Good bathing water quality

On Wednesday 7th August 2019, a sample of water was taken from Clevedon Marine Lake.  The results indicate that the water quality in the lake is ‘GOOD’, as stated for Coastal and Transitional waters in The Bathing Water Regulations, 2013.

Fresh sea water from the Severn Estuary is next expected to spill over into the lake between 15th – 18th August 2019; these tides are not big enough to fully refresh the lake, simply freshen the water.

POOR WATER QUALITY ADVISORY

A sample was taken from Clevedon Marine Lake on Monday 22nd July and the results indicate that the water quality in the lake is currently poor.

Test results are shared to allow lake users to make an informed decision about entering the water.  Anyone choosing to swim is advised to wear ear plugs and goggles to protect against infection.  All visitors having contact with the lake water are advised to wash or cleanse hands before eating.

The sample taken on 22nd July showed raised levels of enterococci, a naturally occurring bacteria normally present in sea bathing waters.  With lots of people enjoying the lake, sediment from the lakebed has been stirred up.  Combined with storm run-off and the hot weather, bacteria levels have risen.  Although UV in sunlight kills off harmful bacteria, it is only effective at surface level where the light can penetrate.

It is recommended that the public do not swim in the lake until the water has refreshed.  The lake will be drained on Wednesday 31st July so that it can refresh that evening at around 7pm with water from the Severn Estuary – and repeatedly during the next sequence of overtops between 31st July and 5th August.

The water quality will be retested on 7th August, after the overtops.

ADVICE AGAINST BATHING

Swimming in Clevedon Marine Lake is NOT ADVISED until further notice.

A sample was taken from Clevedon Marine Lake on Monday 22nd July and the results indicate that the water quality in the lake has decreased.

The lake will be drained on Wednesday 31st July so that it can refresh with water from the Severn Estuary, then repeatedly during the next sequence of overtops between 31st July and 5th August.

The penstocks will be opened around 8am on 31st July, and the lake should refill any time after 6pm.  Volunteers will be cleaning in and around the lake from 10.30am on 31st July.  Refills have become a popular spectacle to watch – as 30 million litres of sea water gushes over the seawall into the lake.

The water quality will be retested on 7th August, after the overtop.  Updates on the water quality in Clevedon Marine Lake are shared here.

There’s always lots to do at the lake in terms of litter picking, cleaning, muscle work and site management, so if you can spare any time to help out, please contact volunteer@marlens.org.uk

Do your bit for water quality

Clevedon Marine Lake is a much-loved community asset.  Lake users can follow six simple steps to help keep the water quality good in the lake:

  • No dogs lakeside.
  • Use the public toilets next to the arcade.
  • Use crabbing bait like bacon sparingly and clean up any scraps.
  • Not swim when unwell.
  • Use the drinking tap and freshwater shower adjacent to HM Coastguard Clevedon rescue station.
  • Drop £1 in one of the donation boxes every visit, to help pay for water quality testing and lake care.

During the warm summer months, when the lake is heavily used, the water quality in Clevedon Marine Lake is sampled before and after each series of overtopping tides (approximately those over 12.5m) to provide a baseline health check.  The test results are shared to allow lake users to make an informed decision about entering the water.

Poor bathing water quality test results occur from time to time.  The causes include:

  • A prolonged warm spell. Although UV in sunlight kills off harmful bacteria, it is only effective at surface level where the light can penetrate.
  • Heavy usage stirring up sediment from the lakebed.
  • Heavy rainfall causing run-off into the Severn Estuary, entering the lake on overtopping tides.
  • Contamination from human or dog waste.

Clevedon Marine lake is a semi-natural environment.  It is a living space filled by sea water from the Severn Estuary.  Faecal coliforms are present all around us and inside us.  They live in our gut.  Mammals (including humans), fish and birds produce them all the time.  Faecal coliform bacteria can enter aquatic environments through direct discharge of waste from these species, from agricultural and urban storm runoff, and from human sewage.

There is a year-round ‘NO DOGS’ order in place at Clevedon Marine Lake and the splash pool for public health protection, to reduce the risk of unfriendly bacteria draining into the lake.  A single gram of dog waste can contain millions of faecal coliform bacteria, known to cause cramps, diarrhoea, intestinal illness, and serious kidney disorders in humans.  Faecal coliform bacteria can also present as eye or ear infections.

Updates on the water quality in Clevedon Marine Lake are shared here.  If a poor result is reported, it is recommended that the public do not swim in the lake until the water has refreshed and been retested.  People may choose to use the lake at their own risk in the meantime.  Any swimmers doing so are advised to wear ear plugs and goggles to protect against infection.  All visitors having contact with the lake water are advised to wash hands before eating.

In addition, the water quality in the Severn Estuary, which refills the lake, is monitored regularly by the Environment Agency throughout May to September, with samples taken from Clevedon Beach adjacent to Clevedon Marine Lake.  Poor water quality warnings are issued on-line – and the most recent water quality test results also can be checked.

 

Excellent bathing water quality

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.

Ragworm spawning

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.

 

 

Excellent bathing water quality

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.

Excellent bathing water quality

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.

Refreshing news

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