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Stay safe in the cold

As we go into the winter season, here is some information about cold water swimming and water quality at Clevedon Marine Lake.

Be bold in the cold

It’s no secret that cold water dipping has amazing mental health and wellbeing benefits. Over the past year, especially since Covid struck, we have seen so many more people trying out winter swimming.

But it is an extreme sport with very real risks to your health, even death. Last year, we saw lots of people getting ill because they didn’t know these risks. Please make sure you learn how to swim safely before trying out cold water swimming:

Winter water quality

We stop testing the water quality in Clevedon Marine Lake from October 1st. Why? Because cold water kills bacteria. Also, fewer people use the lake than in the summer and that means the water is likely to remain good or excellent. Our last test of the summer on September 27th 2021 showed that the water quality was excellent.

The only time to be careful is when Surfers Against Sewage puts out a pollution warning in the sea AND this coincides with the lake being topped over (high tide height >12.6m).

Happy winter swimming. Stay safe.

Competition time!

Fancy seeing your artwork on a t-shirt? We’re launching a brand new competition to design a t-shirt for Clevedon Marine Lake!

We’re launching a brand new shop to help raise funds for Clevedon Marine Lake and to celebrate, we’re inviting you to add your designs. One lucky winner will get their design printed on a t-shirt of their choice, and nine runners up will have their t-shirts added to the shop.

How do I enter?

To enter, you need to fill in this form and email your design to Your design should be saved in PNG format and should be 2500px by 3500px (sRGB). Think simple, eye-catching designs and fun slogans that would appeal to swimmers, volunteers, kayakers and paddleboarders. Children may enter too, but they need permission from their parent or guardian.

When will the winner be announced?

The competition closes at midnight on Sunday, 7th November. Once the winners have been picked by the trustees who look after the lake, you’ll be able to see the designs in our shop.

Our shop is hosted by Teemill. Everything you buy is printed on-demand using only organic materials and renewable energy.

Join in! 24-hour relay challenge

Are you ready for a challenge? Working with Level Water, we’ve set up something big, something brilliant…!

You’ve stumbled upon the newest, hardest and most ridiculous swim out there. This is the kind of swim that makes your friends say, ‘Of course you are, classic you doing something totally unbelievable’.

Sound familiar? Welcome to your next challenge. A 24-hour swim relay where you and up to seven others swim for an hour each until 24 hours is up. 

At this point, it’s probably a HELL YES or a straight-up no.

If you’re not sure by now, then it’s probably not for you. It’s for those who seek out the extreme and know when not to quit. Who thrive in the challenge and know that if you keep going, anything is possible. Who are determined and know when to just dig in and swim. It’s not about winning. Because the most satisfying point isn’t the end. It’s knuckling down during a night swim, supporting your friends, the feeling of dawn. It’s the challenge, not just the finish line.

They say the night is darkest before the dawn. Are you willing to find out?…….while swimming?

What’s this all about? Give me the basics…

Ok, so basically you gather a team of 4 swimmers who love an epic challenge and head to Clevedon Marine Lake on Saturday 11 September 2021. Then, at 11am on the dot, one of you jumps in and swims for an hour. It’s not a race. There’s no finish line. You just swim for an hour. Then the next swimmer, then the next until 24 hours is up and you’re shattered, but elated that you’ve just completed one of the hardest swimming challenges out there. 

Ok, I’m intrigued. What do you mean it’s not a race? 

I mean you’re not competing against anyone but yourself. It’s an endurance event and there are no winners medals (although you’ll probably get a ‘you’re incredible’ medal from Level Water). The challenge is how far you can push yourself through the tiredness. Through the cold. How you can support each other through the harder hours.

Even though it’s not a race, it would still be great to be able to track how far each team swims in the 24 hours. If you have a couple of people who can come along to help you count that would be great otherwise you can count for each other.

This sounds incredible. What kit would I need?

The most important thing to bring along is warm clothes because you will get cold. And make sure to bring plenty of food and drink for the duration. You’ll also want to try and grab a nap in between your swims so sleeping bags would be useful. You’ll have three hours between your swims so there’s plenty of time to nip off for a nap. 

You will need a tow float and light so we can keep an eye on you at night. We can help you source them if you don’t already have them.

It’s up to you what you wear to swim in. You can wear a wetsuit if you like or brave it in a costume. You can use flippers or hand paddles to help you along.

o it’s £200 to enter a team. Is there a fundraising target? 

It’s £200 per team but you don’t need to pay for it yet because, chances are, you don’t know who’ll be swimming with you. We’ll ask each team member to make a £50 donation onto their JustGiving page once they’ve signed up. For that £50 you’ll each get a Level Water piece of kit, some refreshments on the day and total support from us throughout.

