On Monday 10th June 2019, a sample of water was taken from Clevedon Marine Lake. The results indicate the water quality is ‘Excellent’ as stated for Coastal and Transitional waters in The Bathing Water Regulations, 2013. The lake water will refresh again with overtopping tides on Sunday, 16th June 2019.
Clevedon Marine Lake is a living space, filled by sea water from the Severn Estuary which is alive with marine life. Due to its high tidal range, the estuary has one of the most extensive intertidal wildlife habitats in the UK, comprising mudflats, sand flats, rocky platforms and islands. These form a basis for plant and animal communities typical of extreme physical conditions of liquid mud and tide-swept sand and rock. The estuary is recognised as a wetland area of international importance, and parts are designated as a Site of Special Scientific Interest.
Thanks to this rich biodiversity, a natural phenomenon occurred at Clevedon Marine Lake on Thursday 23rd May 2019. Visitors noticed clusters of activity under the water’s surface. The pinkish creatures skiting about were spawning ragworm. They look a lot like an underwater millipede. Ragworms emerge from their burrows in late spring and swim freely to spawn at the water’s surface. The event is part of nature’s cycle and will pass as quickly as it started.
The lake remains open for use whilst this natural process works its way through. Some swimmers continue with their laps unfazed; others prefer to wait a couple of days. It’s part of being a semi-natural environment.
The ragworm is highly common around the UK. They live in burrows located between the high tide and low tide points on sandy and muddy beaches and are often found in areas which offer some form of shelter, such as coves, harbours and estuaries. They feed on plankton and other small particles. They are widely used by anglers for bait.
On Friday 28th September 2018, a sample of water was taken from Clevedon Marine Lake after a series of overtopping tides from the Bristol Channel. The results indicate the water quality is ‘Excellent’ as stated for Coastal and Transitional waters in The Bathing Water Regulations, 2013. The lake water will refresh again with overtopping tides from the evening of Sunday, 7th October 2018.
On Monday 17th September 2018, a sample of water was taken from Clevedon Marine Lake after a series of overtopping tides from the Bristol Channel. The results indicate the water quality is ‘Excellent’ as stated for Coastal and Transitional waters in The Bathing Water Regulations, 2013. The lake water will refresh again with overtopping tides from the evening of Monday, 24th September 2018.
You may have read reports about the lake’s water being contaminated by faecal coliform bacteria. So, what does it all mean?
Faecal coliforms are present all around us and inside us. They live in our gut. Mammals (including us humans) and fish produce them all the time. They enter our water courses through normal water run-off. After heavy rains, pollutants on farm land in particular, but also those from our driveways and pavements, get into the water. It is unavoidable.
Clevedon Marine Lake fills naturally on over-topping tides from the Bristol Channel. The Environment Agency monitors water quality on the beach adjacent to the lake during the summer season, and issues poor water quality warnings when they arise.
So, what if the lake refreshes with over-topping water during a period of contamination?
We could of course just drain it out, but that would mean it would not refill until the next sequence of over-topping tides, which could mean the lake’s empty for weeks. When this occurred in August 2018, we decided to leave the lake full and to monitor the quality further. We also posted warnings about the water quality, so people could make an informed decision about entering the water before the drain down and refresh on 8th September 2018. There were no pollution alerts for the Bristol Channel in the run up to the drain down, so the lake should now be full of nice clean water. To make sure, we’ll test it again on 17th September 2018, after the sequence of over-topping tides.
Regular swimmers tend to be sanguine about the water and continue to swim as they have done daily for many years. Faecal coliform bacteria can cause gastro-enteritis symptoms or present as eye or ear infections. If any lake user is at all worried about this they should avoid using the lake until the water quality is confirmed as of at least good quality and keep a look out for updates on Clevedon Marine Lake website and social media channels.
Marlens’ Technical Team