The Rogue and about a dozen other Oregon rivers are poised to join the state's growing list of mercury-impaired waters tapped for future cleanups and other efforts to reduce levels of this toxic pollutant.
The state Department of Environmental Quality has proposed adding the entire 216 miles of the Rogue River — including the main stem upstream of Lost Creek Lake — as well as Emigrant Creek on the list of water bodies with high levels of mercury in resident fish.
The findings also are expected to lead to future public-health advisories limiting the amounts of resident fish people eat from Rogue Basin waters. But those won't include the Rogue's famed salmon and steelhead, which don't accumulate mercury in their bodies like other fish do, toxicologists say.
Tests on nonnative pikeminnow collected from the Rogue in 2010 near what used to be Gold Ray Dam and Robertson Bridge in Josephine County showed levels more than 10 times above the state's water-quality standards for toxic pollutants.
If adopted later this year, the designation would lead DEQ scientists to determine what levels of mercury in the Rogue are safe and develop a plan to get them there — and address any natural or artificial sources of mercury.
It's the first time the DEQ has looked for mercury in the Rogue.
The DEQ is proposing similar designations for the Clackamas, McKenzie and North Santiam as well as the mid-Columbia River. Other streams, such as the Willamette River, were studied for mercury last decade.
"As we look more closely for mercury, we're finding it at these elevated levels," said Bill Meyers, the DEQ's Rogue Basin coordinator. "That indicates to me it's a broader problem than the Rogue."
The DEQ chose to sample pikeminnow, which generally are not consumed by humans, because they are resident fish that help provide a snapshot of the basin's water quality, Meyers said.
The DEQ tests did not sample the Rogue's salmon and steelhead, whose adult biomass is made up primarily of food consumed in the sea.
"Wherever we look, the pikeminnow seem to have the highest mercury levels," said David Farrar, a public-health toxicologist for Oregon Public Health. "Salmon and steelhead have some of the lowest levels of mercury we find. They're just passing through."
Oregon Public Health expects this spring to issue advisories against eating too many pikeminnow in the Rogue as well as warmwater fish in Applegate Reservoir, Farrer said. Those advisories will be issued once toxicologists calculate how many meals per month are considered safe, he said.
Forrest English, of the Rogue Riverkeeper program, which is the water-quality arm of KS Wild in Ashland, said the levels of mercury clearly will have people questioning their fish consumption. He wants to see the mercury surveys expanded to include tributaries.
"This is a big red flag that there's a lot of mercury in the system," English said. "Whether it's naturally occurring or not, there's still a human-health risk we have to take pretty seriously."
High mercury levels have been documented for decades in smallmouth bass and other nonnative, warmwater fish in Emigrant Lake, most recently in 2006. A standing public-health advisory has been in place there against regular eating of all Emigrant-caught fish except trout, particularly among pregnant women.
In 2006, tests on Emigrant Lake trout showed levels of mercury far above safe levels.
It comes as little surprise to see mercury in the Rogue's pikeminnow, which are long-living fish-eaters that are not native to the basin, said Russ Stauff, the Oregon Department of Fish and Wildlife's Rogue Watershed manager.
His agency plans to coordinate with DEQ officials to learn more about the issue and keep anglers and others who eat Rogue fish apprised, Stauff said.
"This is a big deal to understand," Stauff said.
The DEQ is taking public comment on its Draft 2012 Integrated Report Assessment Database and its list of proposed water-quality limited streams through Feb. 3.
Done every two years, the draft contains information on the quality of Oregon's surface water and lists pollutants found to exceed minimum levels.
Listing in the assessment starts in motion a series of more studies, the determination of total amount of the pollutants allowed in the stream to remain healthy and a plan to make that happen, similarly to how DEQ deals with improving dissolved oxygen and other water-quality issues.
While mercury in Emigrant Lake bass was traced to natural deposits, part of the plan for the Rogue will be tracing those sources as well, Meyers said.
"We don't know whether it's erosion of native soils, legacy mines, other mining or what," Meyers said.
Mercury is a toxin most dangerous to fetuses because it can cross the placenta. It is known to cause permanent problems with developing brains.
Mercury is a worldwide health issue and so prevalent in the aquatic food chain that it's present in virtually all fish, including those caught in the ocean.
Because the element builds up over time in a fish's flesh, older and larger fish tend to have higher concentrations of mercury. Since mercury chemically bonds with muscle tissue, it cannot be removed or significantly reduced by fish-cleaning methods, cooking, brining or smoking.
Reach Mail Tribune reporter Mark Freeman at 541-776-4470, or email at email@example.com.