With the fundraising, the team captain will set up a team page on JustGiving with each team member then creating their own page connected to that team. It’s pretty easy and we’ll help you sort it out. Everyone will have a £200 fundraising target and you’ll get rewards for how much you raise.

Is it safe?

There’ll be plenty of measures in place to make sure all swimmers are safe. From canoes out on the lake, lifeguards on the side, first aid close by and plenty of motivation and encouragement from us.

As mentioned above, please bring a tow float, light that you can swim with in the bag or on your goggles and a whistle. This is so we can easily spot you at night and you can draw attention to yourself if you get into any difficulties.

Sign up here!

Red flag: poor water quality

Despite our best efforts, the water quality in Clevedon Marine Lake is still poor. On July 21st 2021 we took a water sample from the lake that showed a higher level of bacteria than is acceptable for bathing water. We closed the lake and drained the water from the lake so that it could be topped over with fresh water from the sea. But, on July 27th, the sample was still poor against EU bathing water standards.

Why did this happen?

Water quality drops when one of two things happen:

  1. We have a heatwave. Lots of people use the lake and the water temperature goes up.
  2. The water that fills the lake from the Bristol Channel is of poor quality. This happens when storm sewers are allowed to overflow into the sea and when rain washes farm waste off the fields and into the rivers.

In July 2021 both these things happened. First of all, we had a heatwave. Crowds flocked to the marine lake to cool off. Every human body is alive with bacteria that usually lives harmlessly on our bodies, but this washes off in the water. Add sunscreen, bait for crabs and litter, and the amount of new bacteria in the water goes up. On top of this, many feet stir up the mud at the bottom of the lake blocking the sun’s ultra-violet rays that kill bacteria. Also, the water temperature becomes too warm to kill off the bacteria.

After we drained the lake, it topped over with the sea during a pollution warning. Storm Evert brought with it heavy rain. This meant that run-off from the fields polluted the rivers that run into the sea. Water companies also opened their storm overflow sewers releasing sewage into the sea. To find out more about this issue, read here or check out Surfers Against Sewage.

Can I still swim?

The red flags at Clevedon Marine Lake are flying. This means that we don’t recommend using the lake. If you do decide to swim, kayak or paddle there, please take extra care by:

  • hand sanitising your hands as soon as you get out of the water
  • washing your hands as soon as possible
  • having a shower when you get home
  • avoiding putting your head in the water, or if you do, wearing earplugs and goggles.

If you are immuno-compromised or pregnant, please seek medical advice before you swim. Here is a good guide to keeping in good health in open water.

Myth busting water quality

There are lots of myths and rumours on social media about the water quality in Clevedon Marine Lake, so we thought that we’d set the record straight.

Myth #1: The water in Clevedon Marine Lake is dirty

We test the water regularly from April to October. Since we started testing, 80% of the results have been good or excellent. To put that another way, we have had 8 weeks of poor water quality since summer 2018. The lake is usually cleaner than the sea and rivers.

Myth #2: The lake is full of dog poo

‘I heard that when the lake was drained they found a load of dog poo bags at the bottom.’ This is one of the best untruths we saw on Facebook. This didn’t happen. It’s true that bacteria on animals and humans get into the water, which is why we don’t have dogs in or by the lake. But, poor water quality is caused by a combination of four things:

  1. Warmer water temperatures. The lake is quite small and can reach 30 degrees centigrade, which is the perfect temperature for bacteria.
  2. More people in the lake. People bring germs.
  3. Mud getting stirred up. When people stir up the mud in the bottom, it blocks the sun’s UV rays which would naturally kill bacteria.
  4. Big gaps between over-topping tides. The tide must be higher than 12.6 metres to refresh the lake.

Myth #3: The lake’s brown colour is dirt.

Clevedon has the highest tidal range in the world. This means that the silt in the sea never settles. This doesn’t mean that the water’s dirty, but it does cause problems. The mud settles on the floor of the lake where it becomes compacted and stagnant. We drain the lake every March and October for a week to dig out as much mud as we can — this costs £10k a year!

Myth #4: Diet cola kills germs from wild swimming

This doesn’t say much for diet cola, but some swear that it kills bugs from open water. However, it is a good plan to wash after you swim in wild (not treated with chlorine) lakes, pools and the sea. Wash your hands before you eat and have a shower when you get home.

