JDP - You wrote "If you can't rely on the govt bio guys, who do you look to?" Often you shoud get a second opinion. Professional advisors are not all knowing. As you discovered, second opinions can be informative and result in two differnt answers. Sometimes there is no definite or exact answer. Some topics are very complicated and you have to do what you think is best in your situation.

Dave, a water sample may not reveal presence of trihalomethanes since they are not water soluable, but fat soluable and deposited in tissue. I think if you want to check for their accumulated concentrations, the fish tissue (predators)should be analyzed; similar as tests for PCB's, mercury, etc. The analysis lab would be able to better advise you on this topic. This is a fairly new science and I don't even think the EPA has even established limits for accumulations in animals. Many manmade chemicals are present in the environment and I don't think we as a society know very much about their long term affects and the affects of their chemical recombinations have on our health. It is an ongoing science.


Since you and Canepole only used chlorine once in the pond, the concentrations of chlorine residuals may not be at toxic or harmful levels. The danger comes when chlorination processes are routine procedures. Many manmade chemicals are not toxic at very low concentrations, but if they can accumulate and be stored in tissues then long term exposure can become a problem.

aka Pond Doctor & Dr. Perca Read Pond Boss Magazine -
America's Journal of Pond Management