The bay is located on the south Gower Coast, west of Langland Bay and Mumbles Head. The beach is gently sloping and sandy, with limestone cliffs on either side, backed by a concrete promenade with several seaside shops. The water quality sample point is located at the centre of the bay.
Natural Resources Wales works to establish sources of pollution around Caswell Bay. Some of this work is carried out in partnership with the Swansea Council and Dŵr Cymru Welsh Water.
Inspections are carried out by Natural Resources Wales in partnership with the local authority and the water company. These are carried out pre-season (before the 15th of May) and mid-season, if required (during the bathing water season).
Following several bathing water quality failures in 2008, Natural Resources Wales carried out sampling of the surface water drain and the groundwater stream that enters the sea at Caswell beach. The results of these samples illustrated the surface water drain was polluted. In response, Natural Resources Wales, along with Dŵr Cymru Welsh Water and the Swansea Council, carried out an intensive investigation of the drainage system in the area. A significant number of domestic washing machines, dishwashers, sinks and showers were found to be incorrectly connected to the surface water sewers. The Swansea Council have worked with householders to ensure that all the misconnections have been corrected. Further work needs to be done to identify other sources of pollution which tend to occur in very heavy rainfall when flows emerge onto the beach from the dry river valley.
There is an emergency overflow from the pumping station at Caswell Car Park which can operate if the pumping station breaksdown.
Bishopston Sewage Treatment Works has a storm overflow, which passes through a reed bed, prior to discharging offshore at Brandy Cove.
A project known as Event Duration Monitoring (EDM) is underway to install telemetry on Combined Sewer Overflows (CSOs) by 2020 so that Dŵr Cymru Welsh Water (DCWW) know when the CSOs are operating and can work to reduce spills.
Until 1999, Swansea's sewage was discharged directly to the sea from the Mumbles Headland, less than 1.5 kilometres away. In 1999, Swansea's sewage system was significantly upgraded, when a new Wastewater Treatment System was installed at Fabian Way. This resulted in a vast improvement to the bathing water quality at Caswell.
Recently, Natural Resources Wales has worked with Dŵr Cymru Welsh Water to trace the sources of pollution in the public and private surface water drains of the Caswell catchment.
Natural Resources Wales works closely with the Swansea Council to monitor and improve bathing water quality at Caswell. Meetings are held on a quarterly basis. Investigations and inspections are carried out in collaboration.
Natural Resources Wales works with the Swansea Council to identify and rectify household misconnections.
Modern sewerage systems have two separate systems, one takes foul sewage to sewage treatment, the other takes rainwater runoff through surface water drains to rivers, lakes and the sea. Misconnections occur when waste water pipes are plumbed into surface water drains instead of the foul water sewerage system. This can give rise to pollution when the waste water is discharged directly to the environment through the surface water drain. For example, a washing machine or toilet may be incorrectly plumbed so that it discharges to the surface drain rather than the foul sewage drain.
Phytoplankton (microscopic algae) naturally increase in number at certain times of the year. This process is known as a phytoplankton bloom. These algal blooms can occur at any beach during the bathing season and are usually noticeable by a surface scum. This beach has a history of such blooms.
Due to the limestone geology in the area, there are no streams on the surface of this catchment. However, there is a significant groundwater stream, which enters the sea at Caswell Beach near to the sample point. Additionally, during periods of very heavy rainfall, groundwater from the Caswell Valley emerges from a ‘sink hole’ at the bottom of the car park, flowing on to the beach. Some rain which falls onto the land also percolates through the rock fissures and reappears on the beach in the form of springs.
There are no sewage treatment works outfalls at Caswell. Bishopston Sewage Treatment Works discharges offshore approximately 500 metres west of Caswell Beach, at Brandy Cove. The effluent is disinfected by ultra-violet light, to protect the water quality.
Natural Resources Wales samplers make visual observations of the beach at every visit. This includes assessments of sewage debris, animal faeces, litter and oil or tar. At Caswell Bay, data are available for the four year assessment period from 2015-2018. Sewage debris was observed in trace amounts on between twenty and thirty per cent of occasions and in greater amounts on one occasion in August 2015. Animal faeces was noted in trace amounts on a minority of occasions and in greater amounts on one occasion in August 2018. The sampler noted that it was seagull faeces and that there were a lot of feathers present at the high-tide line. Trace amounts of litter were observed at the bathing water the majority of the time and in greater amounts on less than ten per cent of additional occasions. Oil and tarry residues were not noted at this site.
Poorly maintained private sewage treatment facilities could be a source of pollution, therefore the registration of all qualifying private sewage systems in Wales was required by 30 June 2012. The primary aim of this exercise is to provide increased protection for the environment and sensitive features such as bathing water beaches. Where discharges from properties are identified in the catchment that are not on mains sewerage, Natural Resources Wales will endeavour to ensure registration has been made, unless already a permitted discharge.
The natural drainage (hydrological) catchment surrounding the bathing water is a steep limestone valley. There are no streams or rivers running on the surface of the valley bed. The rocks in the area are limestone, meaning the rain which falls onto the land can percolate through the rock fissures and onto the beach. During periods of very heavy rainfall, groundwater emerges from a ‘sink hole’ at the bottom of the car park and flows onto the top of the beach. There is a significant groundwater stream, which flows onto the beach, next to the sample point. Some rainwater falling within the catchment is directed into a surface water drain, which flows onto the beach.
The area is relatively urban and residential, with a chalet park to the east and a car park to the rear, which backs onto Bishop’s Wood Local Nature Reserve. There is also grazed common land at the top of the catchment.
Seaweed (macroalgae) and phytoplankton (microscopic algae) are a natural part of the marine and freshwater environment. Below we note whether these have been recorded in quantities sufficient to be a nuisance.
The majority of sewers in Wales are “combined sewers” and carry both sewage and surface water from roofs and drains. A storm overflow operates during heavy rainfall when the sewerage system becomes overwhelmed by the amount of surface water. The overflow prevents sewage from backing up pipes and flooding properties and gardens. An emergency overflow will only operate infrequently, for example due to pump failure or blockage in the sewerage system.
Heavy rain falling on pavements and roads often flows into surface water drains or highway drains, ending up in local rivers and, ultimately, the sea. The quality of bathing water may be adversely affected as a result of such events.
It is Natural Resources Wales' role to drive improvement of water quality at bathing waters that are at risk of failing European standards. It is natural for water to run off the land to the sea. Water quality at a bathing water is dependent upon the type and area of land (the catchment) draining to the water and the activities undertaken in that catchment. The following sections serve to highlight potential sources of pollution, conditions under which they may arise and measures being put in place to improve water quality.