Swanage Central is within Swanage Bay on the Dorset coast. It is a sandy beach resort,
approximately 960 metres wide surrounded by hills, and close to the promenade and
town.
There is a storm overflow from the Swanage Shore Road (O/S Nursing Home) CSO, which
discharges to the Ulwell Stream 340m from the beach. There is also a high level emergency/storm
overflow from the Swanage STW Tunnel, which discharges to the sea at the slipway 550m
south of the Environment Agency monitoring point.
There is a storm overflow from the Swanage STW Tunnel at SZ0423078660, discharges
to the sea 170m east of Peverill Point.
The operation of the overflows can lead to a 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/
A resewerage programme in North Swanage was completed by Wessex Water in 1997. Stormwater
storage tanks were built at Ulwell resulting in a significant reduction in the frequency
of spills from combined sewer overflows (CSO) to the Ulwell Stream. The construction
of a tunnel sewer was completed in March 1999. This resulted in the removal of CSO's
to the Swan Brook, and a significant reduction in the spill frequency of other CSOs
in the Swanage sewerage catchment.
The Wessex Water sewage treatment scheme for Swanage, which provides secondary treatment
and microfiltration, was completed in July 2000.
The urban area of Swanage immediately behind the beach is served by a combined (surface
and sewer) system. There are no outfalls from the system onto the beach. Surface water
can flow into the Swan Brook and Ulwell Stream from urban areas and highway drains.
This can affect stream water quality, particularly after periods of rainfall.
For the four year (2020-2023) assessment period where data is available, seaweed (macroalgae)
was assessed as being sufficient to be objectionable for 6% of visits, with 84% of
visits noting the presence of seaweed (macroalgae). This bathing water does not have
a history of large amounts of seaweed (macro algae).
Wrongly connected domestic waste water pipes can also affect the stream water quality.
We have checked the local sewerage system for misconnections. We are working with
Wessex Water to identify and rectify any problems.
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 assessed as being sufficient to be objectionable for 2% of
visits, with 5% of visits noting the presence of phytoplankton (microscopic algae).
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, 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 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 4 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 Swan Brook and Ulwell Stream enter the sea at the beach. The Environment
Agency have regularly monitored the Swan Brook since 1994, and the Ulwell Stream since
1996. This monitoring has now stopped.
The outfall from the Swanage sewage treatment works (STW) , discharges to the sea
170m east of Peverill 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 Swanage Central
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 10% of visits, with 76% of visits noting the presence of litter. Tarry residue
was not noted at this site.
The catchment surrounding Swanage Central is approximately 1,800 hectares and includes
the small and very steep catchment of the Swan Brook and Ulwell Stream.
The Swan Brook is approximately five and a half kilometres long (including tributaries)
and flows to the southeast across the Isle of Purbeck to Swanage. It splits into two
watercourses that are channelled underground through the town. One channel is piped
under the beach and enters the sea 160m south of the Environment Agency monitoring
point, and the other flows through the town and across the beach 460m to the south.
The Ulwell Stream is approximately two and a half kilometres long and flows from Nine
Barrow Down south to Swanage Bay 330m north of the Environment Agency monitoring point.
The catchment is mostly agricultural, with around 20 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.
