Mill Bay is on the West bank of the Kingsbridge Estuary on the south coast of Devon.
It is a privately owned rural sandy bay, approximately 400 metres wide, surrounded
by hills. A stream flows along the south side of the beach to the sea.
There is an emergency/storm overflow from the Ager Point pumping station that discharges
to the Salcombe Estuary 250m north of Mill Bay. The operation of the overflow can
lead to a temporary drop in bathing water quality.
The South West Water sewage treatment scheme for Salcombe, which provides secondary
treatment and ultraviolet (UV) disinfection, was completed in 1996. The scheme included
some resewerage and improvement to combined sewer overflows (CSO).
The South West Water sewage treatment scheme for East Portlemouth, which provides
secondary treatment at Ditch End sewage treatment works (STW), was completed in April
1999. Repairs to the outfall at Ditch End were completed in summer 2000. Flows from
Mill Bay are pumped to Ditch End STW for treatment, and the outfall at Mill Bay has
been retained as surface water outfall. Gerston STW was improved by April 2003.
The following discharges into the Salcombe Kingsbridge Estuary have also been improved
to protect shellfish waters: West Charleton STW and CSO (October 2004), Frogmore and
Chillington STW (November 2005), Chillington SSO (April 2004), Sherford STW and SO
(March 2018) and CSO's at Bridge Street, Marlborough, Prince of Wales Road, Tacket
Wood SPS (July 2005), West Alvington (October 2005) and Chillington ( March 2018).
Storm overflow event duration monitoring (EDM) was installed at the Shadycombe Tank
and Comminutor House by December 2011, and EDM at Batson Green pumping station by
April 2016.
Improvements to Salcombe Malborough STW EO are scheduled for completion by March 2025.
South West Water are currently improving the sewer network higher in the catchment
and are also investigating and carrying out remedial works where saline water may
enter the sewer system.
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 84% 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 assessed as being sufficient to be objectionable, but
was observed as being present on 3% of visits. 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.
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 Hickham Stream flows across the beach to the south of the Environment Agency monitoring
point. The Environment Agency have monitored the stream between 1990 and 2008.
Sewage from a small number of properties on the northern side of Mill Bay is pumped
to East Portlemouth STW. The East Portlemouth STW outfall discharges to the Salcombe
Estuary one kilometre north east 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 Mill Bay 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 55% of visits. Tarry residue was not noted at
this site.
The catchment surrounding Mill Bay is approximately 8,800 hectares. The Hickham Mill
Stream is approximately 1.2 kilometres long and flows from the Hamlet of Rickham,
through fields and woodland to the estuary at Mill Bay beach, which is within the
Salcombe Kingsbridge Estuary. The estuary is unusual because it has no large river
feeding it, just a series of small streams rising from springs at Frogmore, Bowcombe,
Batson, East Allington, Sherford and other surrounding villages.
The estuary is tidal to Kingsbridge, 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 with secluded creeks and side arms. Woodland fringes come down to
the high tide line, and the areas of saltmarsh or grazing marsh are quite restricted.
Kingsbridge and Salcombe are the main urban areas and land use is rural.
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.