The bay is situated on the west coast of Anglesey, south of Holyhead and faces southwest into Caernarfon Bay. The beach is a long stretch of flat sand, with dunes running behind it, with rocky outcrops at either end. The south west area of Rhosneigr and the beach are located in the Anglesey Area of Outstanding Natural Beauty, whilst Llyn Maelog is designated as a Site of Special Scientific Interest. The water quality sample point is located in line with the beach pathway.
Natural Resources Wales works to establish sources of pollution around Rhosneigr. Some of this work is carried out in partnership with Anglesey County 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).
There are 4 intermittent discharges in this catchment. Rhosneigr Sewage Pumping Station discharges directly into the Irish Sea, as does the settled storm discharge from the sewage treatment works, whilst the Ty Croes Sewage Pumping Station further inland discharges into the Crugyll.
A project known as Event Duration Monitoring (EDM) is underway to install telemetry on Combined Sewer Overflows (CSOs) within 2km of a bathing water by 2020 so that Dŵr Cymru Welsh Water (DCWW) know when the CSOs are operating and can work to reduce spills. Two CSOs near Rhosneigr are included in the project.
There are no known misconnections in the catchment.
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.
Algal Blooms can occur at any beach during the bathing season and are usually noticeable by a surface scum. This beach has no history of such blooms.
Streams are typically affected by sewage or industrial run off from further up the catchment. The Crugyll and the stream draining from Llyn Maelog are the main rivers and streams in the bathing water catchment. There is no evidence at present that these represent a risk to bathing 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 Rhosneigr, data are available for the four year assessment period from 2014-2017. Sewage debris was observed in trace amounts on less than ten per cent of occasions. Trace amounts of animal faeces were noted at the site on a minority of occasions. Trace amounts of litter were observed at the bathing water on fifty per cent of occasions and in greater amounts an additional three times. Oil and tarry residues were not noted at this site.
There are currently no known issues with the farms in this catchment that could adversely affect bathing water quality.
All farms were visited around 1999/2000 and remedial actions identified and actioned.
There are a number of caravan parks in the catchment, which are connected to the main sewerage system and consequently do not present a direct risk to bathing water quality. There are also private caravan parks which are not connected to the main sewerage system and have a private sewage treatment arrangement, either to surface water or to ground. It is not believed that these are a source of pollution to the bathing water at present, however if any concerns arise, Natural Resources Wales will investigate and request immediate remedial action from those responsible for any pollution.
Poorly maintained private sewage treatment facilities could be a source of pollution, therefore the registration of all private sewage systems in Wales is 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 properties are identified in the catchment that are not on mains sewerage, Natural Resources Wales will endeavour to ensure registration has been made.
The natural drainage (hydrological) catchment surrounding the bathing water is primarily rural. The village of Rhosneigr dominates the immediate vicinity to the north, with the village of Llanfaelog located to the east. There are several caravan parks in the catchment. The main river in the catchment is the Crugyll, which drains from the east into Llyn Maelog, and consequently onto the beach.
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.