Two Oxfordshire triathletes competed in races last weekend despite the previous wet weather.
Nigel Chaney, who is part of Bicester Triathlon Club, was at the 'very hilly' Hever Castle near Kent to race the super sprint triathlon.
However, due to 'unsafe' lake water, it was amended to a duathlon, which consisted of a 5k run, 20k bike, and a 2.5k run.
A statement on the website said: "This decision has been made in the best interest of participant health and safety following the wettest September on record in Hever.
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"The heavy rainfall over the past week has led to high levels of overspill and run-off being discharged into Hever Lake.
"Multiple water quality tests have been conducted, and the most recent results indicate the lake is unsafe to swim in."
John Orridge, also from Bicester Triathlon Club, raced at the Kingston Wheelers 10 mile TT road cycle in Surrey on Saturday, September 28.
Mr Orridge finished with a time of 24.43 minutes.
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Bicester Triathlon Club welcomes athletes of all skill levels, with training groups designed to cater to various age groups.
Established in 2012, the 'friendly' club prides itself on providing 'fantastic' coaching for triathletes of varying abilities from beginners to competitive athletes.
The club welcomes children from seven years old all the way through to adults.
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