I finally got curious about the signs they put out for us and all of the talk about the polluted river and spent days researching the issue.
Here’s the short version: The “precautionary” warnings (like catfish in the Nickajack section) have very little evidence behind them. The “do not eat” warnings (like you have for several species on Watts Bar) are linked to older studies (at least a decade, but I don’t remember offhand) where the fish showed elevated levels of things like mercury and PCBs.
At one point, someone decided to research the effects of heavy fish eating of the “polluted” fish in Watts Bar. Turns out that heavy eaters of “polluted” fish showed exactly the same levels of PCBs and mercury as the general population, which are well under any worrisome level.
So, there’s little evidence that the precautionary warnings represent actual levels pollutants which would be harmful to humans. When the levels do cross the line assumed to be dangerous, there’s no evidence that they actually are dangerous. While the zero-tolerance to pollutants model seems to be reasonable, in actuality it is not. We are all exposed to pollutants in our daily lives and seem to do fine. Car exhaust is probably far, far worse for us than any level of “polluted” fish we could possibly consume.
