Swim Serpentine 2023: Event going ahead after blue-green algae decreases

A major swimming event in Hyde Park this weekend will go ahead following concerns it could be cancelled due to the discovery of blue-green algae.

Swim Serpentine is due to take place on Saturday (September 16), featuring six-mile, half-mile, one-mile and two-mile swims.

Organisers posted on X on Wednesday that they were considering whether the event would go ahead, but on Thursday confirmed blue-green algae had decreased.

They wrote: “We are delighted to confirm that we are going ahead with Swim Serpentine on Saturday. As we explained in an email to participants earlier today, we have been working hard to reduce the level of blue-green algae to enable Swim Serpentine to take place on Saturday and have been conducting daily testing of the water.

“We’ve just received the results from the water samples we took this morning (Thursday September 14). Standard testing results measure water quality as excellent and our specialised testing shows blue-green algae levels are continuing to decrease.”

They wrote that levels “are deemed safe for swimming by our expert water safety team”, adding: “We’ll continue to monitor blue-green algae levels in the Serpentine with further tests tomorrow and will notify you immediately if there is any change to the event going ahead.

“We will also be providing additional measures on the day including extra showers and drinking water for participants. If you’re still able to join us on Saturday, you don’t need to do anything, and we can’t wait to see you!

“However, any participants who are still not comfortable with swimming have been emailed directly with their options.”

Blue-green algae

On Tuesday organisers had posted: “As you may be aware, there has been a bloom of blue-green algae in The Serpentine (which is a common occurrence during hot weather).

“Swim Serpentine is scheduled to take place on Saturday September 16, and we have been taking weekly and now daily water samples from the water.

“Staff have been doing everything possible to clear the lake and positively water samples are showing a decrease in blue-green algae levels.

“Further samples have been taken from multiple areas of The Serpentine today, to enable us to make an informed decision by 5pm tomorrow (Wednesday 13 September) as to whether the event will go ahead.

“Public safety and comfort is our priority. Should Swim Serpentine not go ahead on Saturday, all entrants will be offered the option of taking part in 2024 (date to be confirmed) or a full refund of the entry fee they paid. Thank you for your understanding.”

A further post on Wednesday said: “We have analysed the latest test results with experts and stakeholders and levels are decreasing.

“As a result, we are now taking further readings tomorrow morning. We realise this update is later than planned and apologise for this.

“We will provide a further update by 6pm tomorrow, however if you are unable to wait for a final decision, you will be able to apply for a refund.”