It is worth remembering that this water is not all that it seems to be. Not only do fish and birds crap in this water, so do humans in a round about way. Sewerage treatment works pump waste water into the river and stormwater finds it way there eventually with its load of dog pooh, oil and all manner of rubbish. Swimming in it is not recommended in many places and eating shellfish from it is only for the foolhardy.
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