The water quality of the Solent area is being affected by excessive levels of nutrients being added to the water – specifically nitrates and phosphates. This comes from a number of sources, however there is concern that additional units of overnight accommodation (dwellings, hotels, tourism units etc) are adding to the problem.  In order for development schemes to be permitted, they need to be ‘nutrient neutral’ or provide sufficient mitigation.

Developers are therefore required to submit further information as part of their application. They must demonstrate how many nutrients are being added to the water system from their development and provide acceptable mitigation. The illustrative overview ^{(pdf, 1.4mb)} shows the issue and process developments need to follow. 

The Council’s Position Statement sets out how development proposals should consider nutrients and a number of mechanisms for development to achieve nutrient neutrality:

• WCC Nutrient Position Statement ^{(pdf, 110kb)}
• Nutrients Illustration ^{(pdf, 1.4mb)}

Details of available schemes (including which river basin catchment and waste water treatment works they serve) are all available via the link below.

Potential Nutrient Mitigation Schemes - Partnership for South Hampshire (push.gov.uk)

This section contains all the information you should need for your application. It is important that nutrient neutrality is considered as part of your submission, and it is a  Local Validation Requirement to submit the required documents.  Any proposed changes to a dwelling that will increase the number of over-night accommodation (i.e. splitting one home into separate flats) will need to meet the nutrient neutrality requirement to legally gain planning permission.

Natural England’s advice for achieving nutrient neutrality and calculating the nutrient budgets for planning applications in both the Solent and Itchen Catchment can be found here:

• Solent Nutrient Budget Calculator Solent January 2024
• River Itchen Nutrient Budget Calculator January 2024

The Natural England Summary Guide and Generic Methodology breaks down each stage of the calculator in detail and provides links to approved sources of  data needed to complete the calculator.

Information on Mitigation required to achieve Nutrient Neutrality

The Natural England Summary Guide and Frequently Asked Questions paper provides a table of potential mitigation options that could be used to generate mitigation. A nutrient avoidance and mitigation package will be needed to achieve nutrient neutral development before a planning permission can be lawfully issues in accordance with The Conservation of Habitats and Species Regulations 2017.

Natural England provide a  Discretionary Advice Service (DAS).

Further useful link

Tools and resources for calculating nutrient neutrality - GOV.UK (www.gov.uk).

To provide on-site nutrient mitigation, it is advised that the Local Planning Authority and Natural England through the Discretionary Advice Service are contacted at the earliest opportunity. The on-site mitigation will need to be managed and monitored in perpetuity (usually 100 years) to ensure targets for nutrient reduction are being met.

A nutrient budget should be included as part of the planning application information when it is submitted to the Council. The table below provides details on the mitigation schemes that can serve development in Winchester.

If your development site is within the Test and East Hampshire catchment, you will need to consider nitrate neutrality only. We will require the following documents:

• Nitrate Calculator
• European Sites Checklist

If your development site is within the Itchen catchment, you will need to consider nitrate AND phosphate neutrality. We will require the following documents:

• River Itchen Calculator
• European Sites Checklist
• Details of your proposed mitigation

Once you submit your application with the documents listed above, the case officer will assess this information alongside Natural England. The case officer will keep you updated with any issues or further information requests.

For mitigation sites, the Partnership for South Hampshire keep their dedicated webpage up to date with the latest available sites. This includes contact information to allow you to contact the provider to discuss further.

Nutrient Mitigation for New Housing Development - Partnership for South Hampshire (push.gov.uk)

You may also find the following information useful:

•  WCC Position Statement on Nitrates
• Natural England Methodology Guidance
• Natural England Discretionary Advice Service
• Potential Nutrient Mitigation Schemes - Partnership for South Hampshire (push.gov.uk)

In addition to the above information there are also a number of documents that have been published by other stakeholders to understand nutrient neutrality:

• Nutrient Update Statement March 2022 ^{(docx, 49kb)}
• European Sites Checklist ^{(docx, 65kb)}
• Cabinet Reports (July 2020, July 2021) ^{(pdf, 19.9mb)}
• Letter to Robert Jenrick ^{(pdf, 312kb)}
• Section 106 Draft Heads of Terms ^{(docx, 44kb)}
• Letter to Applicant and Agents ^{(pdf, 127kb)}
• Winchester Position Statement ^{(pdf, 110kb)}

Natural England:

• Nutrient Neutrality and Mitigation: A summary guide and frequently asked questions
• The Solent Catchment Map
• Nutrient Neutrality Calculators (Solent and Itchen) and Nutrient Neutrality Generic Methodology
• Joint Position statement - Natural England and Environment Agency 18 November 2019. ^{(pdf, 259kb)}
• Nutrient Neutrality Principles
• River Itchen Special Area of Conservation Evidence Pack
• Water Quality and Nutrient Neutrality Advise Issue 1 Final ^{(pdf, 499kb)}
•  Information on Nature Based Solutions as Nutrient Mitigation - NBS2024 (naturalengland.org.uk)

Partnership for South Hampshire (PfSH)

• PfSH Solent Mitigation Page and Scheme Map
• PfSH Webpages on Nutrient Neutrality Across the Solent

Wincheester Planning Office:  planning@winchester.gov.uk

Partnership for South Hampshire (PfSH): skennedy@fareham.gov.uk