It is no secret that Brazilian officials will fall seriously short in their promise to clean the polluted ocean waters where swimmers and sailors will compete at the 2016 Summer Olympics.
Now, an internal memo obtained by ESPN.com shows that U.S. Olympic Committee officials became convinced last fall that American athletes will risk illness by taking part in events on Guanabara Bay.
The October document was prompted by a meeting with the International Olympic Committee's medical commission and other experts in Lausanne, Switzerland.
"The IOC and Rio Organizing Committee recognize that the water quality in and around Rio is for the most part not at an acceptable level and there [are] significant fluctuations in the bacterial and viral contaminants at the competition venues," the memo said.
"The levels of pathogens will fluctuate depending upon environmental impacts and especially with significant rains," it continued. "The IOC is tracking the weather impact using historical data. Additionally the IOC and Rio organizers are studying the current flows in and around the competition venues."