The bay is long, sandy and backed by sand dunes. It is located 4 kilometres south west of Porthmadog. The area is designated as the Lleyn Peninsula and the Sarnau Special Area of Conservation and Tiroedd a Glannau Rhwng Criccieth ac Afon Glaslyn Site of Special Scientific Interest. The water quality sample point is located south of the caravan park.
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.
In the catchment of Craig Ddu, there are numerous storm, emergency and surface water outfalls in and around the estuary which have the potential to affect the bathing water.
These protect domestic properties in Craig Ddu from being flooded by sewage during heavy rainfall. However, sewer overflows operating during and following periods of heavy rain can result in a deterioration in the quality of the water within the estuary and at Craig Ddu bathing water.
A project known as Event Duration Monitoring (EDM) was undertaken 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. One CSO near Craig Du Beach Central was included in the project.
Natural Resources Wales has developed a good working relationship with Dŵr Cymru Welsh Water and liaises regularly to identify problems that could affect bathing water quality.
Natural Resources Wales and Gwynedd County Council worked together to improve the bathing water quality at Craig Ddu over a number of years. The local authority, Gwynedd Council, regularly clear the strandline on this beach between May and September.
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. There are no known misconnections in the Morfa Bychan area.
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 main fresh water input at Craig Ddu beach is the estuary where the River Dwyryd merges with the River Glaslyn. This drains a largely agricultural catchment. There is also some small industry and a number of tourist facilities (retail/accommodation) within the catchment. These watercourses could be a source of reduced water quality, after heavy rainfall.
A modern sewage treatment works is installed at Morfa Bychan. Secondary biological treatment is carried out here before discharge through a 1.5 kilometre long sea outfall. Porthmadog Sewage Treatment Works also has secondary treatment and discharges to the Glaslyn estuary, which helps protect 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 Craig Du Beach Central, data are available for the four year assessment period from 2020-2023. Sewage debris was not observed at this bathing water. 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 the majority of the time and in greater amounts on less than ten per cent of occasions. Oil and tarry residues were not noted at this site.
The salt marshes of the Dwyryd Estuary are used for sheep grazing. As a result, sheep faeces can be picked up by the tide during spring tides and storm events and left on the beach at Craig Ddu by the outgoing tide. This can result in false reports to Natural Resources Wales of sewage on the beach.
Most discharges at Craig Ddu ar to the public mains sewer, and therefore pose little risk to bathing water quality. There are other private discharges in the area for both sewage and trade discharges, but these are for discharges to soakaway rather than to surface water. Poorly maintained private sewage treatment facilities could be a source of pollution, therefore the registration of all private sewage systems in Wales was required by 30 June 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 were identified in the catchment that were not on mains sewerage, Natural Resources Wales endeavoured to ensure registration was made.
The natural drainage (hydrological) catchment area surrounding the bathing water is urbanised, with the town of Porthmadog located on the lower reaches of the Glaslyn. This contains a number of retail and light industrial units. The upper reaches of both the Glaslyn and the Dwyryd, which merge in the estuary, are mainly agricultural. There are also a number of low lying salt marshes in the area. These marshes are grazed by sheep. During particularly high tides and/or a strong onshore wind, sheep faeces can be washed off these marshes and deposited on beaches around the area. This tends to happen at least once every season, usually at the time of the August high tides, and has a high potential to cause the next sample taken from the beaches to have poor water quality.
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.
