PARIS — The cleanliness of the Seine river is casting a shadow over a successful Paris Olympics. Data from water utility Eau de Paris obtained by POLITICO on Friday showed that the water quality was not safe to swim on most days during the Olympics and was of questionable quality on Monday, the day of the mixed relay triathlon. The data did not indicate that it was unsafe to swim on the days the men and women triathlon races were held. While the high levels of bacteria led to several practices being canceled and the men’s triathlon being postponed once,…