German swimming coach Bernd Berkhahn has expressed concern over the uncertainty over where the Olympic open water swimming events will take place in three weeks in Paris. The open/marathon swimming is supposed to be held in the river Seine along with the swimming portion of the triathlon. However, due to high levels of bacteria in the Seine at present, the Olympic rowing canal may be used instead. Germany’s Florian Wellbrock, the 10-kilometre open water champion from Tokyo, will again start as favourite but the build-up is far from ideal. “It is a bit frustrating for the athletes and the staff…