Teifi demonstrator project evidence review

Executive summary

This evidence review is intended to support the progress of the Teifi Demonstrator Project (TDP). The TDP is a multi-organisational, cross-sector partnership aiming to deliver improvements to water quality and the wider water environment in the Teifi catchment, through collaboration and agile working. Successes will be captured and scaled up to use in other river catchments in Wales.

The Teifi catchment has a diverse landscape including both upland and lowland areas. It is mainly rural, and a large proportion of the population is employed in farming, which is also the predominant land-use. There is some flood risk in the catchment. A small amount of forestry is present in the upland areas and there is some broadleaved woodland mainly in the lower catchment, bordering the river and its tributaries.

There are numerous activities which impact water quality in the Teifi catchment including: water discharges, water abstraction, agricultural pollution, and materials to land application. Natural Resources Wales (NRW) regulates these activities to varying extents within the Teifi catchment. There are also statutory mechanisms in place to protect and enhance the water environment of the Teifi catchment, namely the Water Framework Directive (WFD) Regulations 2017 and the Conservation of Habitat and Species Regulations 2017.

The Teifi Catchment contains 37 river WFD water bodies, four WFD lake water bodies, one WFD transitional water body, the Teifi Estuary, and one WFD groundwater body. The change seen between the 2021 WFD Regulations full classification and a 2024 WFD Regulations interim classification presents a mixed picture for the Teifi catchment. The number of water bodies achieving overall Good ecological status increased from 37% to 44% and the number achieving Moderate ecological status decreased, however the number achieving Poor ecological status also increased from 14% to 16%.

18 river water bodies are designated as a Special Area of Conservation (SAC). SAC features assessments and water quality assessments are carried out. Atlantic salmon, sea lamprey, European otter, and river water-crowfoot are failing the 2020 indicative condition assessment. For water quality, the most recent assessment shows an improvement for three water quality parameters including Phosphorus. One water quality parameter, Trophic Diatom Index (TDI), has declined.

There are 12 water quality parameters assessed for SAC and WFD in 2021 and 2024 which have caused water body failures. The water quality issues vary along the length of the Teifi catchment.

Toxic metal pollution is the biggest issue in the upper catchment, whilst phosphorus pollution is mainly an issue in the middle and lower catchment. Phosphorus failures improved from 2021 to 2024. Hydrological regime is causing an issue in one of the lakes in the upper catchment, but the flow regime of the main river is mainly natural. Dissolved inorganic nitrogen (DIN) is an issue in the Teifi Estuary, which is also subject to short term pollution from faecal material during high rainfall events. The chemical Cypermethrin has caused an issue in one upper catchment water body in 2021, and one lower catchment water body in 2024. Sediment is expected to be an issue in the catchment although evidence is currently limited. Invasive Non Native Species (INNS) are an issue across the catchment although their exact distribution and impact is unknown.

The condition of invertebrates is an issue in the lake water bodies in the upper catchment and is largely unknown within the river water bodies. The condition of macrophytes and diatoms are an issue in the middle and lower catchment. Fish are the principal parameter which impact WFD water body ecological status across the catchment, and although the number of water bodies failing for fish decreases from 2021 to 2024, the severity of the failure increases in two water bodies. Biochemical Oxygen Demand (BOD) has previously been an issue in the lower catchment, this has improved in 2024 with no BOD failures in the catchment. There has been a minor improvement in Dissolved Oxygen (DO).

Phosphorus source apportionment modelling (SAGIS) and NRW’s Reasons for Not Achieving Good (RNAG) investigations show that pollution from waste water and rural land use are the greatest causes of water quality failure across the Teifi catchment. The impacts differ per water body and depending on the investigation approach.

There are many actions already being undertaken by stakeholders within the catchment to improve water quality and the water environment. Aside from the statutory duties of NRW and Dŵr Cymru Welsh Water (DCWW), these activities include: INNS removal and river re-meandering carried out by the Four Rivers for LIFE project; plans to reduce metal pollution through metal mine remediation projects; river walk-over surveys to identify barriers to fish migration; a Nutrient Management Plan (NMP) and numerous community engagement activities.

Intervention approaches for the TDP to take forward, to support the ongoing activities detailed above, include:

• A catchment management approach which applies river restoration and natural flood management techniques.
• Approaches aimed at adapting land management.
• Consideration of flexible regulatory approaches where benefits can be identified
• A collaborative approach reconnecting people with nature to achieve both cultural and environmental restoration. 
• Models and maps are available to help target certain interventions, alongside the evidence and information sources provided in this report.

The recommendations in this report are intended to inform future project development and delivery via the partnership. The delivery of these recommendations will be dependent on securing adequate project funding and collaborative effort. In summary, it is recommended to:

• Consider water quality assessment uncertainty and time lag.
• Look to fill evidence gaps such as knowledge of private sewage systems and the effects of sediment.
• Use a combination of approaches to improving the water environment that will strengthen cultural connections and collaboration whilst considering designated areas, intervention scalability, habitat networks and the targeting of specific water bodies outlined in the report.
• Focus on increasing granular detail in the existing evidence base and existing models, instead of creating additional catchment scale modelling.