Michael Phelps' coach admits "grave concerns" over pollution risks for athletes at Rio 2016

Bob Bowman, coach to swimming legend Michael Phelps, has added his voice to concerns over water pollution levels in Copacabana Bay ©Getty Images

Michael Phelps' coach Bob Bowman has claimed he has "great concerns" surrounding water pollution at next year's Olympic Games open water swimming venue on Copacabana Bay here.

Bowman's concerns stem from working with two athletes, who, he believes, suffered long-term damage after competing in the same waters at the 2007 Pan American Games.

Kalyn Keller, who Bowman used to coach, finished fourth in the women's 10 kilometres race eight years ago and was later diagnosed with Crohn's Disease, an inflammatory bowel disease, forcing her early retirement from the sport.

Chip Peterson, winner of an 10km open water silver medal, as well as 1500m freestyle gold in the pool at those Games, also developed ulcerative colitis soon after, a similar disease which gave him episodes of abdominal pain, fever diarrhea and blood loss.

He has since undergone three surgeries but is still competing.

"In terms of the water quality of the open-water swimming, yes, I have great concerns about it," Bowman, who has coached Phelps to a record 22 Olympic medals, including 18 gold, told the Agence France-Presse.

"I happened to coach a young lady at the 2007 Pan Am Games there, and she came back and has been sick the rest of her life with a life-altering illness

"So I know first-hand that it's serious.

"They've got to do something about it."

Chip Peterson was among athletes to develop illnesses after competing in Copacabana Bay during the 2007 Pan American Games ©Getty Images — American Chip Peterson was among athletes to develop illnesses after competing in Copacabana Bay during the 2007 Pan American Games in Rio de Janeiro ©Getty Images

Concerns have been raised over high-levels of pollution at venues for all water sports to be held at the Olympics and Paralympics, consisting of Copacabana Bay, the Lagoa Rodrigo de Freitas where rowing and canoe sprint will be held, and the Guanabara Bay sailing venue, where the gravest fears have been expressed.

These have been exacerbated in recent weeks following the publishing of the results of a six-month Associated Press investigation which found "major risks" of athletes contracting viruses when competing at all of these venues, including the specific area where open water swimmers will enter the water.

A flotilla of almost 30 boats ambarked on a protest voyage this weekend by the Marina da Gloria where sailing is due to take place south to Sugarloaf Mountain.

Honking foghorns, blowing rescue whistles and chanting, the group, united by the slogan "baia viva!", meaning "the Bay lives!"

The group are aiming to carry out many similar protests over coming weeks to bring further attention to the problems.

Brazilian officials have fought hard to play down these concerns, with International Olympic Committee President Thomas Bach paddling in the waters of Barra de Tijuca after insisting the venues will be safe for athletes competing when visiting as part of one-year-to-go celebrations earlier this week.

International Swimming Federation President Julio Maglione has also claimed the cleanliness of the water is "not a big problem at the moment".

He did, however, promised to maintain contact with the International Triathlon Union, who have conducted independent testing of the waters, the same ones to be used by open water swimmers, following the completion of a test event here last week.

Protesting on Guanabara Bay campaigning against — Protesters gathered on Guanabara Bay to campaign against "broken promises" regarding cleaning the water ©AFP/Getty Images

Rio's State Government also found high levels of pollution when monitoring Copacabana Bay last week, with an area close to the Olympic course reportedly declared "unfit for swimming".

They claimed that this was because of dirty water on the street draining onto the beach following rain, with subsequent tests showing safe levels.

Almost all triathletes competing at the test event, including Britain's reigning Olympic champion Alistair Brownlee, said they were unconcerned about swimming in the waters, although some did admit that the waters were "filthy".

Meanwhile, following much criticism that a pledge to use the Games to reduce wider polluton levels across the city has gone unfulfilled, a partnership has been announced between the State Government and seven universities, as well as several research institutes, to develop a new clean-up plan.