RENO, Nev. (AP) - Test results the U.S. Environmental Protection Agency has cited repeatedly as evidence that irrigated crops and livestock next to a polluted Nevada mine are safe for consumption were based on samples from four onions taken more than four years ago, newly disclosed documents show.
As recently as December, EPA referred to the tests conducted in 2007 to address concerns raised by a neighboring tribe and others about elevated levels of uranium and arsenic identified in irrigation wells used historically for alfalfa and onions north of the old Anaconda Copper Mine. The site is near Yerington, about 65 miles southeast of Reno.
The disclosure of the tiny sample has further riled leaders of the Yerington Paiute Tribe, who say that mischaracterization of the tests by the EPA undermines assurances from the agency that crops are safe to eat in the Mason Valley - an irrigated oasis in Nevada's high desert where only 5 inches of precipitation falls annually.
"They say the agriculture is safe but they don't have data to support that," said Linda L. Howard, the chairman of the tribe, who is pressing the agency to conduct a comprehensive study of potential threats to area agriculture created by the World War II-era mine.
"EPA seems to be depending on a one-time check of a few onions from one farmer's field," she said. "With a large number of heavy metals and radioactive materials released from the site, we would hope a responsible EPA would look a bit farther into the problem."
EPA project manager Jere Johnson issued a statement Dec. 21 in response to the tribe's complaints the agency isn't doing enough to pinpoint the current location of the toxic plume from the mine and its potential impact on water drawn for irrigation.
"Crops grown and livestock raised in the vicinity of the mine should be considered safe for consumption," Johnson said. She went on to largely repeat EPA's statement in the March 2011 edition of its monthly Anaconda/Yerington Mine newsletter regarding the 2007 onion test.
The onions were "selected from random areas" in an irrigated field just north of the site boundary where Yerington-based Peri & Sons Farms operates its Desert Pearl Farms. Not only did the test results show low levels of uranium concentration, they were below levels typically found naturally in onions in most places in the United States, she said.
"Accordingly, EPA concluded that the test results showed that the Anaconda mine did not elevate uranium levels in local onions," Johnson said.
Howard said in a letter to EPA's regional administrator earlier this month that the agency's assurance about crop safety "far exceeds the intent and scope of that small study" of the Peri onions. She told The Associated Press the tribe will ask the EPA about "withdrawing or otherwise correcting that statement so that it is consistent with the facts, or in this case the lack of data, about the site."
Tribal members, other neighboring residents and environmentalists who want the site added to the EPA's Superfund National Priority List are in conflict with local politicians and agricultural interests who say the critics are exaggerating the health and safety risks at the expense of the area economy.
"The tribe apparently wishes to suggest through innuendo and false statements that there is a threat to agriculture with the apparent belief that such a campaign will advance whatever agenda it may have," said Brad Johnston, general counsel for Peri & Sons Farms.
"The results of this initial testing also made clear that additional testing was not needed and the tribe's suggestions to the contrary are unfounded," Johnston said.
The onion study itself is among thousands of pages of documents entered in the formal cleanup record since the EPA became involved in the 1990s. But the data doesn't appear on the agency's Yerington web site and details of the survey hadn't been disclosed until tribal sources found the study and provided the AP with a copy.
The EPA confirmed the authenticity of the report, which shows contractor CH2M Hill sampled the onions in September 2007 but did not finalize the results until early 2009.
The four onions were collected within about 2,500 feet of each other, and the contractor made it clear to the EPA the sample wasn't large enough to draw scientific conclusions.
"The technical approach to onion sampling was not meant to be a standard, statistically-defensible approach, but instead a limited, initial random sampling to gauge whether a more thorough investigation would be warranted," CH2M Hill said in its final technical memo to the EPA.
The mine's neighbors didn't learn until about eight years ago that Anaconda officials had known as early as the 1970s that a toxic stew was brewing beneath the mine as a result of uranium and other chemicals leaking through leach ponds where the copper was processed.
Since then, the EPA has been assessing and working with the state and others to try to contain the towering waste piles, open pit lake and old leach ponds spread across an area the size of 3,000 football fields.
Last January, more than 100 residents filed a $5 million class-action suit in federal court in Reno accusing Atlantic Richfield Co. - which bought Anaconda Copper Co. and closed the mine in 1978 - and its parent BP PLC of intentionally and negligently concealing the extent of the contamination for decades.
A hearing is scheduled Feb. 13 on Atlantic Richfield's motion to dismiss the suit.
EPA sampling of a different type in 2010 found that 79 percent of the domestic wells tested within two miles north of the mine, where the tribe's land begins, had dangerous levels of uranium or arsenic or both and that the water was unsafe to drink. Uranium was detected at more than 10 times the legal drinking water standard of 30 micrograms per liter in one monitoring well a half mile north of the mine, and at more than 100 times the standard at the mine itself.
Since 2004, BP has been providing bottled water to hundreds of residents whose wells showed concentrations of uranium greater than 25 micrograms per liter. But tribal leaders said irrigation wells for crops have continued to be pumped with very little known about the potential impact from the uranium and other contaminants.
The EPA's Johnson said the agency is continuing to investigate the extent of groundwater contamination. She did not directly respond to questions about whether the EPA considered the onion survey sample size to be scientifically sound, but acknowledged the study was "limited in scope."
It was "intended as a limited, opportunistic survey to look at potential impacts to a crop that was grown in close proximity to the site, irrigated with water that was representative of site groundwater contamination, and potentially impacted by airborne transport of contaminated dust," she said in an email to the AP.
"The results did not indicate that the mine had affected the onions," she said. "We have no information at this time that any other irrigation wells are drawing from groundwater impacted by the Anaconda site."
But Dietrick McGinnis, environmental consultant to the tribe, said the EPA hasn't identified the dimensions of the toxic plume or how far it has traveled.
"They have no idea what the extent of the contamination is," he said.
Scientists caution that appropriate sample sizes can vary.
"But obviously this is not a representative sample, and CH2M Hill said so," said Susan Kegley, principal and CEO of the Pesticide Research Institute in Berkeley, Calif., of the onion sample.
Kegley said she might sample onions from each of five different locations spread over an acre. She'd probably compare onions irrigated with river water versus groundwater and sample onions that had been peeled and processed versus those with soil still attached to help determine if uranium was in the soil.
"I'd also hesitate to use the word 'safe' and uranium in the same sentence,'" she said. "There is no safe level of uranium. There are acceptable levels that have been established for various standards."