Bigbury-on-Sea South is close to the mouth of the River Avon on the south coast of
Devon. The beach is approximately 450 metres wide, and at low tide Burgh Island is
accessible across the causeway.
There is an emergency/storm overflow from the Warren pumping station that discharges
to the sea at Warren Point 400m from the Environment Agency monitoring point. There
is an emergency/storm overflow from the Bigbury and Challaborough STW that discharges
to the sea at Warren Point 400m northwest of the Environment Agency monitoring point.
The operation of the overflows 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 for Bigbury and Challaborough, which
provides secondary treatment, was completed in 1995. Following concerns over shellfish
quality in the Avon Estuary, South West Water installed an ultraviolet (UV) disinfection
plant at Aveton Gifford sewage treatment works (STW) in 1998. This will have improved
water quality in the estuary near the bathing water. Aveton Gifford STW also received
increased storm storage in February 2002.
Two emergency overflows at Bigbury and Warren Point were improved by April 2003, and
the combined sewer overflow/emergency overflow at Challaborough pumping station was
completed in 2004, and storm overflow event duration monitoring (EDM) was installed
at these sites by December 2011.
Further improvements to protect shellfish water quality are scheduled to be completed
at Brent Mill CSO by June 2021.
The urban area of Bigbury-on-Sea immediately behind the beach is served by a combined
(surface and sewer) system. There are no outfalls from the system onto the beach.
For the four year (2020-2023) assessment period where data is available, seaweed (macroalgae)
was assessed as being sufficient to be objectionable for 3% of visits, with 80% 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. These blooms can discolour the water or form as a foam on the
water. 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.
The Environment Agency makes a daily pollution risk forecast at this site based on
the effects of rain, tide, wind 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 cause a temporary reduction in water quality, we will
issue a pollution risk warning on this website. Water quality will 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 9 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. Bigbury-on-Sea is next to the estuary of the River Avon, and the natural
effects of the wind and tide in the estuary can affect the bathing water quality.
Additionally, there is a stream which flows across the beach to the east of the Environment
Agency monitoring point. The Environment Agency have monitored the River Avon between
1988 and 2009.
The outfall from Bigbury and Challaborough STW discharges to the sea at Warren Point
400m northwest 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 Bigbury-on-Sea
South 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 41% of visits. Tarry residue
was not noted at this site.
The catchment of the Bigbury-on-Sea South bathing water is largely agricultural with
significant areas of land used for livestock, most of which are beef and sheep. During
and after periods of heavy rainfall, runoff from agricultural areas to the River Avon
is greatly increased, and the quality of the bathing water may be reduced.
The homes in Bigbury are all connected to the main sewer system. There is a disused
private outfall from the Hogen (SX6495043950) on the beach at Burgh Island 250m south
of the Environment Agency monitoring point. If any concerns arise, the Environment
Agency will investigate and request immediate remedial action from those responsible.
The catchment surrounding Bigbury-on-Sea South is approximately 15,000 hectares. There
is a tiny stream approximately 200m long which enters the sea at the eastern end of
the beach. The River Avon and its major tributaries (the Bala Brook and the Glaze
Brook) rise on south Dartmoor. The Avon flows for 37 kilometres through the Avon Reservoir,
South Brent, Avonwick, Loddiswell and Aveton Gifford before reaching the estuary mouth
at Bantham and Bigbury on Sea. As the river flows from the open moorland, it has created
steep sided valleys with small enclosures mostly used for small scale livestock farming.
The steep catchment means rain runs off rapidly into the many small streams that feed
the River Avon.
The estuary of the Avon is tidal up as far as the weir at Aveton Gifford, and like
the other estuaries of South Devon, the original deep river valley has been flooded
by sea level rise, to create a wide expanse of water. The catchment is mostly agricultural,
with more than 50 farms.
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.