Porthtowan is on the north coast of Cornwall. It is a sandy beach resort, approximately 370 metres wide, backed by cliffs. There is a stream that disperses over the sand in the centre of the beach.
There is an emergency/storm overflow from the Porthtowan Beach pumping station, that discharges into the Porthtowan Stream at the beach. The emergency/storm overflow from the Echo Corner pumping station discharges to the Porthtowan Stream 800m upstream of the bathing water. The emergency/storm overflow from the Porthtowan STW discharges approximately two kilometres upstream of the bathing water. The operation of the overflows can lead to a temporary drop in water quality in the Porthtowan Stream and Porthtowan bathing water.
This bathing water is included in the Surfers Against Sewage “Safer Seas Service”. This service can alert you to Combined Storm Sewer Overflow discharges via a phone App and in addition, it includes the Environment Agency Pollution Risk Forecast warnings where they are available. Further details of the service can be found at - http://www.sas.org.uk/safer-seas-service/
Porthtowan sewage treatment works (STW) has provided secondary treatment since 1972. The sewage treatment scheme for Porthtowan, which provides secondary treatment and ultraviolet (UV) disinfection, was completed by South West Water in early 1999. Further upgrades were installed in July 2002.
Storm overflow event duration monitoring (EDM) was installed at the Porthtowan Beach and Echo Corner pumping stations by December 2011.
For the four year (2020-2023) assessment period where data is available, seaweed (macroalgae) was assessed as being sufficient to be objectionable for 11% of visits, with 75% of visits noting the presence of seaweed (macroalgae). This bathing water does not have a history of large amounts of seaweed (macro algae).
For the four year (2020-2023) assessment period where data is available, phytoplankton (microscopic algae) was not assessed as being sufficient to be objectionable, but was observed as being present on 8% of visits. Phytoplankton (microscopic algae) naturally increase in number at certain times of the year. This process is known as a phytoplankton bloom. This bathing water does not have a history of phytoplankton blooms.
The risks to human health from contact, ingestion or inhalation with marine algae that currently occur in UK coastal waters are considered to be low. However, some individuals may be more sensitive and display some reactions.
A common marine algae found in UK coastal waters is Phaeocystis, which is often mistaken for sewage as it forms foam and a brown scum, but it is non-toxic.
There are no active pollution risk forecasts made at this bathing water. However any bathing water has the potential to be affected by a pollution incident and if this occurs a pollution risk warning with associated advice against bathing will be issued on this website.
Streams and rivers are typically affected by human sewage, animal slurry and runoff from roads. The Porthtowan Stream flows onto this beach. The Environment Agency have monitored the stream between 1989 and 2008, and found that water quality is temporarily worse during and after heavy rainfall.
The outfall from the Porthtowan STW discharges to the Porthtowan Stream approximately two kilometres upstream of the bathing water. This discharge is disinfected and designed to protect bathing water quality.
Environment Agency samplers make observations of litter present on the beach at every visit, this includes assessments of sewage debris, litter and tar. At Porthtowan for the four year (2020-2023) assessment period where data is available, sewage debris was not noted at this site. Litter was not assessed as being sufficient to be objectionable, but was observed as being present on 72% of visits. Tarry residue was not noted at this site.
There are 15 farms in the catchment, most of which are dairy and arable. During and after periods of heavy rainfall, runoff from agricultural areas to the Porthtowan Stream is greatly increased, and the quality of the bathing water may be reduced.
The catchment surrounding Porthtowan is approximately 1,050 hectares. The Porthtowan Stream is approximately four kilometres (km) (6.3km long including tributaries). It flows around the village of Mount Hawke and then through Porthtowan before entering the sea at the beach. The catchment slopes gently from the headwaters in the valley and becomes very steep through Porthtowan to the coast.
The catchment is mostly agricultural with 15 farms and the rural areas are a patchwork of improved grassland and arable land. Urban areas include the villages of Mount Hawke and Porthtowan. Parts of the coast are designated as Godrevy Head to St Agnes Site of Special Scientific Interest (SSSI) and Special Area of Conservation (SAC).
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 England 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 the Environment Agency role to drive improvement of water quality at bathing waters that are at risk of failing higher 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.