You can help us

Clevedon Marine Lake is run by volunteers. You can support our charity to keep the water clean by:

  • Taking all litter home with you
  • Keeping your dog away from the lake
  • Not using bacon for crab bait
  • Donating so that we can keep on testing the water and draining the lake to clear out the mud

Join in: swim challenge

Fancy a challenge? On the weekend of 14/15 August, you can set yourself any swimming challenge you like. It might be a distance — maybe you’ve always wanted to swim 1km, 5km or even 10km. It might be swim in somebody’s memory or a swim in a funny costume. You can do it on your own or as part of a team.
Whatever you choose, this is your chance to be a part of a national challenge and raise money for a fantastic cause at the same time. You’ll get a free event swim cap and have the chance to win some amazing prizes.

What’s the charity?

The challenge is set up by Level Water and lakes all across the UK are taking part. Level Water is a national charity that provides bespoke, 1-1 swimming lessons to children with disabilities. They currently work in 80 pools and provide 20,000 lessons to 500 children, but this is all at risk. Their income has been hit hard with the cancellation of 2020 and 2021 events, which is why they’ve teamed up with the Outdoor Swimming Society to run ‘Lakes for Level Water’ for a second year giving you the chance to be part of an incredible challenge and giving Level Water hope of survival.

What’s more, Clevedon Marine Lake will get 20% of all the funds raised. We are raising money to build a disabled changing room and toilet by the lake, and to store the disabled hoist that we raised money to buy with our winter swimming challenge. We believe in providing access for all to Clevedon Marine Lake and opening up opportunities for more people to enjoy the benefits of water activities, which is why we’re so happy to be working with Level Water.

Want to take part?

Go to and register.

Join our fundraising team and start raising money. There are loads of fantastic prizes to be won!
Please note: the lake will remain open to the public throughout both events. If you’re not taking part, please come and give the swimmers your support! 

Water quality excellent despite crowds

It’s been a busy couple of weeks at Clevedon Marine Lake. From dawn to dusk, people have been arriving in their droves to swim, paddleboard and enjoy being by the water.

Over the last few years, crowds plus warm water temperatures have led to a drop in water quality. But, not this year. We have been taking regular samples to be tested at a local lab and the water quality has remained ‘excellent’.

Safe and fun

Keeping the lake safe and clean is our priority. Every morning, our volunteers clean up litter from the day before. But this hasn’t been easy. Not only have people been leaving lots of litter, but also broken glass and even dog poo. This is dangerous for people with bare feet, children playing and risks affecting the water quality.

You can help

To help us keep our lake clean and safe for everyone, please:

  • take all litter home with you or use the big wheelie bins on the upper promenade
  • don’t bring your dog to the lake
  • avoid single-use plastics where you can
  • don’t bring glass bottles
  • buy wooden crabbing lines
  • keep barbecues off the ground (they damage the concrete when hot)

You can also donate to support our charity’s work or volunteer to help the morning clear-up.

If you’re spot anything that’s broken or damaged, please get in touch. If you’re concerned about anti-social behaviour at the lake you can report it to Avon and Somerset Police here.

Plugging the lake

Clevedon Marine Lake’s technical team came with an ingenious way of fixing a leak this week.

We’d noticed the level of water in the lake dropping, and found a leak next to the sluice gate in the lake wall. Engineers fitted the sluice gate during the 2015 refurb so that we could drain the lake for maintenance. But the pressure of the water inside the lake meant that a small amount was leaking out in between over-topping tides.

That’s when our technical team came with an ingenious but simple plan to stop the gap using sawdust and sand. Tim Clouter, the trustee for Clevedon Marine Lake who looks after the volunteer technical team, realised that sand and sawdust was a time-proven method for blocking leaks. But the challenge was how to get the mixture in the right place.

After chatting through a few ideas, which included Tim diving down in his scuba diving kit or fellow technical volunteer Nick Haliwell going snorkelling, Tim hit upon a very clever hack. “I got the polythene bag that the sand came in and made a quick-release clamp that went on the end,” he said. “We had a pin on a string, and when you pulled the string, the clamp fell off and dumped the mixture in the right place.”

Some of the other volunteers were a bit sceptical of Tim’s idea, but it worked so well that he used the same method to sure up another small leak in the lake wall. Tim then had the job of rescuing a few stranded shrimp who’d been living in the leak on the sea-side of the lake wall and scooping up a bit of sawdust that had got away. But the beauty of Tim’s method is that there was no risk to the lake environment or water quality.

A team of volunteers works hard every single day to look after Clevedon Marine Lake to make it a safe and clean environment for everyone to enjoy. You can support our hard work by donating or volunteering yourself.

You can listen to Tim being interviewed by BBC Radio Bristol here. Please go to 1:17:00 on this clip.

