Green water isn't the only controversy swirling around swimming events in Rio. US researchers say a possible design flaw in the pool produced a water current that gave some swimmers an unfair advantage, reports the Wall Street Journal. Specifically, they say that swimmers in the high-numbered lanes of 4 through 8 got a boost over those in lanes 1 through 3 in the men's and women's 50-meter races. Five of the six medalists came from the higher lanes, the lone exception being US gold medalist Anthony Ervin from lane 3. What's more, 15 of the 16 swimmers who qualified for the finals did so from the higher lanes. The world swimming body FINA is investigating, given that a similar problem uncovered by the same researchers affected the 2013 world championships.
"Disappointing" but not surprising, researcher Joel Stager of Indiana University tells the Guardian. As is sometimes the case in world competitions, the pool at Rio is a temporary one that will be taken down afterward. Maker Myrtha Pools says tests conducted before and during the competition—which involved floating a large jug—found no evidence of a current. Assuming the anomaly existed, it would have affected longer races, too, but in a more complicated way—the same current that boosted swimmers in the one-lap 50-meter race would have worked against them in the opposite direction. (Read more Rio Olympics stories.)