Canoeists criticised the water quality at Rio de Janeiro's Olympic rowing venue after the second day of competition in the sport's official Rio 2016 test event.
Athletes on Saturday complained about a breakout of algae and weeds at the Rodrigo de Freitas lake, which will also host Olympic rowing events next year, Xinhua reported.
"The level of competition is high and unfortunately the algae is affecting the performance of some athletes," Portuguese canoeist Fernando Pimenta told newspaper Folha de S.Paulo.
Brazilian Paralympic athlete Debora Benevides was more scathing, saying the venue was unfit to host Olympic events.
"The water isn't good and the venue is not appropriate," Benevides said, adding: "There is a lot of weed sticking to our paddles. Imagine this happening in an Olympic competition."
Austrian Olympian Viktoria Schwarz posted a photo on Instagram showing some of the algae she encountered during her K2 500m sprint event alongside teammate Ana Roxana Lehaci.
"Finished the season with a 4th place in the Olympic Test event in Rio," Schwarz wrote. "The course is beautiful but the water is full of weed. So it felt more like a 500m with resistance."
Rio 2016 canoeing manager Sebastian Cuattrin said the high level of algae was due to abnormally warm weather.
"We are looking at the problem and mapping it. It's going to be perfect for the games," he said.
