Located on the west coast of Anglesey, between Trearddur Bay and South Stack on Holy Island, the beach is a small sandy, sheltered cove. Porth Dafarch is located within the Anglesey Area of Outstanding Natural Beauty and the Holy Island Coast Special Area of Conservation / Special Protection Area and Site of Special Scientific Interest. The water quality sample point is located at the centre of the bay.
Investigations will be undertaken where and when necessary e.g. where there are elevated bacterial results in the bathing water that cannot be simply explained due to weather conditions.
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. A small stream drains onto the beach under the main road. This drains from the main catchment. Bacterial surveys have been undertaken on this stream. There is a potential for some bacterial input from diffuse agricultural sources associated with grazing in the fields upstream of the beach.
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 Porth Dafarch, data are available for the four year assessment period from 2020-2023. Sewage debris was not observed at this bathing water. Animal faeces was not noted at this site. Trace amounts of litter were observed at the bathing water between twenty and thirty percent of occasions. Oil and tarry residues were not noted at this site.
There are a number of caravan parks in the catchment, which have private sewage treatment systems. These discharge to ground and consequently do not present a risk to surface water and bathing water quality. Poorly maintained private sewage treatment facilities could be a source of pollution. There is a requirement for all private sewage system operators/owners in Wales to register for an exemption as is the requirement since 2012. The primary aim of this exercise was 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. Agricultural land use, mainly pasture and rough grazing predominates. The land behind the beach is relatively flat, with isolated dwellings scattered throughout the catchment, in addition to several caravan sites located north of the beach. A small stream drains onto the beach, from under the main road.
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.
