RENO, Nev. (AP) - Citing growing concerns about health and safety, state regulators asked the U.S. Environmental Protection Agency on Friday to assume lead oversight over cleaning up radioactive and other toxic waste at a huge abandoned copper mine in northern Nevada.

Gov. Kenny Guinn wants EPA to take over regulatory control of the former Anaconda site at Yerington through a process similar to a Superfund designation, officials for the Nevada Division of Environmental Protection told The Associated Press.

The move, based partly on new concerns about the potential for groundwater contamination, "is the best way to protect human health and the environment," Guinn said in a brief statement Friday.

"We believe that designating a lead agency will make certain that the good work and ongoing progress at the site continues," he said.

Until now, the state had opposed changes in a 2002 agreement that gave state regulators, EPA and the Bureau of Land Management equal footing in the regulation of Atlantic Richfield Co.'s clean up of pollution at the site covering nearly six square miles in the irrigated high desert of Mason Valley, about 55 miles southeast of Reno.

But additional toxins documented in recent months - including uranium - and new concerns that the pollution may have seeped into water tapped by neighboring domestic wells prompted the request for EPA to replace the "memorandum of understanding" with a special designation under the Superfund law.

"It's like a Superfund designation but different. It puts EPA in charge of the site," NDEP spokeswoman Cindy Petterson said.

NDEP wants to continue as a coordinating agency in the clean up, she said. But "the need for a lead agency has been magnified by all the new data. There are some additional concerns about groundwater," she said.

Tests this summer found unusually high levels of radiation in soil samples at the mine. Earlier groundwater tests showed high concentrations of uranium in wells on site - up to 200 times the U.S. drinking water standard. Results of another round of testing of 100 wells this fall have yet to be made public.

"The need for a designated lead agency has been magnified by an evolving environmental understanding of the Yerington mine site," NDEP Administrator Leo Drozdoff said.

"Since the signing of the (memorandum), data has been collected that increases the degree of complexity surrounding the agencies' understanding of this project, particularly the ongoing discovery of the occurrence of multiple contaminant classes in multiple environmental media both on- and off-site," he said in a letter Friday to Wayne Nastri, EPA's regional administrator in San Francisco.

Drozdoff said Atlantic Richfield has been "very cooperative and responsive" in addressing concerns at the mine the past five years and he expects that to continue.

"We have always wanted to have something in place that is the most responsive to community needs," he said in explaining the proposed change in oversight.

"It's not like something was broken. We just know more. A lot more information has come in the door. Given that there still are questions and concerns about various environmental contamination, we think this is now the best approach," he told AP.

Dan Cummings, a spokesman for Atlantic Richfield's parent company, BP, said the company was "surprised and disappointed" by NDEP's decision.

"Atlantic Richfield has spent over $6 million in cleanup costs at the Yerington site," Cummings said.

"We only recently received approval for our work plans and have made good progress since that time," he said. He said the company has not received formal notification of any changes in oversight so doesn't know how they may affect future cleanup. The company already is providing bottled water to neighbors who want it.

Sen. Harry Reid, D-Nev., and leaders of the Great Basin Mine Watch are among those who have been pressing the state to allow EPA to make the mine a Superfund site. Drozdoff said NDEP still opposes that move but agrees "in the best interest of achieving overall progress at the site, it is time to change the management structure so as to provide for a lead agency."

Reid and environmental leaders said Friday they were pleased with the governor's request.

"It has become painfully clear that the state has not handled this cleanup appropriately, to the detriment of the local community and site workers," said Elyssa Rosen, executive director of the Great Basin Mine Watch in Reno.

Keith Takata, regional director of the EPA's Superfund program, said his agency probably would agree to take the lead in the cleanup.

"In general we support the state's request and are likely to agree to it," Takata said. "We agree with the state and other parties that things at the site haven't been progressing as quickly as they could."

Guinn is asking EPA to assume primary responsibility for oversight as part of a "Section 106 designation" under the main Superfund law - the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA).

The move is backed by Lyon County, the city of Yerington and the Yerington Paiute Tribe, NDEP said.

It differs from the usual Superfund process in terms of who pays for cleanup. With a Superfund designation, EPA can clean up sites using Superfund money, then sue potentially responsible parties for reimbursement.

The state's request to EPA comes a month after a former federal manager of the site said he was fired for refusing to keep silent about dangers posed by radioactive and other toxic wastes at the mine.

NDEP mine site: http://ndep.nv.gov/yerington/minesite.htm

U.S. Bureau of Land Management in Nevada: http://www.nv.blm.gov/

Great Basin Mine Watch: http://greatbasinminewatch.org