Polurrian Cove is on the south coast of Cornwall. It is a rural sandy cove, approximately
330 metres wide, surrounded by rocks and steep cliffs. A stream flows onto the beach
and disperses over the sand.
There is an emergency overflow from the Polbream pumping station, that discharges
to the sea 270m from the Environment Agency monitoring point.
There is an emergency overflow from the pumping station at Polurrian Cove Public Conveniences,
that discharges to the Mullion Brook 160m from the Environment Agency monitoring point.
The operation of the overflows can lead to a temporary drop in bathing water quality.
The South West Water scheme for The Lizard sewage treatment works (STW), which provides
secondary treatment, was completed in September 2005. Sewage from the Mullion catchment
is pumped to The Lizard STW for treatment, and discharges to the east of Lizard Point.
Storm overflow event duration monitoring (EDM) was installed at the Mullion Transfer
pumping station by April 2012.
For the three year (2021-2023) assessment period where data is available, seaweed
(macroalgae) was assessed as being sufficient to be objectionable for 16% of visits,
with 76% of visits noting the presence of seaweed (macroalgae). This bathing water
beach often has patches of seaweed (macroalgae).
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 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. The Pollurian Stream (also known as the Mullion Brook) flows onto this
beach. The Environment Agency have monitored the stream between 1990 and 2008, and
found that water quality is temporarily worse during and after heavy rainfall.
Environment Agency samplers make observations of litter present on the beach at every
visit, this includes assessments of sewage debris, litter and tar. At Polurrian Cove
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 60% of visits noting the presence of litter. Tarry residue
was not noted at this site.
There are very few farms in the catchment. During and after periods of heavy rainfall,
runoff from agricultural land is greatly increased, and the quality of the bathing
water can be reduced.
The catchment surrounding Polurrian Cove is approximately 80 hectares. The Mullion
Brook is a small stream approximately 800m long which flows from the village of Mullion
to the beach. The catchment slopes gently from north to south and becomes steeper
at the coast. The steep slopes in the lower catchment mean rain runs off rapidly into
the stream.
The catchment is mostly taken up by the village of Mullion village, and there is some
arable and grass land closer to the coast. A section of the Lizard Special Area of
Conservation (SAC) and Baulk Head to Mullion Site of Special Scientific Interest (SSSI)
can be found on the coast and lower reach of the stream. 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.
