Trevone Bay is on the north coast of Cornwall. It is a fairly remote sandy beach,
approximately 170 metres wide, in a sheltered cove. There is a stream which flows
across the beach to the sea.
There is an emergency/storm overflow from the Trevone pumping station that discharges
to the sea 450m from the Environment Agency monitoring point. The operation of the
overflow can lead to a temporary drop in bathing water quality.
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 South West Water sewage treatment scheme known as the Trevone Scheme collects
sewage from the various settlements around the Camel Estuary. It is split into two
schemes centred on the Porthilly sewage treatment works (STW) (East Bank Scheme),
and a works at Trecerus near Padstow (West Bank Scheme).
Trecerus STW was completed for the 1997 bathing season with chemically assisted sedimentation
and ultraviolet (UV) disinfection for sewage from St Merryn, Trevone and Padstow.
Improvements were also made to the sewerage in Padstow, St Merryn, Harlyn and Trevone
at that time. The treatment was subsequently upgraded to full secondary treatment
and UV disinfection by April 2004.
Storm overflow event duration monitoring (EDM) was installed at the Trevone pumping
station by April 2011.
The urban area of Trevone immediately behind the beach is served by a combined (surface
and sewer) system. There are no outfalls from the system on the beach.
For the four year (2020-2023) assessment period where data is available, seaweed (macroalgae)
was not assessed as being sufficient to be objectionable, but was observed as being
present on 80% of visits. This bathing water does not have a history of large amounts
of seaweed (macro algae).
Wrongly connected domestic waste water pipes can affect the bathing water quality.
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.
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 3% 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.
This bathing water is subject to short term pollution procedures. The Environment
Agency makes a daily pollution risk forecast at this site based on the effects of
rain, tide and seasonality on bathing water quality. These factors affect the levels
of bacteria that get washed into the sea from livestock, sewage and urban drainage
via rivers and streams and how they disperse.
When these factors combine to make short term pollution likely we issue a pollution
risk warning on this website and the beach manager will display a sign advising against
bathing at the bathing water. After a short term pollution event, levels of bacteria
typically return to normal after a day or so but it’s possible to have several warning
days in a row. Details of the work to reduce the sources of bacteria at this bathing
water are detailed in this profile.
In 2023 2 pollution risk warnings were issued for this bathing water.
All bathing waters have the potential to be affected by a pollution incident and if
this occurs a pollution risk warning will be issued with associated advice against
bathing on this website.
Streams and rivers are typically affected by human sewage, animal slurry and runoff
from roads. The Trevone Stream flows across this beach. The Environment Agency have
periodically monitored the stream and found that water quality is temporarily worse
during and after heavy rainfall.
The outfall from the Trecerus STW discharges to the sea approximately 2.3km to the
west of this 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 Trevone Bay
for the four year (2020-2023) assessment period where data is available, sewage debris
was not noted at this site. Litter was assessed as being sufficient to be objectionable
for 2% of visits, with 48% of visits noting the presence of litter. Tarry residue
was not noted at this site.
The catchment surrounding Trevone Bay is approximately 340 hectares. The Trevone Stream
is approximately 2.2 kilometres (km) (3.2km long including tributaries) and flows
through farmland and the village of Trevone before entering the sea at the beach.
This is a relatively gently sloping catchment with no steep valleys or headwaters.
Land use is mostly agricultural, with just two or three farms, arable land and some
improved grassland. The urban areas are the village of Trevone and a small industrial
estate at the top of the catchment. The Trevone Bay Site of Special Scientific Interest
(SSSI) is on the coast, and the catchment is in the Cornwall Area of Outstanding Natural
Beauty (AONB).
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.
