Ashford Borough Council's experience of nutrient neutrality

The council has had to hold granting planning permissions on a number of planning applications, for schemes which are caught by the issue. Around 90 per cent of site allocations in the Local Plan, and currently around 5,800 dwellings in over 170 planning applications, have been affected. This has significant implications on the housing land supply and housing distribution across the borough.

One of the significant impacts for Ashford is the impact of nutrient neutrality on the spatial strategy of housing in the borough and housing land supply (not just in the area caught by nutrient neutrality). Applications in the catchment which are otherwise considered sustainable now cannot progress through to a decision, which has materially reduced the council’s housing land supply.

Without strategic solutions in place, many of these schemes will continue to be held up, as mitigation cannot be accommodated on-site for a significant number of developments, due to constraints such as land size and location. This has had a consequential impact for the council’s land supply position, leaving the areas outside the catchment more susceptible to windfall development. These areas are often more rural in nature or covered by other environmental constraints, such as AONB. There is pressure that these areas should be required to ‘overcompensate’ and ‘pick up the slack’ for the sites which are caught by the current (albeit temporary) hold due to nutrient neutrality.

The impediment towards granting planning permissions has had further implications, aside from meeting housing targets. Many of these impacts are as a result of the inability to grant planning permissions and include reduced S106 monies, New Homes Bonus and infrastructure delivery, as the developments which would provide these benefits cannot currently progress through to a planning permission. There are also associated secondary economic impacts, including a hold on job creation and economic investment into the borough, which are also now affected as developments cannot currently progress.

Work undertaken by the council on nutrient neutrality, as part of its borough mitigation strategy, has shown that the most effective mitigation solutions within the Stour catchment, for both phosphorus and nitrogen, are strategic wetlands. For different catchment or areas which are only affected by one type of nutrient type, the mitigation approach may vary.

However, whilst wetlands are effective nutrient mitigation, constructed wetlands are an expensive solution. There are also a number of constraints associated with wetland delivery, including impact on water environment, river abstraction and the permitting process. Wetlands as a mitigation solution are not a ‘quick-fix’, any wetland creation will have a significant lead-in time for the planning/permitting process, construction, and growth and establishment of the wetland before it can function correctly and removing nutrients from the watercourse. Therefore, whilst this solution might have some benefits such as the lowest land-take for phosphorus, compared with other methods such as agricultural offsetting, there are still significant risks to such an approach.

In March 2022, when the Natural England methodology was updated, it was also announced that there was an intention to release guidance on how sustainable urban drainage (SUDs) can function as nutrient mitigation.  To date, this guidance has not been released by Natural England.  Until such time as this guidance is released, the council consider that wetlands are the most effective solution with Ashford borough. Based on the outcome of any future guidance, SUDs may provide an alternative effective solution, which is more feasible on the smaller development sites. In the absence of the SUDs guidance, the council considers that constructed wetlands, delivered on a strategic level, are the most effective use of land to deliver the nutrient mitigation required to release otherwise sustainable housing development in the borough.

The council is committed to its environmental duties, including preventing further deterioration of protected sites, such as the Stodmarsh Lakes. However, it is clear that a strategic response to nutrient neutrality is required to balance the competing issues of housing growth and environmental protections. The Council are committed to delivering a strategic mitigation solution and as stated above are proactively working on a borough mitigation strategy, which will aim to deliver nutrient mitigation within its own borough boundary. However, the challenges of delivering strategic mitigation should not be underestimated and the work that the council has done to date has shown that to deliver any strategic mitigation, input from the Government will be required, as well as organisations such as Natural England and the Environment Agency.

The largest challenge for nutrient neutrality is the current lack of national involvement towards strategically addressing the issue. Until the national ‘nutrient mitigation scheme’ announcement from Natural England, limited support has been received from government to address the issues nationally. Instead, the focus has been placed on individual Councils to deliver their own mitigation.

The council is aware that the issue affects each catchment differently, however there are still a number of issues that apply to all the Councils universally. This includes the impact on housing land supply and housing delivery test. Whilst the government previously set out that they would address the wider ramifications of nutrient neutrality on housing land supply through Planning Practice Guidance during Summer 2022 (Chief Planning Officer’s letter dated 21 July 2022), to date there has been no further update or any indication of when the update will be happening. The Council awaits further updates with anticipation and is hopeful that the government will provide clarity regarding these issues.

The council is supportive of the funding provided to each affected catchment to fund nutrient mitigation work, however this is considered a small sum of money, when compared to the projected costs of developing a catchment wide strategy, such as the delivery of strategic wetlands.

Whilst the council welcomes the news that Natural England intend to deliver a Nutrient Mitigation Scheme, Natural England need to provide greater clarity with regard to the timescales predicted to implement a suitable and effective solution.

Another challenge is the impact of the nutrient neutrality advice on areas outside of the catchment, and the implications that this has for sustainable development and growth. Within Ashford borough, around half of the borough’s land mass is covered by the catchment. The areas not caught by the nutrient neutrality requirement are inherently more unsustainable, rural in nature and often include sensitive environmental protections. 

Whilst the catchment only covers 50 per cent of the borough geographically, it covers around 90 per cent of the housing site allocations which were identified in the adopted Ashford Local Plan. This includes the urban area surrounding Ashford town, which is identified as the most sustainable location within the borough. Therefore, the most sustainable parts of the borough now have a significant constraint. The remaining areas, outside the catchment, which are more environmentally sensitive are therefore left ‘exposed’ to speculative development.

The council has seen a rise in the number of applications and appeals for larger schemes being promoted in areas outside the catchment.  Many of these refer to the challenges of nutrient neutrality as a means to justify the contribution of their site to help reduce the shortfall in housing supply.  The council’s view is that it should not be the requirement of the areas outside the catchment to ‘pick up the slack’ of housing delivery to over-provide, i.e. accommodate any shortfall, if it fundamentally conflicts with the borough’s recently adopted housing strategy (considered ‘sound’ through the Local Plan examination), and/or would result in harm by other means for example, to landscape character. To do so, would result in the unsustainable growth of these areas. It also decreases residents’ confidence in planning system and a plan-led approach, when planning applications have been granted at appeal in the areas outside the council, despite conflict with the Local Plan.

The council remain very much of the view that there needs to be government intervention at a national level to help address this issue, including by providing exceptions to the housing land supply and housing delivery test requirements for the affected LPAs.