We have been working with the landowner, the Rivers Trust, Bristol Avon Rivers Trust and the Environment Agency to discuss river water quality at the location, which can be affected by a number of factors – from our storm overflows and treated wastewater from our water recycling centres being returned to the river upstream to agricultural run-off, septic tanks, road drains and wild animals.
In September 2020 intensive water quality monitoring took place, involving a partnership with The Rivers Trust with Bristol Avon Rivers Trust, Wessex Water, Sewage Free Swimmers and the Environment Agency, and a team of volunteers.
To understand more about water quality at this location, investigative work is underway to find out more about the factors in the large river catchment upstream of the site which influence the condition of the river water and the role our assets have. This work involves collecting water quality information and river flow and weather data from Warleigh Weir and the catchment upstream, as well as trialling real-time water quality monitoring sensors in the river.
Real-time bacteria monitoring trial
The quality of bathing waters is measured by looking at the concentration of faecal indicator bacteria present in them. There is currently no technology that can continuously measure the concentration of these bacteria in rivers, which means we can’t provide people with this information in real time. Instead, samples have to be collected by hand and taken to a laboratory where the bacteria are analysed under controlled conditions, which takes around three days.
However, there are many readily available sensors that can provide robust real-time measurements of other water quality indicators, including temperature, pH, conductivity, dissolved oxygen and river flow. We are working with UnifAI, a company specialising in the use of artificial intelligence (AI) technology, to trial an approach that uses algorithms to develop relationships between these readily measurable parameters and the concentration of bacteria in water.
The trial, which will take place between 2021 and 2023, will involve installing a series of sensors, collecting water samples and analysing bacteria in the laboratory. As more data is collected, the AI will develop these relationships, which will hopefully allow us to stop analysing samples in the laboratory and start providing the public with real-time water quality notifications.
Storm overflows act as relief valves, allowing excess stormwater to be released to rivers or the sea. This protects properties from flooding and prevents sewage backing up into streets and homes during heavy storm events.
We monitor when storm overflows are in use that affect bathing waters and information is provided on Coast and rivers watch. This now includes information on when our storm overflows operate which affect some inland waters, including Warleigh Weir. You can find out the location of storm overflows and how often they are in use on our online mapping system.
We have extended our notification system which now includes when the following sites are in use, which are upstream from Warleigh Weir:
- Culver Street, Bradford on Avon
- Monkton Combe, Mill Lane
- Freshford Water Recycling Centre (formerly known as sewage treatment works)
This information is sent to the landowner and anyone can use either our Coast and rivers watch system or the Surfers Against Sewage SaferSeas (and Rivers) app to find out when they have operated. The SaferSeas app also allows you to register for live information on these overflows.