Hampshire Avon Diffuse Water Pollution Plan: What you need to know

05 October 2026 5 minute read
A river flowing through a field

The EA (Environment Agency) and NE (Natural England) have published the Hampshire Avon DWPP (Diffuse Water Pollution Plan), setting out proposals aimed at reducing phosphorus (P) and nitrate (N) losses across the Hampshire Avon catchment. 

The plan has been developed in response to concerns that water quality targets are not being met and following legal requirements placed on the regulators to reassess whether existing measures are sufficient to address diffuse pollution affecting the river.

The NFU is actively engaged in discussions with the EA, NE and local farmer representatives to ensure that farmers' views are represented and that any future approach is practical, proportionate and evidence-based.

Why is this happening?

The Hampshire Avon is one of the UK's most important chalk river systems, supporting internationally important habitats and species, while also providing drinking water supplies. However, phosphorus and nitrate levels remain too high in parts of the catchment, contributing to water quality failures and environmental impacts across key tributaries including the Upper Avon, Wylye, Nadder and Lower Avon.

The catchment has already benefited from significant voluntary action, including Catchment Sensitive Farming, Countryside Stewardship and farmer-led initiatives. While these efforts have delivered improvements, the EA considers that further reductions in nutrient losses are required if environmental objectives are to be achieved.

It is important to note that agriculture is not the only source of nutrients entering the river. Water companies, urban sources and naturally occurring background phosphorus also contribute to nutrient levels within the catchment.

The NFU continues to emphasise that improving water quality must involve action from all contributing sectors.

What is the Diffuse Water Pollution Plan?

The DWPP is a catchment-wide plan that establishes nutrient reduction targets and proposes a framework for measuring and reducing nutrient losses from farming businesses. It introduces catchment and farm scale phosphorus and nitrate emission limits and proposes the use of new nutrient assessment tools to help farmers understand and manage nutrient losses. 

The plan proposes:

  • A catchment wide phosphorus emission limit equivalent to 0.167kg phosphorus per hectare per year to be met by 2033.
  • Nitrate emission limits within designated Safeguard Zones. Check for Drinking Water Safeguard Zones and NVZs
  • The use of a new Phosphate Loss Tool (PLT) and, where applicable, a Nitrate Leaching Tool (NLT) to estimate nutrient losses.
  • Annual assessment of compliance through the Agricultural Compliance Tool (ACT).
  • A phased implementation period, often referred to as a "glide path", allowing farmers time to adapt. 

Many details around timescales and implementation remain under discussion and the NFU is continuing to engage with regulators on these issues. Currently the proposed timeline is to commence winter 2026.

Is participation mandatory?

One of the most important points for farmers to understand is that the DWPP itself is not a new regulation.

The EA and NE have confirmed that: “There are no additional statutory powers arising from a diffuse water pollution plan nor safeguard zone designation. A farmer’s adherence to our recommendations would be voluntary.”  

Participation in the DWPP and any associated farmer-led scheme therefore remains voluntary. However, farmers should be aware that existing legal requirements already apply through legislation such as:

  • The Farming Rules for Water.
  • The Reduction and Prevention of Agricultural Diffuse Pollution Regulations.
  • The Environmental Permitting Regulations 2016. 

The EA’s position is that where there is a significant risk of diffuse pollution, failure to follow advice or take reasonable steps may form part of the evidence considered during enforcement activity under existing regulations. 

What is the farmer-led scheme?

Alongside direct reporting to the EA, discussions are underway around the development of an EA-approved, farmer-owned and farmer-led scheme, similar to the voluntary Poole Harbour Nutrient Management Scheme. 

The intention is that such a scheme could:

  • Coordinate nutrient calculations and reporting.
  • Provide advice and support to members.
  • Allow data to be aggregated and reported anonymously through an independent organisation.
  • Reduce administrative burdens.
  • Demonstrate collective progress across the catchment. 

The plan is to have a single catchment-wide scheme which would be subscription based. Funding opportunities are continuously being explored. However, there would be farmer led company which would have a lead facilitator to run this group. These details are still being figured out, we are hoping to have more details about how to join this group as soon as possible.

What does ‘low risk’ mean?

A key aspect of the EA’s proposal is the use of nutrient reporting and compliance information to help identify businesses that are considered to be at lower risk of causing diffuse pollution.
The EA has indicated that farmers who submit the relevant information, either directly or through an approved scheme, may be considered lower diffuse pollution risk because they are able to demonstrate engagement with nutrient management and compliance processes. Conversely, where information is not available, the EA may find it more difficult to determine that a holding presents a low pollution risk.  
This does not mean that participation is mandatory, nor does it create new powers for regulators. However, it is one of the reasons why many farmers may wish to understand the scheme and consider how they wish to engage. 

The NFU’s position

The NFU believes:

  • Farmers are part of the solution and have already delivered significant environmental improvements.
  • Water quality improvements must be achieved through a fair and evidence-based approach.
  • Responsibility for improving the Hampshire Avon should be shared across all contributing sectors.
  • Farmers need certainty around legal requirements, reporting expectations and timescales.
  • Any farmer-led scheme must be transparent, practical and farmer-led in both governance and delivery.
  • Support, advice and workable transition periods will be critical to successful implementation.

What should farmers do now?

At this stage, the NFU encourages farmers to:

  • Read the DWPP information carefully.
  • Attend engagement events where possible.
  • Familiarise themselves with the proposed PLT, NLT and ACT processes.
  • Consider how current nutrient management practices align with the proposed approach.
  • Share questions and concerns with the NFU or relevant bodies.
  • Engage constructively in discussions about how a potential farmer-led scheme could operate.

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