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Nutrient neutrality: Stodmarsh strategic mitigation solution

A case study on the challenges in delivering strategic nutrient neutrality schemes.

In September 2022 we provided an update on the latest nutrient neutrality position. As part of this update we mentioned progress that has been made in the Stodmarsh SPA/SAC/Ramsar catchment area and that Dover District Council are no longer impacted by the issue due to the findings of a connectivity study undertaken by the council, and subsequently accepted by Natural England.

While this is good news, the nutrient neutrality issue remains for other areas within the catchment, and consequently other relevant Local Planning Authorities are still required to develop mitigation solutions.

One such Local Planning Authority is Ashford Borough Council (ABC). Since July 2020, affected applications, including overnight accommodation in the borough, have been caught by the requirement to demonstrate nutrient neutrality to mitigate impacts on the Stodmarsh SPA/SAC/Ramsar sites.

This is particularly relevant as ABC’s update document highlights that some 85% of the council’s residential allocations are impacted by nutrient neutrality, with the more ‘sustainable’ areas of the borough being most affected. While a specific number of allocated sites which are impacted has not be published, we note that the adopted local plan has identified 5,889 dwellings as part of allocations (not including the allocation at Chilmington Green for 2,500 dwellings).

The council have been seeking to establish a strategic wetlands solution to generate mitigation credits to off-set the impact of new overnight accommodation, including residential development. This will likely involve the purchase of suitable land for mitigation in order to create the wetlands scheme.

To facilitate this, ABC are seeking to adopt a Supplementary Planning Document (SPD) that will provide details of the mitigation solution, clarify what details should be submitted alongside relevant planning applications, the details of the council’s mitigation hierarchy, advice on different types of mitigation and the details of the council’s strategic mitigation solution and how to ‘apply’ to the scheme for mitigation.

In October 2022, ABC provided an update on the progress of this mitigation solution. In short, the council have confirmed:

• The scheme will be delivered through a strategic wetland which is likely to come forward in phases, with phase 1 and phase 2 being the subject of a detailed planning application (with submission expected in early 2023 and determination in summer 2023). Currently it is estimated this might provide enough strategic mitigation to release around 5,000 dwellings. Planning applications for phases 3 and 4 of the strategic wetland are expected to follow in 2024.
• Progress on finalising the related SPD setting out this approach is dependent on the conclusion of an agreement with the landowner of the wetlands site, but ABC officers are continuing to draft the sections of the SPD that they can. A draft SPD is expected to be published for consultation in early 2023 to demonstrate the progress made to date (however an anticipated date for adoption has not been set due to landowner agreements).

The progress demonstrated by ABC is welcomed, however this brings up a much wider issue in relation to nutrient neutrality: the timescales involved in coming up with a strategic mitigation strategy. Getting to this point has required ABC and related technical advisers to dedicate a large amount of time and resources, to date it has been around 2.5 years since Natural England first identified the nutrient issue and the requirement for mitigation.

It demonstrates how much of a challenge it is to address a strategic solution to nutrient neutrality, involving: the identification of suitable land; securing landowner agreements; providing relevant technical supporting information to establishment agreement with Natural England; and developing a related policy framework.

Once ABC’s solution is implemented this will clearly be very helpful in the ability to grant permissions that are otherwise being delayed. The supply of 5,000 dwellings’ worth of credit will be finite and demand will be high given the significant backlog of applications that have stalled (while the scale of this backlog is not known, we do note that ABC have a Housing Land Supply requirement of 1,439 homes per annum). The council’s update references that the Stodmarsh SPD will include a ‘mitigation hierarchy’ which would presumably be designed to manage the distribution of credits and manage supply. While the detail of this has not been published, this could involve a system where specific allocations or smaller sites where mitigation cannot be provided on site are given priority in the distribution of credits.

However, this will not be the end of the issue. There will be pressure to secure future credits identified as part of phases 3 and 4 and ABC would need to minimise further delays where possible. Other Local Planning Authorities who have brought forward strategic mitigation solutions have experienced similar issues, particularly where the initial supply of credits has been bought up relatively quickly to address a backlog of stalled applications, and future supply of credits has been delayed due to other matters outside of the council’s control.

This will be a challenge for any mitigation provider. In our previous update we mentioned a range of new measures that were announced by the Government, including creating their own strategic mitigation scheme to be run by Natural England. While this would assist in providing more options for mitigation, the timescales associated with implementing a strategic mitigation scheme would equally likely apply to this scheme too. A key issue will be how the Government manage the setting up of new mitigation schemes in identified areas, to ensure that development can come forward in a timely manner.

To learn more about nutrient neutrality, including how it could affect your development please contact Jamie Hanna or Simon Packer.

10 February 2023