Southwest Environmental Limited

Nutrient Neutrality Assessment and Mitigation Strategy (NNAMS)

The requirement for an NNAMS is driven by Natural England's advice to specific Local Planning Authorities (LPAs). If your project falls within a sensitive river catchment or near a protected Ramsar site, you will likely be asked to provide this assessment. Key authorities currently requesting NNAMS or equivalent nutrient budget evidence include:

• Somerset Council: Covering the Somerset Levels and Moors catchment where phosphates are the primary concern.
• Herefordshire Council: Focusing on the River Wye Special Area of Conservation (SAC).
• Cornwall Council: Specifically for developments within the River Camel catchment.
• Norfolk Authorities: Including Breckland, Broadland, North Norfolk, and Norwich City Council for the River Wensum and the Broads.
• Hampshire and Solent LPAs: Such as Fareham, Portsmouth, Southampton, and the New Forest, where nitrogen neutrality is mandatory for the Solent.
• Kent Authorities: Including Ashford, Canterbury, and Maidstone for developments affecting the Stodmarsh national nature reserve.
• Tees Valley Authorities: Focusing on the River Tees catchment.

Southwest Environmental Limited have been working on the Parrett & Brue Phosphate Issue since its emergence late in 2020. We have dozens of reports lodged with Mendip District Council relating to Phosphates.

A Nutrient Neutrality Assessment and Mitigation Strategy will suggest one of two overall routes:

On-Site Mitigation

Typically this would be a treatment plant, filtrations system, and a constructed wetland. This is a good option if you have around 100m2 of spare space on your site (per house). However, these private drainage systems, can be contest on the back of the 30m rule.

Off-Site Mitigation

If you are building in a town, or a smaller plot with no room for mitigation on-site, you will need to create an off-site scheme. This is best achieved via tree planting, to create woodland. Constructed woodlands are take up less space than woodland, but are more costly to implement and the choice of suitable locations is few and far between. For a woodland scheme you will require approx. 0.5 hectares per dwelling.

Nutrient Neutrality Reports

If you need a Nutrient Neutrality Assessment and Mitigation Strategy (NNAMS) for you planning application please do contact us for a fixed price quotation. Email our Bristol Office, with plans and we will quote a price. Our turnaround time is approx. 5 to 10 working days. We are fast and flexible workers.

Somerset Council is mostly cover by Wessex Water: Location of Wessex Water Sewage Treatment Works

Nutrient Neutrality Assessment and Mitigation Strategy Contents

Typically contents:

• 1.0 Introduction    
• 2.0 The Site    
• 3.0 Background    
• 4.0 Scope    
• 5.0 Impact Assessment
• 5.1 Source
• 5.2 Pathway
• 5.3 Receptor     
• 6.0 Mitigation    
• 7.0 Private Drainage Justification    
• 8.0 Conclusions

In the appendixes of the report you will find:

• 1-  Conceptual Plans  (These are typically your plans with
• 2 - Phosphate Budget Calculator (For you specific area)
• 3 - Maintenance Details (How you will look after the system)
• 4 - PIA (Certificate to show how good the treatment plant is)

"Crafty" Short Cut

There are certain circumstances where you might not need an NNMAS, even though you have been asked to provide one. Reasoning:

An NNMAS is used to describe the changes on site, and derive a nutrient budget, it may also describe mitigation (such as tree planting).

After you have provided your NNMAS to Somerset Council (for example) they would use the NNMAS report to "inform" their SHRA. An SHRA repeats a lot of the information in an NNMAS, so in some circumstances you can skip the NNMAS and go straight to an SHRA. 

The SHRA only route really only applies if you intend to but nutrient credits. For site where you intend to mitigate on site, then you will need a NNMAS.

There is also the added bonus with this method that if you can submit the SHRA directly (avoiding the NNMAS) then it will also take work load off of the planning department and speed things up. It is not unusual to have to wait months for the council to do an SHRA for you.

The below section was written by a machine.

Technical Guidance: Nutrient Neutrality Assessment and Mitigation Strategy (NNAMS)

A Nutrient Neutrality Assessment and Mitigation Strategy (NNAMS) is a technical reporting framework required to satisfy the Conservation of Habitats and Species Regulations. In catchments where high levels of nitrogen or phosphorus are threatening protected water bodies, a formal NNAMS is often the only route to securing planning consent. This document provides the scientific evidence that a development will achieve a "neutral" impact on water quality through rigorous budget calculations and the implementation of robust nutrient mitigation options.

Nutrient Neutrality Beyond the UK

While "NNAMS" is a specific term commonly used in the UK planning system, the concept of nutrient neutrality is part of a broader international movement toward water quality management. The UK's current policy is a direct result of the European Court of Justice "Dutch Case" ruling, meaning similar assessment requirements exist across the European Union, particularly in the Netherlands and Germany, under the Habitats Directive. Outside of Europe, the United States utilizes "Nutrient Trading" and "Water Quality Offsetting" programs in sensitive watersheds like the Chesapeake Bay, where developers must offset phosphorus and nitrogen inputs to meet Total Maximum Daily Load (TMDL) standards. Similarly, parts of Australia and New Zealand have implemented discharge caps and offsetting strategies to protect the Great Barrier Reef and sensitive freshwater volcanic lakes.

The Role of NNAMS in Planning

An effective NNAMS must be integrated with the wider planning statement and design philosophy of the project. By calculating the pre-development and post-development nutrient loads, consultants can identify the "gap" that must be mitigated. This evidence is vital for the successful completion of a Habitats Regulations Assessment (HRA) and is often supported by Environmental Impact Assessments (EIA) to ensure that mitigation measures, such as constructed wetlands, do not adversely affect other site constraints. At SWEL, we provide the technical authority required to navigate these complex nutrient neutrality landscapes and secure project viability.