Recently I was engaged in an on line conversation about fishing in Lake Lewisville
, a lake that has discharge effluent from a sewage plant. It reminds me that it is important to consider the places we fish.
Here's what I said: I've built and modified well over a dozen waste water treatment plants.
Most of the time they discharge clean water. It will have been filtered of solids (like condoms and tampons), aerobically or anaerobically "composted" while in liquid form, run through a settling basin to get the "sludge" out of it, then chemically treated, usually with chlorine and ammonia, to kill the micro organisms still residing in the water. It will not have been treated to remove residual drugs (like birth control hormones or anti-depressants) or heavy metals, or random chemicals.
Most of the time the discharge is clean of biological presences.
All sewage plants are at the downhill end of the city they serve, sewage arrives via the power of gravity. During heavy rains they can and often do overflow - and when they overflow they pour raw untreated sewage out the discharge pipe. This is a periodic event, that's true, but it is not pleasant to be downstream of a sewage plant when it overflows.
I personally, knowing what I know and having seen what I have seen, would never choose to live downstream from a sewage plant, not ever. Not if I had any other choice. I would not eat fish from a lake that has sewage plant discharge - there's probably an extremely small chance of those fish making you ill - but I would not do it myself.
As I said, the probability of getting sick from eating a fish that lives in a lake that has sewage discharge is small. But...when you know that contaminants can be present that you do not want in your stomach, you get to make a decision. You get to make that decision. My decision is to go somewhere else.
Here is a real life example of my decision. A friend of mine has a deer lease in a beautiful part of Texas, down near Menard. It is on the San Saba River. I used to go there in the off-season with him and fly fish the Lampasas. It's beautiful and the fishing is great. Then one day while we were driving around I noticed that the Menard wastewater is released up stream of the lease. I've never been back. Not only would I not eat the fish (which would be rare for me anyway), I do not want to wade in the water no matter how clear and beautiful it is. MY choice. It was a great fishing spot and while I hated to give it up, there are other great spots that don't have sewage plants a few miles upstream.
By the way, I used to play a lot of golf and would always decline to play on a course irrigated with sewage effluent - just in case the sprinklers came on while I was on the course.
Your mileage may vary.