminary findings indicate that these conventional flood estimates are vastly underestimated by a factor of five times. His data shows that over the past 2000 years, at least 20 floods have matched or exceeded the 500-year estimate, and that five probable maximum floods have also occurred in the same time period. Greenbaum also discovered the possibility that two floods may have exceeded 350,000 cfs.

Says Greenbaum, "This study shows that catastrophic floods can occur with much greater frequency than originally speculated, and such floods could happen, quite frankly, sooner as opposed to later." "Such floods are induced by springtime storms that drop warm rain on mountainous snow packs," added Victor Baker from Tucson.

The scientists recommend additional investigation be undertaken to better understand the potential for severe flooding along the Colorado River above Glen Canyon Dam.

"These preliminary results of high magnitude floods occurring at greater frequencies spotlight future vulnerabilities for the entire Colorado River watershed," says John Weisheit, conservation director of Living Rivers. "This paleoflood study provides useful information for all resource managers of the Colorado River, so that they can take action to reduce the hazards associated with catastrophic floods."

The findings of Dohrenwend and Greenbaum are contained in the recently published report by Living Rivers, The Moab Mill Project: A technical report towards reclaiming uranium mill tailings along the Colorado River in Grand County, Utah.

The 36-page color report (with additional photos and drawings) is available for download at:
Moab Mill Project [4m PDF File]

Printed copies are also available from: Living Rivers PO Box 466 Moab, UT 84532

Supplemental information

Two years ago it seemed likely that the uranium waste pile (the former Atlas Corporation uranium processing facility) along the Colorado River near Moab, Utah, would remain in place with nothing to protect it from large flood events other than a veneer of clay and large rocks.

Instead, the Department of Energy (DOE), the agency designated by Congress in 2000 to reclaim the site and remediate the groundwater, issued a Record of Decision in 2005 announcing that the pile would be moved 30 miles to the north and out of harm's way.

The Colorado River supplies water for metropolitan areas such as Phoenix, Las Vegas, Los Angeles, and San Diego, as well as much of the region's agricultural industry. Other river resources at risk of radioactive contamination include the riverine ecosystems of national parks, such as Grand Canyon and Canyonlands.

On July 17, at a public meeting in Moab, it was disclosed that DOE's funding cycle for the next five-years will be insufficient to remove the pile as scheduled. Instead, DOE documents reveal that continuing site remediation and incremental preparatory work is anticipated, until which time a committed appropriation for removal by Congress is approved.

Since taking over responsibility of the pile in October of 2001, the DOE and the project contractors have expended in excess of $23.5 million at the end of the first quarter for year 2006. For the next five years, it is projected they will spend about $136 million, with no financial guarantee that the next five-year cycle will mean the actual removal of the pile.

For additional information, contact: John Weisheit 435-259-1063 Cell: 435-260-2590 Sarah Fields: 435-259-4743

Department of Energy: Moab Project
City of Moab and Grand County Council