I think it would be a good idea to also have a secondary entrance to the sewer(s) below the water wheel(s) in town(s). Distorted view for the first few steps from falling water falling from above could add to the Cool factor IMHO.
Well you know, the best place for an entrance to sewers is that of a high point, far away from water, just outside any other area of interest. You know because they are really secret... *sigh* Sorry pet peeve of mine.