Event organisers Nova International decided to cancel this weekend’s outdoor swim due to a potentially dangerous level of blue green algae detected in the water, which could put swimmers at risk of infection.
The organiser’s contingency venue was also ruled out due to concerns over the levels of algae.
Swimmers taking part in the event, which is part of the nationwide Great Swim series, could choose between three distances: ½ mile, 1 mile and 2 miles.
The loch has been closed for immersion sports for two months following an outbreak of illness contracted by open water swimmers who took part in an event in June.
As a result, North Lanarkshire Council, in consultation with the Scottish Environment Protection Agency and other environmental bodies, commissioned a water quality risk management protocol report.
Alex Jackson, event director of the Great Swim Series said cancelling the Great Scottish Swim has been an "extremely difficult" decision. "The safety of our swimmers and their families remains our main priority. The strict guidelines that are in place mean, for us, there is an unacceptable level of risk.
"We had hoped to find an alternative venue, and extensive research was done to this end. An event of this size requires considerable infrastructure which immediately discounted some very good options. We had identified a promising location with full operational plans in place, but unfortunately, as of Sunday, water quality here has deteriorated also, and it is no longer suitable."
Organisers say all swimmers will be offered a full refund on their entry fee.
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