Colwell Bay is a small resort situated on the north west coast of the Isle of Wight
with panoramic views of the Solent and Hurst Castle. The sandy beach slopes gently.
The area has several café's and facilities close by.
This bathing water is affected by the Colwell Chine storm overflow and Monks Lane
storm overflow, at the north end of the bay. The overflows can discharge when heavy
rainfall overwhelms the sewerage system but they are designed not to affect bathing
water compliance.
Outfalls at Totland and Yarmouth were transferred to Norton in 1994 and on to Sandown
sewage treatment works by 2002.
Five storm overflow improvements in the Norton area were completed during 1997 and
1998.
The single standard failure in 1997 was due to a Combined Storm Overflow discharge
into the Colwell Chine which flows to the sea close to the sampling point.
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 78% of visits. The shore can become covered with seaweed, depending on
tides and the weather. Groynes, rocks and other fixed objects may have a covering
of seaweed which can be slippery.
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 not noted at this site. Microscopic algae (phytoplankton)
increase in number at certain times of the year. This process is known as a phytoplankton
bloom. Blooms of phytoplankton can result in the water appearing discoloured or a
foam forming on the water.
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 5 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.
The Colwell Chine enters the sea at this bathing water. Streams are typically affected
by human or industrial inputs from further up the catchment. Water quality at this
beach is consistently excellent. There is no evidence of any significant effects from
the stream on bathing water compliance.
Environment Agency samplers make observations of litter present on the beach at every
visit, this includes assessments of sewage debris, litter and tar. At Colwell Bay
for the four year (2020-2023) assessment period where data is available, sewage debris
was not assessed as being sufficient to be objectionable, but was observed as being
present on 2% of visits. Litter was not assessed as being sufficient to be objectionable,
but was observed as being present on 42% of visits. Tarry residue was not noted at
this site.
The natural drainage (hydrological) catchment surrounding the bathing water is about
120 hectares. The catchment includes a Holiday Village, farmland and much of Colwell
village.
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.