Carbis Bay beach is on the north coast of Cornwall. It is a privately owned sandy
beach resort, approximately one kilometre wide, backed by sand dunes.
There is an emergency overflow from the Porthminster Point pumping station that discharges
670m northwest of the Environment Agency monitoring point. The operation of the overflow
can lead to a temporary drop in bathing water quality.
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 Porthminster Point
pumping station by April 2011.
For the four year (2020-2023) assessment period where data is available, seaweed (macroalgae)
was assessed as being sufficient to be objectionable for 7% 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 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 is a very small stream flowing onto this beach which may reduce
bathing water quality during or after periods of heavy rainfall due to run off from
the surrounding urban area.
Sewage from the Carbis Bay area is pumped to Hayle STW for treatment, and discharges
to the sea five kilometres northeast of the bathing water. This discharge is designed
to protect bathing water quality.
There is a disused outfall from Carbis Bay.
Environment Agency samplers make observations of litter present on the beach at every
visit, this includes assessments of sewage debris, litter and tar. At Carbis Bay 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 36% of visits. Tarry residue was not noted at
this site.
The catchment surrounding Carbis Bay is approximately 200 hectares. The Carbis Bay
Stream is an intermittent stream approximately 1.6km long that discharges at the bathing
water. The steep catchment means rain runs off rapidly into the stream. The Hayle
Estuary enters St Ives Bay approximately two kilometres east of the beach.
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 urban from the coastal settlement of Carbis Bay. In the upper catchment
there is some improved grassland and arable land.
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.