There is an emergency/storm overflow from Porthgwidden pumping station, that discharges
to the sea approximately 120m east of the bathing water. The operation of the overflow
can lead to a temporary drop in bathing water quality.
In the past Porthgwidden bathing water was affected by the untreated outfall at Bamaluz
Point. The outfall was removed as part of the South West Water scheme for Penzance
and St Ives completed 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 2.7 kilometre (km) 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 by December 2011.
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 68% of visits. 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.
Sewage from the St Ives area is pumped to Hayle STW for treatment, and discharges
to the sea four and a half kilometres northeast of 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 Porthgwidden
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 21% of visits. Tarry residue was not noted at
this site.
The small catchment surrounding Porthgwidden is approximately 1.7 hectares. There
are no streams discharging directly to the beach. Land use is evenly split between
coastal grassland and urban.
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.
