At the south end of the Eastbank Esplanade, people lie in the sun and swim in the river, endorsed by WW. At the north end of the Esplanade, a sign says not to eat fish caught in the river. Who should I believe?

—David J.

Don't take this the wrong way, David, but you seem to be having some difficulty with the distinction between "things that are safe to eat" and "things that are safe to touch."

Don't feel bad, plenty of people share your confusion. (Most of them are toddlers, but whatever.) Still, the fact that the Willamette River's resident fish can be contaminated doesn't have much at all to do with how safe it is for you to gambol, porpoiselike, in its waters.

The reason we used to avoid contact with the river was that it was frequently rife with raw sewage due to Portland's antiquated sewer system. Since the completion of the $1.4 billion Big Pipe project, that problem is mostly behind us.

The fish, though, are an unrelated issue: We're advised not to eat them because their flesh accrues pollutants like mercury and PCBs, left over from the days when we thought it was hilarious to dump industrial waste into the river.

I realize this sounds like I'm telling you to stop swimming in a river filled with human excrement and start swimming in a river filled with toxic waste. In fact, though, the water itself is safe; it's the sediments on the bottom that are contaminated.

The fish that live down there can accumulate dangerous levels of these toxins, but only after a lifetime of eating them. Your 20 minutes of swimming in the adjacent waters is no big deal.

It's not ecologically ideal, and we probably won't be getting a medal from Elrond of Rivendell for outstanding environmental stewardship anytime soon. But it beats swimming in shit.

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