The water in Clevedon Marine Lake is tested after every series of overtopping tides* from May to September. It is rated against EU bathing water standards as: Excellent, Good, Sufficient or Poor.

Once a tide significantly overtops the lake, any previous lab test result is null and void. When this happens, we will change the status to, Unknown and may qualify it with information about the status of the sea water at that time. This will enable you to make an informed decision whether to enter the water or not.

If from a lab test we know the water quality in the lake to be, Poor, we will fly red flags at each end of the dam wall.

​Poor water quality usually happens when:

• There is a heatwave, loads of people use the lake and water temperatures exceed 22 degrees centigrade;​

• The lake is over-topped with water from the Severn Estuary during a pollution warning.

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When this happens, you should take extra care to keep yourself well.  We recommend:

• ​Avoid swimming if red flags are flying;

• Wear ear plugs when you swim;

• Using hand sanitiser as soon as you leave the water;

• Washing your hands before you eat;

• Showering when you get home;

• Avoiding swimming when the lake is warm and crowded;

• Avoiding swimming when the lake has topped over after a storm.

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You always use Clevedon Marine Lake at your own risk. Please remember that it is a natural body of water that contains sea life.

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*It takes 48 hours to process a water quality test.