Silver Creek is pristine after all — mercury scare was based on faulty data

A two-year-old warning against eating too many brown trout from Silver Creek near Picabo has been lifted after scientists realized it was based on faulty data.

United States Geological Survey staff noticed the error when they started looking at newer data that showed a dramatic drop in mercury in fish. Reviewing the 2007 report, USGS staff realized the lab had miscalculated last time.

Q: So what does this mean?

A: Few anglers keep Silver Creek fish - much of the stream is managed by the Nature Conservancy for catch-and-release-only fly fishing. So practically speaking, the change won't mean much. But it does mean that the river has not had the mercury contamination other state waters have shown.

Q: How many other waters have fish advisories?

A: In Idaho, about 20 have specific advisories, but in all state water, anglers are warned not to eat more than one meal of bass caught each week - and pregnant women, women who plan to become pregnant, nursing mothers and children under 15 should not eat more than two meals of bass a month.

Q: Does that mean we shouldn't eat fish at all?

A: No. The EPA recommends that people eat up to two meals a week of seafood low in mercury, including fish caught from waters without advisories and shrimp, canned light tuna, salmon and pollock.

Q: How do we know that other advisories are accurate?

A: All of the labs used to test fish have strict quality assurance programs and quality controls, said Jim Vannoy, the environmental health program manager who oversees the Idaho Fish Advisory Program. The state itself and the other labs it works with use a different method to test for mercury in fish and don't use the kind of calculations used for the Silver Creek samples. The mistake made was tied to these specific results, Vannoy said.

After the mistake came to his attention, Vannoy said he went through the state's other results to make sure they were valid.

Q: How much testing is the state planning?

A: Because of budget cuts, no more water monitoring or fish testing is planned.

Q: Where does the mercury come from?

A: All over the world and from local sources, such as gold mines in Nevada and a concrete plant in Oregon.

Q: What is Idaho doing about it?

A: The Idaho Department of Environmental Quality and environmental groups such as the Idaho Conservation League have pushed Nevada and Oregon to regulate mercury there. DEQ also is writing rules that require major mercury polluters to use the best available controls to remove mercury from their emissions. The only existing plant that would be affected, Monsanto's Soda Springs facility, is involved in the negotiated rulemaking, along with other companies that would not be regulated but oppose the rules.

Q: What about the federal government?

A: It also is preparing to write rules to regulate mercury.

Rocky Barker: 377-6484