2024 Bathing Water Profile for Porthminster
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Porthminster is on the north coast of Cornwall. It is a sandy beach resort, approximately 1.1 kilometres wide, with a gentle slope making it easily accessible.
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Cornwall
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Cornwall
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We will review the freshwater monitoring carried out in the 2023 Bathing Season to better understand pollution sources
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There is a storm overflow from the Wescots Quay CSO. The overflow discharges to Porthminster Beach 410m from our monitoring point. The overflow prevents local homes from being flooded with sewage after very heavy rainfall. The operation of the overflow 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/
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In the past Porthminster bathing water was affected by the untreated outfall at Bamaluz Point, although 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 2.7km long sea outfall west of Godrevy Head. The Hayle STW was enlarged and upgraded in 1995 and again in 2000.The combined sewer overflows (CSO) at Pedn Olva and Stennack Culvert were sealed in November 2001. Storm overflow event duration monitoring (EDM) was installed at the Wescots Quay pumping station by December 2011. Porthgwidden SPS_PSCSOEO, Porthminster SPS_PSEO, and Westcots Quay Tank all had Event Duration Monitoring installed and an annual spill return is completed by SWW at the end of each bathing season.
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The urban area of Porthminster immediately behind the beach is served by a combined (surface and sewer) system. There is a surface water outfall from Smeaton's Pier that discharges 620m north of the designated monitoring point.
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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 70% of visits. This bathing water does not have a history of large amounts of seaweed (macro algae).
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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.
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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 2% of visits. 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.
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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.
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2024 Bathing Water Profile for Porthminster
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2024-09-30
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2024-05-01
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Streams and rivers are typically affected by human sewage, animal slurry and runoff from roads. There are two streams entering the sea near this beach (marked by the green circles on the bathing water map) which can affect water quality during and after heavy rainfall.
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Sewage from the St Ives area is pumped to Hayle STW for treatment, and discharges to the sea five kilometres northeast of the bathing water. This discharge is designed to protect bathing water quality.
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Environment Agency samplers make observations of litter present on the beach at every visit, this includes assessments of sewage debris, litter and tar. At Porthminster 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 2% of visits, with 54% of visits noting the presence of litter. Tarry residue was not noted at this site.
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There are private and trade discharges within the catchment but we do not believe these are a source of pollution to the bathing water. If any concerns arise, we will investigate and request immediate remedial action from those responsible.
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The catchment surrounding Porthminster is approximately 650 hectares. A small stream 1.2km long enters the sea close to our monitoring point and is mostly channelled underground. The Stennack Stream is approximately three and a half kilometres (4.7km long including tributaries). It enters the sea to the south of St Ives harbour 400 metres (m) northeast of the Environment Agency's monitoring point. This is a fairly gently sloping coastal catchment with two or three high carns becoming steeper in St Ives and at the coast. Land use is mostly agricultural with just one or two farms. The catchment contains the majority of the resort town of St Ives, the rural area is mostly improved grassland.
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Porthminster
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Porthminster
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Sampling point at Porthminster
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152060
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50.20865951327619
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-5.476352469666611
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40080
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Sampling point at Porthminster
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p152 dT23 h59 m59 s
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2024 05 01 t00:00:00
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2024-05-01T00:00:00
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2024 09 30 t23:59:59
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2024-09-30T23:59:59
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2024 31000:1
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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.
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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.
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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.
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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.
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Discharges from sewage treatment works have improved substantially in England since the 1980s.
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