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First steps towards achieving phosphorous neutrality in Somerset
Achieving nutrient neutrality by reducing phosphorous and nitrogen loading on ecologically sensitive coastal and wetland habitats has become an ever growing source of frustration for housing developers across the country.
Several have seen their projects significantly delayed or even refused. In Somerset, decisions to approve over 11,000 homes have been halted because of the impact of phosphorous on the Somerset Levels & Moors designated sites. With a phosphorous budget calculator having recently been published by Somerset’s affected Local Planning Authorities, the first step has been taken in helping developments progress towards nutrient neutrality, but there is still a long way to go.
What is nutrient neutrality?
This issue stems from a ruling at the Court of Justice for the European Union back in November 2018, known as the Dutch N case [1]. This resulted in Natural England, the Government’s advisor on the natural environment, revising its interpretations of the Habitats Regulations. Certain nutrients, such as phosphorous and nitrogen, regularly flow through waterways and into the sea. In some places these nutrients have been accumulating to such levels as to result in increased growth of algae and other aquatic plants. This results in significant changes to the ecosystem and general degradation of water quality, a process known as eutrophication. In light of the Dutch N case, Natural England has advised a number of Local Planning Authorities that due to the unfavourable status of various protected sites as a result of eutrophication, there needs to be certainty in affected areas that new development will not add to the nutrient burden as a result of land use changes or wastewater discharges.
This advice resulted in many affected Local Planning Authorities issuing moratoria on new developments that could increase the nutrient burden, namely those that would generate additional overnight stays such as residential and tourist developments, or certain agricultural developments. Affected developments included those in the Solent region, east Kent and more recently, the focus of this article, Somerset.
What is happening in Somerset?
In August 2020, Natural England advised the four district authorities, Mendip, Sedgemoor, Somerset West & Taunton and South Somerset, as well as Somerset County Council and neighbouring Dorset Council, that high levels of phosphorous were degrading the Somerset Levels & Moors.
The Somerset Levels & Moors are designated as a Special Protection Area and are listed as a Ramsar site. Therefore, any development which could increase the phosphorous burden in the catchment area for these designated sites, as identified in the map below, would need to be subject to a Habitats Regulations Assessment. These developments, such as those for new homes, would need to demonstrate they were phosphorous neutral or that sufficient mitigation could be achieved to make them phosphorous neutral.
Consequently, the Somerset authorities had to delay decisions on 11,000 new homes whilst trying to work out the practicalities of achieving phosphorous neutrality.
An ongoing two-step process
Step 1: Complete a phosphorous budget calculator
To know if a development will be phosphorous neutral you first have to know how much phosphorous a development will generate, as well as the amount of phosphorous currently generated on site. To help developers with this, Somerset West and Taunton Council, using funding from Homes England, has led the joint commissioning of Royal HaskoningDHV to prepare a phosphorous budget calculator [2]. This calculator has been signed off by Natural England and has now been published online [3]. It is being deployed by all of Somerset’s Local Planning Authorities to help developers in their phosphorous budget calculations. Although developers beware, the calculator may be subject to regular updates as new guidance and scientific findings are published.
This calculator is a useful first step and will allow developers to gauge their phosphorous burden. In some cases this will help identify that a development would reduce or have a neutral effect on the phosphorous burden on the Somerset Levels & Moors, compared to the status quo. Such schemes can therefore progress to determination without the need to provide mitigation. In other cases it will help quantify the amount of additional phosphorous that would be generated which will inform how much mitigation needs to be provided.
Step 2: Securing mitigation – the greater challenge?
With the calculator informing how much phosphorous a development would generate, the challenge for those developments generating an increase in phosphorous will be how to mitigate this. Such is the scale of this challenge that the leaders of Somerset’s Local Planning Authorities submitted a joint letter [4] to the Secretaries of State for the Environment and for Housing, Communities & Local Government calling on them to help deliver a national solution. The response from the Minister of State for Housing [5] is somewhat underwhelming in providing a way forward, but does at least provide some hope in getting all the relevant parties to the table to work on a solution.
There is a general expectation from the Local Planning Authorities that the new calculator will help clarify whether some developments can provide on-site mitigation using suitable land management proposals. These could include areas of constructed wetlands, woodland, meadow or open space. Of course, the amount of land required to provide adequate mitigation may be undeliverable on some sites leading to a need to provide off-site mitigation.
There is also some hope for small scale proposals that intend to use septic tanks or package treatment plants. Recently published interim guidance [6] from the Somerset Ecology Service at Somerset County Council, in collaboration with Natural England, sets out thresholds where these means of disposing of foul water would be considered to cause an insignificant amount of phosphorous to discharge to the ground. If below these thresholds then the proposal would not have a likely significant effect and could pass a Habitats Regulations Assessment.
The Somerset Ecology Service are also currently working on a Somerset-wide nutrient strategy to identify both short-term solutions to help currently undetermined planning applications, and longer-term solutions to address existing and future development allocations and growth commitments. At a recent Q&A, the Local Planning Authorities announced their intention to publish this strategy, which will inform a draft Supplementary Planning Document, in autumn 2021. The mitigation identified in the strategy will likely require additional funding to be implemented and consequently the Local Planning Authorities are preparing a joint bid to the Natural Environment Investment Readiness Fund. This provides grants to groups such as local authorities for them to develop nature projects to a point where they can attract private investment, which in this case would likely be in the form of developer contributions.
Many wastewater treatment works in Somerset do not currently have permit limits for phosphorous. However, the local sewage undertaker, Wessex Water, is looking to undertake upgrades to ensure that many will operate under the new permit levels allowed under the asset management period for 2020-2025, known as AMP7. These upgrades will reduce the amount of phosphorous leaving the wastewater treatment works meaning that the phosphorous burden generated from a development’s foul water outputs will be reduced. However, all the upgrades may not be fully in place until 2025.
There is therefore a worrying commonality in the means to providing off-site mitigation and that is there is no quick fix. This is not something developers who have been stuck in limbo since August 2020 will wish to hear. It is also not necessarily a surprise to those already involved with proposals in the Solent region, where strategic mitigation proposals for achieving nitrogen neutrality have taken similarly long periods of time to get off the ground.
A waiting game?
With the arrival of the phosphorous budget calculator, developers now have the means to calculate their phosphorous burden and quantify how much mitigation they may need to provide, a welcome first step. However, for those who find they cannot provide this mitigation on-site there will likely be a significant amount of time before any off-site mitigation schemes come forward. Similarly, the upgrades at the wastewater treatment works that will reduce a development’s phosphorous burden are on the horizon but are still some way off. Overall, not a situation that will sit well with many developers who must continue to play the waiting game whilst viable mitigation solutions are developed.
Nutrient neutrality and how we can help
We provide regular updates on issues of nutrient neutrality and we remain well placed to advise our clients and guide affected developments through the planning process. We are aware that issues of nutrient neutrality are now affecting developments across many parts of the county, and we are able to apply our significant expertise on the issue to assist those with developments in affected areas.
If this is something we can help you with please do not hesitate to contact James Cording for an informal discussion.
25 March 2021