Sennen Cove is 1.6 kilometres northeast of Lands End in Cornwall. It is a large sandy
beach resort, approximately 940 metres wide, backed by sand dunes. There are two small
streams that flow onto the beach and disperse over the sand.
There is an emergency/storm overflow from the Sennen pumping station, that discharges
to the sea approximately 600m west of the Environment Agency monitoring point. The
operation of the overflow can lead to a temporary drop in water quality at Sennen.
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 for Sennen, which provides secondary
treatment, was completed in 2006. Storm overflow event duration monitoring (EDM) was
installed at the Sennen Cove 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 18% of visits, with 79% 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.
The outfall from Sennen STW, discharges to the sea approximately 600m west of the
Environment Agency monitoring point. 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 Sennen 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 Sennen is approximately 150 hectares. There is a small stream
400m long that discharges close to the Environment Agency monitoring point and disappears
into the sand. A second larger stream 800m long flows through the dunes and onto the
beach 400m north of the Environment Agency monitoring point. Land use is mostly urban
containing a number of small villages with some arable land on the southern slopes.
The catchment lies within part of 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.
