The major leadup event to the New Zealand Ironman in Taupō in March has been forced to change because of issues with the water quality in the lake.
Tomorrow's Ironman 70.3 - or half ironman - will not have a swim element.
Due to dense mats of potentially toxic algal species at five sites around Lake Taupō, prompting a Council warning for the public to avoid swimming in affected areas, organisers have been forced to remove the swim leg and implement a contingency course, consisting of a 3km Run, 90km Bike and 21km Run.
After receiving reports from the public of algae blooms, Waikato Regional Council scientists collected a number of algae samples on Tuesday and again on Wednesday from five sites.
Testing overnight by NIWA scientists has confirmed the presence of potentially toxic algal species, including Phormidium, at areas within Five Mile Bay, Acacia Bay, the main lake front in Taupō, Whakaipo Bay and Kinloch Beach.
Race organisers were notified of the warning at 8pm last night, and are notifying all registered athletes of the change, and the options open to them.
Race director Wayne Reardon acknowledged this was not the race athletes were hoping for, but said the health of all competitors was the first priority in this situation.
"We know athletes will be disappointed about this news, as we are. However, our team are still committed to putting on a fantastic race on Saturday, albeit in a modified format. We look forward to seeing athletes at Athlete Check in tomorrow and on the start line on Saturday."