DENVER (AP) -- A worker at a federal laboratory in Colorado intentionally manipulated test results for years, possibly tainting research that includes toxic metals in the Everglades, uranium near the Grand Canyon and coal in Afghanistan, investigators say.
The falsified data from a U.S. Geological Survey lab may have affected 24 coal, water and environmental research projects costing a total of $108 million, according to a report released recently by the Interior Department's inspector general.
USGS spokeswoman Anne-Berry Wade said Thursday the agency isn't sure why the employee falsified the results of chemical analyses but said it wasn't for personal gain or "any nefarious reason."
A notice on a USGS website said the manipulation was done in part to correct calibration failures in the instrument being used, a mass spectrometer.
Wade said USGS had taken action against the employee but declined to say what it was, citing privacy rules. She also declined to say whether the employee was still working for USGS or to release his name.
Wade said any request for a criminal investigation would be made by the inspector general's office. Officials in Washington and Denver didn't immediately return after-hours phone calls Thursday.
The manipulation occurred between 2008 and 2014 at the USGS Energy Geochemistry Laboratory in the Denver suburb of Lakewood, the inspector general said. The test samples were mostly coal and water.
The researchers whose test data may have been manipulated were notified, according to the report dated June 15. Wade said one USGS report that used the falsified data was retracted, revised and republished. A second USGS report was revised before it was published.
The laboratory is part of the USGS Energy Resources Program, which studies potential energy sources around the world. The program made headlines two weeks ago when it said western Colorado contained 40 times more natural gas than previously thought, making it the second-largest gas formation in the country. There was no indication that report relied on the falsified data.
Researchers around the world rely on USGS data, and it often shapes laws, regulations and policy. The inspector general's report said the bad data from the Colorado lab could erode confidence in the entire USGS.
Wade said the USGS doesn't believe the tainted data affected any decisions by lawmakers or regulators.
"We can only hope that this incident won't have a long-lasting effect on the agency's reputation," she said.
USGS managers halted all work at the laboratory when they discovered the manipulation in late 2014, Wade said. In February 2016 the agency permanently closed the section of the lab that was involved.
The inspector general's report raised questions about why the problem went undetected for so long, saying employees were suspicious of the lab's work for years. Wade said a new lab director took over in 2014 and decided to look into the suspicions.
Investigators previously found that mass spectrometer operators in the same lab violated standards between 1996 and 2008. Investigators said the operators were making excessive adjustments in instrument readings to compensate for calibration problems.