Water-Based Workstream

Water quality testing is a vital aspect of monitoring within the Erme catchment and provides one method by which we can assess the status of the river and its wider catchment. It is important to recognise the limitations and scope of the testing that is done, before relying too heavily on the results to provide conclusive proof as to how ‘healthy’ the Erme is.

What is the Environment Agency doing?
The River Erme has two sites officially designated as Bathing Water at Mothecombe and Coastguards. This status was awarded in May 1988 and May 2024 respectively and means they are tested weekly for E.coli and Enterococci by the Environment Agency over the bathing season; between the 15th of May and the 30th of September. 

2024 was the first full season of testing for Coastguards. When the Environment Agency (EA) announced the national Bathing Water results in November of that year, Coastguards was one of only two Bathing Waters in the whole of Devon to be given a ‘Poor’ water quality status. This meant the EA were then required to develop a plan to identify and investigate pollution sources and ensure the water quality is improved. To support this, they have been testing at Mothecombe, Coastguards, Holbeton, Ayleston, Sheepham and Sequers Bridge. Currently, this testing will only happen during the bathing season.

What is South West Water doing?
Because of the ‘Poor’ status of Coastguards, SWW are also required to work with the EA to develop a plan to significantly improve the current results. To do this SWW will have to conduct two days of sampling, throughout the tidal cycle, with the intention of building a better picture of how the tidal stage impacts water quality. They will also be testing water at Mothecombe, Coastguards, and upstream of Coastguards. The frequency of sampling and duration is not clear. 

What is WATER doing? 
WATER are keen to help feed into both the bathing water season sampling but also longer term monitoring. We have been awarded funds from Surfers Against Sewage to test water quality, at Coastguards, every week for one year (until May 2026). It is hoped this will develop a better understanding of water quality over the whole year. The EA’s ‘bathing season’ ignores the fact that many people use the water all year round for kayaking, paddle boarding and surfing as well as year-round swimming.

What are South Hams District Council Doing?
SHDC have a project running in collaboration with Valeport, a company that builds instrumentation for marine environments and the University of Plymouth. They are installing 6 sensors across the South Hams that will provide real-time continuous water quality readings. Test sites include the lower Erme.
 
How is water quality measured?
Both the EA and SWW undertake laboratory testing on water samples. This is done to measure the levels of E.coli and Enterococci in the water. 

The Environment Agency tests for E. coli and intestinal enterococci in bathing waters because these bacteria are internationally recognised indicators of faecal contamination. Here’s why they are used:

• Indicators of sewage or animal waste pollution
  Both E. coli and enterococci naturally live in the intestines of humans and warm-blooded animals. Their presence in water strongly suggests contamination from sewage, agricultural runoff, or other faecal sources.
• Health risk markers
  The bacteria don’t usually cause illness directly at the levels found in bathing waters, but high concentrations indicate a greater likelihood that harmful pathogens (viruses, bacteria, protozoa*) are also present. *Protozoa are microscopic creatures that live in water and soil, and sometimes inside other animals or humans. The pathogens link to risks of gastrointestinal illness, ear infections, skin rashes, and respiratory illness in bathers.
• International standards
  The EU Bathing Water Directive (2006/7/EC) and the UK’s Bathing Water Regulations require testing for these two organisms as the standard measure of microbiological quality. They are more reliable for reflecting health risks than older indicators, like total coliforms (bacteria). 
• Practical reasons
  They are relatively easy and cost-effective to culture and measure in labs, making them suitable for routine nationwide monitoring

How is WATER testing its samples?

While lab testing of water is the wider standard, it also requires samples to be posted and tested in a lab within 24hrs of the sample being collected. This can be problematic for volunteers and therefore WATER is using a technology called Bacterisk by Molendotech, a company developed by the University of Plymouth. 

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What is Bacterisk / Bactiquick

• The technology has been developed by Molendotech Ltd. (a University of Plymouth spin-out) as a rapid, portable test kit for assessing water quality. 
• It uses endotoxin detection technology to give a “bacterial risk” estimate. Endotoxins are molecules present in the cell walls of Gram-negative* bacteria. Their presence indicates possible contamination by such bacteria. *Gram-negative bacteria react to a Gram stain identifying technique, typically by turning pink or red.
• Broader detection: Because endotoxins are present in many Gram-negative bacteria, the test can potentially indicate the presence of bacteria beyond just E. coli / enterococci (including some that traditional indicator methods might miss) thus giving a more general warning about bacterial risk.

Limitations / things to be aware of

• Not a direct measure of specific pathogens: The test doesn’t identify which bacterial species are present. It measures a proxy (endotoxin) which indicates risk but not specific organisms. For example, it does not tell you whether E. coli, Salmonella, Vibrio, etc., are present.

How is SHDC testing its samples?

SHDC has been working with Teledyne Valeport, based in Totnes, to develop a monitoring approach based on a suite of high-quality continuous sensors that can monitor physical chemical and biological change within the water. 

Each individual sensor provides useful data; in combination, however, this is enhanced. 

• Temperature/conductivity (calculated salinity)
• Tryptophan (an amino acid), fDOM (fluorescent dissolved organic matter) and Turbidity (cloudiness) – these work best when measured together, as the addition of fDOM and Turbidity reduces the likelihood of false positives in the Trytophan measurement.We hope in future to make our results available via our website/social media and will of course provide dates at our annual public meeting.