Porthkidney Sands is on the north coast of Cornwall. Porthkidney Sands is a large
sandy remote beach, approximately 1.3 kilometres wide, backed by sand dunes and cliffs.
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/
The sewage treatment scheme for Penzance and St Ives was completed by South West Water
in early 1995. The scheme included extensive sewerage, improvements to intermittent
discharges and the removal of untreated sewage discharges.
Wastewater from St Ives is pumped to Hayle sewage treatment works (STW), where it
receives secondary treatment before its discharge through a 2.7km long sea outfall
west of Godrevy Head. The Hayle STW was enlarged and upgraded in 1995 and again in
2000.
Storm overflow event duration monitoring (EDM) was installed at the Porthgwidden pumping
station and at five intermittent discharges to the Hayle estuary by December 2011.
For the three year (2021-2023) assessment period where data is available, seaweed
(macroalgae) was assessed as being sufficient to be objectionable for 12% of visits,
with 68% 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 three year (2021-2023) assessment period where data is available, phytoplankton
(microscopic algae) was not noted at this site. 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. There are no streams directly affecting this bathing water but it is immediately
next to the Hayle Estuary which can affect water quality during and after heavy rainfall.
Sewage from the Carbis Bay area is pumped to Hayle STW for treatment, and discharges
to the sea four and a half kilometres from the bathing water. This discharge is 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 Porthkidney
Sands for the three year (2021-2023) assessment period where data is available, sewage
debris was not noted at this site. Litter was assessed as being sufficient to be objectionable
for 4% of visits, with 52% of visits noting the presence of litter. Tarry residue
was not noted at this site.
There are farms in the catchment, most of which are dairy and arable. During and after
periods of heavy rainfall, runoff from agricultural areas is greatly increased, and
the quality of the bathing water may be reduced.
There are caravan parks and hotels that are not on the main sewerage system and have
private sewage treatment arrangements. The Environment Agency do not believe these
are a source of pollution to the bathing water. If any concerns arise, the Environment
Agency will investigate and request immediate remedial action from those responsible.
The catchment surrounding Porthkidney Sands is approximately 9,750 hectares. The bathing
water is at the mouth of the Hayle Estuary. The River Hayle is approximately 19km
long rising southwest of Crowan village. It flows west for approximately eight kilometres
and through a steep wooded valley north of the granite high ground at Trescowe Common,
formerly a mining area. The river turns north near the hamlet of Relubbus, and flows
nine and a half kilometres passing St Erth before reaching the Hayle Estuary.
Tributaries to the Hayle Estuary include the Nance Stream, the St Erth Stream and
the Angarrack Stream, which extend the main river network in the catchment to approximately
42km. The Hayle Estuary encompasses a disused port on the east bank and a substantial
area of salt marsh named Lelant Saltings to the west. This is an important habitat
for birds and the Royal Society for the Protection of Birds runs a nature reserve
there. Much of the estuary is designated as a Site of Special Scientific Interest
(SSSI), including the area directly surrounding the bathing water.
Land use is mostly arable with improved grassland concentrated in the southeast of
the catchment. There is a significant amount of urban area concentrated at the coast
including Hayle, Lelant and Connor Downs.
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.