Mud, eels and treasure

Tonnes of mud, wedding rings, Go-Pros, eels and broken glass… If you’ve ever wondered what’s under the water in Clevedon Marine Lake, now you know!

Twice a year Clevedon Marine Lake volunteers open the sluice gates to drain out the water to remove tonnes of silt build-up. With the second-highest tidal range in the world, the Bristol Channel around Clevedon moves too much to let the silt settle on the river bed. Every time the tide tops over the lake’s wall, it deposits the mud that sinks to the bottom and builds up over time. To keep the lake deep enough for swimmers, canoeists and paddle-boarders, we need to get the digger in.

On March 19th we opened the penstock and sluice gate, letting the water in Clevedon Marine Lake slowly drain out.

Then, on Saturday 21st, a working party of around 60 volunteers trawled the lake bed to remove debris, rescue sea creatures and search for missing treasure. Among the treasures found were two GoPro cameras and three rings.

Caspar Clarke was our youngest volunteer to find a ring using the metal detector that he got for Christmas. After his mother posted a photo of 9-year-old Caspar holding the ring on the swimmers’ Facebook page, we managed to reunite it with its owner, Andrew Mitchard.

“I lost my wedding ring while paddle-boarding somewhere in Clevedon Marine Lake last June,” said Andrew. “With the help of a nine-year-old with a metal detector and a bit of social media assistance, it’s only gone and turned up! Nine months at the bottom of the marine lake, and it’s still in reasonable condition. Rumour has it my wife is planning to talk to me tonight! I would like to say thank you to Caspar and all at Marlens.”

Caspar with the ringA lot of people don’t realise that Clevedon Marine Lake is run by a charity and a dedicated team of volunteers. These volunteers don’t just organise clear-ups when the lake is drained; they also litter-pick, clean, mend and even pick up dog poo pretty much every day. They also clean, catalogue and store all items found in the lake with the hope of returning them to their owners.

“Cleaning up the lake was quite fun, especially when we found cool things like eels and rings! I felt really excited and surprised that I actually found something,” said Caspar. “The man was obviously very happy for me to find it, and I was happy because he got his ring back.”

We are now working hard to prepare for what we expect to be a busy summer. We’re putting in two sets of new steps, adding extra water quality tests and redesigning the website and lake signage. This will make it easier than ever to enjoy the lake, keep it clean and safe, and observe social distancing for as long as it’s in place.

We know that fresh air and exercise support our immunity and is good for our mental and physical health, so we don’t want to discourage visitors. But we would ask that people help us keep the lake clean by not bringing their dogs, taking home their litter and that they donate £2 every time they visit.

To donate, please click here or find the white donation boxes around the lake (emptied daily). To become a volunteer, please email

Get stuck in!

Every year, we drain the lake to remove the silt build-up. But this is also our chance to clean seaweed and algae off the steps, fix broken or worn fittings, add new features and facilities… and search through the mud for lost property!

All this work is done by a team of volunteers. And you can help too. On Saturday 20th March, we will meet by the lock-up on the upper-promenade near the coastguard’s hut from 9 am. Or, you can turn up at any point and ask a volunteer in a turquoise tabard what you can do.

The drain down timetable

Friday 19th March:

  • Open penstock, 9-10 am and put out barriers.
  • Close penstock, 7 pm.


Saturday 20th March, 9 am to 6 pm: 

  • Open lower lake penstock to drain out residual water, then close it
  • Search lake bed for lost property and bring anything of value to the shuttered
    shelter to be recorded
  • Remove debris from lake bed. Check the edges carefully for broken glass
  • Scrub weed from steps and handrails, using wire brushes
  • Tighten bolts
  • Pressure wash splash pool and slipway

Monday 22nd to Friday 26th March:

  • Digger to remove silt from the lake bed. No public access during this time.

Friday 26th March 6 pm onwards (after digger finishes):

  • Re-position any buoys which have been disturbed by the dredging.

Saturday 27 March 9 am-12

Note: High tide (6 am, 6.15 pm) may start to refill the lake depending on the weather.

  • Clean mud off the lower promenade
  • Remove mud left by the digger on the ramps and upper promenade
  • Put up flags on all the remaining flagpoles
  • Remove barriers

The lake will refill from the overtopping tide at 7.30 am on Sunday 28th March.

Voluntary work is allowed under government guidance. Please make sure that you keep socially distanced, bring your hand sanitiser and your own gardening or rubber gloves. Please don’t come if you or anyone in your household has symptoms of coronavirus, or if you have been told to self-isolate.

All ages and abilities are welcome. Volunteering work is done at your own risk.

Can’t help this time?

Please consider donating to Marlens, the charity that looks after the lake.