Nutrient Neutrality

Olivia Maxwell: July 2023

What is Nutrient Neutrality?

Nutrient Assessments refer to a future developments NET Nutrient load on the surrounding environment. For a development to be Nutrient Neutral, it will not have a nutrient load that is greater than the nutrient load prior to the development.

The nutrients referred to are Nitrogen, Phosphorus or both.

In June 2019, guidance was issued to Planning Authorities in the Solent Region by Natural England giving advice on how to achieve nitrate neutrality in The Solent Region (Advice on Achieving Nutrient Neutrality for New Development in the Solent Region, Natural England, June 2019), which has subsequently been updated in March 2022 to cover multiple areas of the country (Advice for development proposals with the potential to affect water quality resulting in adverse nutrient impacts on habitats sites, Natural England, March 2022).

This guidance followed two rulings in the European Court of Justice which deemed that regulatory authorities in the Netherlands had not undertaken sufficient checks to ensure that proposed developments would not cause a significant harm to European Natura 2000 sites.

Natura 2000 classifications include SSSI, SAC, SPA & Ramsar sites.

Whilst the majority of nitrates entering water bodies are derived from current and historical agricultural sources, new developments have been deemed to result in an increased load on existing Wastewater Treatment Works (WwTWs) resulting in increased nitrates being discharged into the watercourses.

The new guidance by Natural England has resulted in certain local authorities requiring nitrate neutrality calculations and reports to be produced for all new developments.

Why is Nutrient Neutrality important?

An increase in the concentration of Nitrogen and Phosphorous in surrounding water bodies can cause eutrophication. A eutrophic water body will be high in nutrients, turbid and green from dense phytoplankton growth.

Due to this dense algae growth, the light penetrating into the water column will be low, and there will be a low species diversity, and low oxygen, making it difficult for aquatic insects or fish to survive, in turn removing a food source from the food chain.

Where is Nutrient Neutrality an issue and Who is affected?

Natural England (https://publications.naturalengland.org.uk/publication/4792131352002560) have highlighted areas of the country where development proposals could have an adverse impact on designated habitats, and nutrient neutrality has been identified as a potential mitigation solution.

Nutrient Neutrality is a national concern with approximately 74 Local Authorities falling within areas of concern.

Affected areas include:

  1. The Solent
  2. Cheshire East,
  3. Lake District National Park;
  4. River Avon SAC;
  5. River Camel SAC;
  6. Broadland and South Norfolk;
  7. Peak District National Park,
  8. Folkestone and Hythe;
  9. Carlisle;
  10. Stodmarsh SAC/Ramsar;
  11. River Wye SAC;
  12. Stockton-on-Tees;
  13. Somerset Levels and Moors Ramsar

All developments that propose overnight accommodation are affected by this guidance, including new housing developments, hotels and camping sites.

Each council within an affected area has released its own guidance on how to move forward with Nutrient Neutrality, and many have produced their own calculators.

How are Nutrient Neutrality assessments completed?

The nutrient balance of a development needs to be considered early, as mitigation measures may need to be designed on-site, or off-site mitigation measures may need to be arranged, which can cause delays to the proposed development planning approval.

Omnia can help you to produce Nutrient Neutrality assessments. In order to complete a nutrient neutrality assessment we will assess the nutrient load of the current site based on its uses, and compare it with the nutrient load of the proposed development.

The sites future nutrient load will be dependent on the proposed development, the future population of the site, the water usage of the development and any mitigating factors, such as proposed wetlands.

What happens next?

Following completion of a nutrient neutrality assessment, it may be determined that your proposed site will have a higher nutrient load than the existing site, and therefore mitigation measures may be required.

Mitigation can be on-site, through the construction of wetlands, land use changes, or implementing SUDs  for example, or off-site by off setting the nutrient load against another parcel of land, in agreement with another site, or through purchasing credits. A lot of mitigation options are available and early consultation with the Local Planning Authority and Natural England is advised.

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Speak to an Expert

Olivia Maxwell

Principal Geo-Environmental Consultant