The trout in Silver Creek now have a reason to be nervous.

A fish consumption advisory that had warned of elevated mercury levels in Silver Creek’s trout is no longer in place. That’s because state officials have discovered an error in the 2007 lab test that spawned the advisory.

With the advisory lifted, it’s now safe to eat fish from Silver Creek near Picabo, provided they were caught in areas where state regulations allow anglers to harvest rainbow and brown trout, the Idaho Department of Health and Welfare said Tuesday. Previously, the state had recommended that children 15 and younger and women who are pregnant or nursing eat limited quantities of brown trout because the mercury levels were believed to be dangerous.

In 2007, the United States Geological Survey had taken samples of fish from Silver Creek, which lab test results showed high mercury levels and prompted the advisory. USGS staff reviewing more recent test results saw a major drop in the mercury level of fish compared to two years ago, which raised eyebrows because mercury levels in fish don’t drastically change in that time frame, officials said.

After its lab reviewed the 2007 test results, USGS realized that there was a calculation error in how the mercury levels were figured out. USGS, which shares its data with the state, passed that information on to the Idaho Department of Health and Welfare.

“We think it’s pretty unfortunate there was a miscalculation to begin with,” said Jim Vannoy, environmental health program manger for Health and Welfare. “We don’t want to scare people away from eating fish,” he said.

To be on the safe side, state officials took additional samples of fish last week from Silver Creek and tested them for mercury. The results showed levels of mercury that do not require an advisory. The levels were also similar to the recalculated levels of mercury in fish samples from 2007.

Vannoy said a check of the research done at other fishing sites with mercury advisories in the state showed that Silver Creek was the only location in Idaho that was based on incorrect information.

“We think it’s unfortunate that it happened in the first place but it was an error that erred on the side of safety,” he said.

USGS had no data prior to 2007 to compare the first lab test result to, which resulted in the error not being noticed sooner, said Terry Maret, a biologist with USGS.

Ben Botkin may be reached at bbotkin@magicvalley.com or 207-735-3238.