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Mercury in Our Air, Water, Soil and Fish



In April of this year the Oregon Health Authority (OHA) issued a warning about consuming too many bass found to be contaminated with excessive amounts of mercury in fish tissue sampled from a number of water bodies across the state.

Dave Farrer, Ph.D., toxicologist in the Environmental Public Health Section at the OHA Public Health Division, said, "Fish are an important part of a healthy diet, especially migratory fish like salmon, steelhead and trout. The elevated mercury levels we're talking about in bass are of concern to us, but there are some simple steps people can take to reduce their exposure to mercury when consuming bass."

Like it or not, bass are alien trash fish in Oregon. According to research conducted by Rick Moberly, Fish Biologist with Oregon Department of Fish and Wildlife, largemouth bass were introduced illegally into Crane Prairie in the late 1970s or early 1980s. ODFW had nothing to do with their sudden appearance, and first found them while electrofishing in May 1986.

It's the same with Davis Lake: their presence wasn't confirmed by ODFW until 1995. It's assumed all the other state-wide bass introductions are also the results of anglers who just wanted to fish for bass in Oregon, without any regard for the impact of their selfish desires on native fisheries and the aquatic ecosystem.

Bass are considered a top predator, eating other mercury-contaminated fish within an ecosystem; therefore, the longer bass live, the more mercury they accumulate. They are found across the state in many popular fishing waters. Unfortunately, the state does not have enough data to warrant a statewide advisory.

OHA, however, recommends the following monthly meal allowances for bass from all water bodies across the state, including river systems:

-General population—Limit consumption to no more than six meals per month.

-At-risk populations (pregnant women and children)—limit consumption to no more than two meals per month.

-A meal is about the size and thickness of your hand; for children, a meal is about the size and thickness of a child's hand.

For a list of water bodies with an existing advisory, see the advisory table at People should follow the recommended meal allowances for fish from these individual water bodies, rather than the statewide meal allowance of six and two.

Where does the mercury come from? Contrary to popular belief, it is not a foreign element to the ecosystems of Earth; it occurs naturally in deposits throughout the world, mostly as cinnabar. During WWII cinnabar mines were as common as pot smokers in Bend. Mining claims could be found all up and down the Bear Creek Country, out on the Great Sandy Desert, and in other locations throughout Oregon.

That's because mercury was a much sought-after element in the manufacture of triggers for bombs dropped by Allied bombers on targets in Italy, Germany, Japan and other enemy installations. It was also used in the manufacture of electrical switches, and no one knows precisely how much cinnabar/mercury from the old tailings went down the nearby creeks and into nearby water storage facilities and fishing holes.

Mercury was once used exclusively in thermometers, barometers, float switches, relays and fluorescent lamps, but concerns over the element's toxicity changed things dramatically.

And now we get to the nitty-gritty of this discussion: serious mercury-poisoning can result from exposure to water-soluble forms of mercury (such as mercuric chloride or methyl mercury), by breathing it in as a vapor or by ingesting any form of it—which brings us to mercury in fish.

Back in 1994 the Oregon Health Division advised anglers to limit the intake (eating) of fish from several bodies of water within the state. Antelope, Owyhee, and Brownlee Reservoirs, stretches of the Columbia, Snake and Willamette Rivers, and East Lake were among the bodies of water containing fish that tested high in mercury levels.

East Lake's fish tested positive, while Paulina Lake's fish did not. The source of mercury in East Lake fish is natural, likely due to the volcanic nature of Newberry Crater, which is still active in this particular body of water. As most of us "old-timers" know, there are residual hot springs along the shores of East Lake, especially at the site of the once famous East Lake Spa of the early 1900s. It is indeed possible that those hot springs are the main source of mercury in East Lake.

The status of mercury in East Lake today is anyone's guess, because the water has not been tested in many years. However, OHS officials believe that, because the source of mercury probably comes from the volcanic vents in the lake, the mercury level hasn't changed all that much since the 1994 report. That said, you're on your own if you consume fish from that body of water.

Methyl mercury increases in concentration as it moves up the food chain, and because it accumulates in fish, eating fish is the way most people are exposed to mercury in the environment. It can also cause a range of toxic effects to fish, aquatic life and wildlife.

Mercury primarily affects a warm-blooded animal's nervous system and is particularly dangerous for infants and young children, whose nervous systems will continue to develop through adolescence. For developing fetuses, it can be even worse. Mercury can be passed from mother to fetus, resulting in potentially serious effects, such as brain damage, mental handicaps, blindness, seizures, and speech problems. Babies born to mothers who have elevated mercury levels may have developmental issues and learning disabilities.

What's being done to clean up this mess? That's a hard one to answer because the mercury is not only coming from natural sources, but is also getting into our air and water because of human activity.

In fact, humans release thousands of tons of toxic mercury into the environment every year from coal-fired power plants, cement kilns, chlor-alkali plants, trash incinerators, and gold mining. Much of it collects in sediment, where it is converted into toxic methyl mercury and enters the food chain, ending up in the "sport fish" we eat.

In the meantime, things don't look so good for anglers looking to land a lunker Kokanee, or Atlantic salmon for dinner. The bigger the fish, the better the chance it has too much methyl mercury for a human to handle. Health advisories from various health agencies suggest keeping little legal fish and putting big ones back.

To muddy the waters further, ODFW recently recommended limiting consumption of all fish but rainbow trout from Emigrant Lake, 20 miles southeast of Medford, due to mercury levels.

Yes, the Oregon Department of Environmental Quality is on top of the mercury problem with both hands and both feet. They are identifying waters where fish tissue samples have higher-than-standard mercury levels and adding them to the state's list of impaired waters. DEQ then collects additional information and conducts analyses to determine the severity and extent of the problem, identifies the sources of mercury, and develops restoration plans to reduce the levels of mercury reaching Oregon's water ways. But tax dollars can only go so far.

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