how would you expect,turbidity,BOD values and numbers of E.coli to compare in a clean water area and an are ju

Question

just below a sewage outfall

Answer 1

Without real data, it is impossible to answer your question. The two extremes of the situation would be 1) downstream would equal the outfall or 2) the outfall will make no difference.

You need to know the flow of the stream and the outfall and the data on the outfall. I have worked with industrial outfalls where the stream was healthier after adding the outfall. I have also worked with bad outfalls, that when a treatment breakdown occurred, fish were killed.

The bottom line in the USA is for the volumes and components of the outfall not to have a serious impact on the stream. If all things are conducted correctly, downstream values should not be more or less than 5% of the upstream values, except in rare cases and in most of those, the stream quality will improve.

Answer 2

IN THEORY, the clean water would have less turbidity (the water would be clearer), lower BOD (biological oxygen demand - no sewage decomposing or bacterial respiration to need O2), and lower E. coli (intestinal bacteria) than directly below a sewage outfall..