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:

1. Taking all litter home with you

2. Keeping your dog away from the lake

3. Not using bacon for crab bait

4. Donating so that we can keep on testing the water and draining the lake to clear out the mud