Research and analysis

Catchment statistics for nutrient pollution in protected areas 2026: executive summary

Updated 9 October 2026

Applies to England

The Environment Agency has provided summary outputs from their water quality modelling for protected area catchments where Diffuse Water Pollution Plans (DWPPs) are needed and where nutrient neutrality advice applies. We provide catchment-scale load source apportionment and comparison of diffuse sector concentrations with targets. Our outputs will help those working on DWPPs, designing or co-ordinating nutrient mitigation schemes, and working on site restoration. We aim to support a general understanding of the catchments rather than give the level of detail needed to inform specific on-the-ground measures. More detailed data and information, including maps, is available in the catchment specific modelling summaries alongside this report. This report and the associated catchment specific modelling summaries updates the data previously published in the Indicative Catchment Statistics for Nutrient Pollution report. (Version 1.2) published in September 2024.

Alongside Simcat SAGIS models, we used the Farmscoper v5 decision support tool and applied the revised polluter pays principle methodology (v0.17) used during PR24 planning to define the sector share for the point and diffuse sectors.

Our outputs highlight the dominant nutrient sources under a range of scenarios, including future estimates based on planned water company investment and the wider implementation of rural land use measures. When total input loads to all catchments are considered, we estimate the average rural land use phosphate contribution to be 53%, rising to 65% after the implementation of the current (2025 to 2030) Water Industry National Environment Programme (WINEP). We estimate that diffuse sector phosphate concentrations need to reduce by 51% on average.

By 2030, we estimate the rural land use contribution to increase above 80% in the Axe, Clun, Lugg and Tweed (England) catchments. In these catchments, we estimate that diffuse sector phosphate concentrations need to reduce by 60% on average, and up to 90% in the Clun catchment.

After the implementation of the current WINEP, we estimate the protected site targets to be met in the River Derwent (Yorkshire) SAC, River Ehen Special Area of Conservation (SAC), Esthwaite Water Ramsar and at the Sites of Special Scientific Interest (SSSIs) in the Waveney valley. In the River Derwent (Yorkshire) SAC and River Ehen SAC catchments we estimate the diffuse sector share of the phosphate protected area targets to be met throughout the designated reaches. In Esthwaite Water Ramsar, the total phosphorus diffuse share is estimated to be met if uptake of agricultural regulatory measures were to reach 100%.

We have not incorporated additional nutrient contributions from any future development and growth including housing. Any additional future nutrient load will be assessed through the planning process led by the Local Planning Authority or through the Environment Agency’s permitting process.

In almost all catchments, we estimate the reduction in nutrient losses achieved when applying catchment-wide rural land use measures to be insufficient to meet diffuse sector share. This is where additional or alternative measures would need to be explored to achieve the diffuse sector share of the target, for example through spatially targeted conversion of farmland to semi-natural habitat and woodland, habitat creation within and alongside farming, or innovation and technology to improve farm practices and manage flows of nutrients between sectors more efficiently.

For more information, read the full report.