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CaSTCo case study

Working together to understand river health

The Catchment Systems Thinking Cooperative, otherwise known as CaSTCo, puts people at the heart of river recovery. Led by United Utilities and the Rivers Trust, CaSTCo brings together the expertise and backing from more than 30 organisations nationwide, including community and local partnerships, water companies, environmental charities, regulators, technical experts, academics, and the private sector. Together, we’re demonstrating how citizen science and community monitoring methods can be used alongside professional monitoring to generate and share accessible data of known quality so that the information produced leads to better and more impactful decisions. It is a £7.1 million 3-year project funded by the Ofwat Innovation Fund, concluding in September 2025.  

The North West demonstrator focusses on the Mersey and Ribble catchments and aims to test approaches for collaborative working between Rivers Trusts, local CaBA partnerships, other eNGOs and partners, to share best practice methods for citizen science monitoring of rivers. It is exploring how collaboration could potentially reduce costs through sharing of resources, equipment, survey effort and knowledge. 

Collaborative monitoring on the River Bollin

United Utilities and Mersey Rivers Trust are working together, powered by CaSTCo, to develop capacity and capability for assessing the health of the River Bollin:

  • Mersey Rivers Trust have been able to train volunteer citizen scientists with methods and standards audited by CaSTCo, improving data quality and interoperability so that data is of known quality. To date more than 130 volunteers have been trained in water quality and vertebrate sampling.
  • We’re taking a new approach to understand and collate all of the data available for a more comprehensive view of what is being monitored and where, as well as any gaps.
  • Collaborative efforts are being coordinated on the ground through catchment wide sampling events and equipment sharing to enhance water quality monitoring and generate valuable insights.

Volunteers from Birkin Fly Fishers, Mottram St Andrews Fly Fishers, Mersey Rivers Trust and United Utilities’ River Rangers came together in October 2024 for focussed sampling across 34 sites, including 21 on the River Bollin, 6 sites on the River Dean catchment and 7 sites on Birkin/Mobberley/Sugar Brook catchment. Volunteers took site conductivity, pH and temperature readings and river water samples were analysed by Manchester University laboratory for multiple parameters including phosphorus, nitrate, other organic compounds and metals.

United Utilities also analysed results from up and downstream of Wastewater treatment works. Consistent monitoring at this location will help to show the efficacy of investment to upgrade the treatment facilities. Results from this survey were positive with phosphate levels within the range needed for improved water quality, and levels are expected to improve again once the upgraded works are fully commissioned. There was an increase of ammonia detected downstream of the wastewater treatment works but the levels are within the range for WFD High Status, the best category indicating no water pollution.

The results from the sampling event have been collated and shared by Mersey Rivers Trust and there is ambition that a North West hub will be developed where such results will be publicly accessible in the future, allowing informed decision making across the catchment.

Insights from the data are used to inform further action. For example, analysis from Liverpool John Moores University close to a former landfill site identified PFAS compounds and elevated conductivity. We will be working with Lindow Moss Partnership, Cheshire East Council, Manchester University and Liverpool John Moores University to conduct further sampling, investigate and plan action.  The sampling events are repeated twice a year to show trends over time and to identify any areas of concern for further investigation.

The information generated helps to inform stakeholders about the state of our water environment, as well as monitoring the benefits of interventions such as nature-based solutions, to make water more resilient to climate change, improve biodiversity, reduce reliance on chemicals and carbon lock-in, reduce carbon impact, and deliver wider societal benefits. Our work on Transforming the River Petteril is a good example of where catchment-wide monitoring surveying led to the implementation of wider catchment measures such as hedges, buffer strips of vegetation and sediment ponds and was a catalyst for the CaSTCo approach. 

Ribble ‘River Blitz’

Ribble Rivers Trust have been testing the ‘RiverBlitz’ approach to collecting environmental data, which is based on the more traditional ‘BioBlitz’, where volunteer groups come together in a fast-paced event to collect biological records of insects, plants and fungi. Bioblitzes however, only focus on terrestrial species, so RiverBlitzes are being trialled to ensure that our important riverine ecosystems are being monitored too.

The RiverBlitz method is a catchment-wide survey to assess river health. Surveying just one watercourse will give you an indication of its health, however, to understand where the potential health impacts come from, the tributaries that feed into it must also be surveyed.

Two RiverBlitzes were undertaken in 2023 on the Stock Beck and Duddel Brook catchments. Teams of passionate Citizen Science volunteers were assembled for a crash course in invertebrate sampling and identification before carrying out their surveys at strategic points throughout the sub-catchment. Water samples were also taken at the same time to test the phosphate levels and the condition of the habitat at each site was assessed.

CaSTCo’s innovative Community Water Lab was also used, enabling volunteers to test for E.coli, a process which usually relies on a lab for results and is particularly valuable in waterbodies with bathing water status. The results helped Ribble Rivers Trust to identify a site and a small tributary for investigation.

Without the help of the volunteer citizen scientists, collecting this type of data is expensive and time-consuming. Empowering local people to engage in water quality monitoring also has positive benefits for river health. Their honest and impartial feedback about the methods used in the RiverBlitz events will inform the development of a standardised approach to citizen science going forward. Their data, provided in a standard agreed format, also helps to paint a picture of water quality across a whole catchment which can feed into both strategies and decision making to identify where to target environmental improvements in the areas that need them most.