Many forms of residential development, including new homes and other uses, which provide overnight accommodation, can potentially have an adverse impact on nationally protected sites in the district and broader Solent area because of the waste water they generate. The council, when making planning decisions, is required under relevant legislation to take this into account. Approval is only to be given if the council is satisfied that a development will not harm these nationally protected sites. 

One approach which has enabled the council to grant permission for housing schemes, and has allowed developers to keep building new homes, is to ensure ‘nutrient neutrality’. 

This is when the impact of development is off-set. This can involve developers buying “nutrient credits” from land owners who have changed the way their land is used and managed if this cannot be achieved on the development site itself. This means the level of nutrients reaching the environment does not result in an adverse effect overall that might otherwise be caused by the new development.

On the 16 March 2022 the council received new guidance from Natural England which will affect the way that the council has to assess new proposals across the whole district in terms of calculating the impact caused by the wastewater they produce. As this is the latest information available regarding nutrient pollution in Solent area we need to take it into account immediately.

In the case of the river catchment for the Itchen, which is a significant part of the district, the guidance advises that phosphorous and nitrogen are causing environmental effects. Previously only nitrogen was considered to need mitigation. 

This is a very significant change and will mean that the council will only be able to grant planning permission for new residential development, which potentially affects this catchment area, where the phosphate as well as the nitrate impact can be appropriately addressed. 

Unlike the position for nitrates, where a solution has already been established and has been working for some time which enables developers to mitigate the impact of their development by securing nitrate credits where the mitigation cannot be achieved on site, the situation regarding mitigation schemes available for phosphates is uncertain. It is not clear therefore how phosphate effects can be dealt with in cases where this is not achievable as part of the development being proposed. This means that unless it can be shown how a development proposal will avoid or mitigate any adverse effect on the nationally protected sites, the council will not at present be in a position to grant permission.

May 2023

Case officers continue to work with applicants on all other aspects of an application and, providing an extension of time is agreed, the application will be put on hold pending the submission of acceptable phosphate mitigation

Third-party mitigation schemes are starting to become available however they remain limited in number. There are also limitations to the amount of mitigation an individual site can provide.

Applicants are encouraged to approach mitigation providers and the council are happy to discuss mitigation on a case-by-case basis.

The Partnership for South Hampshire are maintaining their website with the latest updates which includes contact details for relevant schemes https://www.push.gov.uk/work/mitigation-schemes-available-to-developers/

March 2022

In light of the new guidance, which was issued without prior warning by Natural England, the council cannot progress planning decisions on certain types of planning applications for residential developments across the district until we consider and understand the implications for each case. We will be in contact shortly with applicants affected by these changes if we have not done so already. As explained above, the biggest implications will be for proposals which affect the Itchen catchment area.

Whilst this news may be a cause for concern for those involved in the development industry, who will want to avoid any delays in decision making affecting residential schemes, the council must meet its statutory obligations using the most up-to-date guidance provided by Natural England when determining applications. We remain committed to ensuring that the nationally protected sites in the district and broader Solent area are not adversely affected by the impacts of new development.

We will work closely with the Government, Natural England, neighbouring authorities and other interested parties to find solutions to tackle this matter, as we have done in the past, when nutrient pollution first became an issue in the Winchester district.

A position statement on nitrate neutral development was approved by Cabinet on 22 January 2020. The position statement sets out how development proposals should consider the issue.

The situation regarding nitrates is constantly evolving, with a number of mitigation schemes now being brought forward by private land owners, and this is reflected in an update on the council’s approach to the issue which was agreed by Cabinet on 21 July 2021.  Developers may be able to achieve nitrate neutrality for their developments by buying nitrate credits from these private landowners.  A table of potential schemes in each of the three river catchments across the district is provided in the list of attached documents along with the Cabinet report.  In most cases the mitigation scheme will need to be located in the same river catchment as the proposed development although this does not mean that the mitigation scheme has to be in Winchester district.

The council may also acquire nitrate credits itself,  or possibly in conjunction with other members of the Partnership for South Hampshire, which will then be offered to developers to purchase which is intended to meet the short term needs of smaller developers in certain parts of the district.  This option is not yet available.

The Solent has recognised problems from nitrate enrichment; high levels of nitrogen from human activity and agricultural sources in the catchment have caused excessive growth of green algae (a process called eutrophication) which is having a detrimental impact upon protected habitats and bird species.

As part of the information needed to determine relevant planning applications, a European Site avoidance and mitigation checklist will be required.

All applications and proposed mitigation will still be assessed by the council on a case-by-case basis in consultation with Natural England.

The council, together with other local authorities within the Solent catchment area, will continue to consider and investigate mitigation opportunities whilst discussions will also continue with government agencies and the wastewater industry on addressing the sources of nitrate pollution.