Nutrient pollution has become one of the most persistent environmental challenges. At the heart of the issue are two key culprits: phosphorus and nitrogen. When these nutrients enter watercourses in excess, they fuel the rapid growth of algae and other micro-organisms, degrading water quality and harming wildlife.
Natural England has been clear that reducing these nutrient levels is essential to protect vulnerable habitats. One of the main tools used to achieve this is the Habitats Regulations Assessment (HRA).
What Is the Habitats Regulations Assessment?
Nutrient neutrality sits within the wider HRA process, which forms a critical part of the planning system. Its purpose is to ensure that new development does not increase nutrient loads in watercourses that feed into protected habitats downstream.
Local Planning Authorities (LPAs) must consider whether a proposed development, either alone or in combination with others, could significantly affect designated sites that protect habitats, flora, fauna, and wild birds. If there is a risk of significant impact, the LPA must carry out a detailed assessment and identify solutions to avoid or mitigate harm.
Crucially, planning permission cannot be granted if adverse effects cannot be ruled out and no suitable mitigation is available.
Mitigation Measures: Necessary but Challenging
To achieve nutrient neutrality, developers are often required to implement mitigation measures. These can include:
- Creating semi-natural habitats
- Constructing wetlands
- Installing advanced drainage or water treatment systems
Any solution must be scientifically robust, fully funded, and secured for the lifetime of the development. It must also be preventative, not merely compensatory.
While these measures are environmentally beneficial, they are also highly technical, site-specific, and time-consuming to design and deliver.
The Impact on Development
It’s no surprise that nutrient neutrality has become a major bottleneck for development, particularly housing.
Because mitigation must be tailored to each site, and because suitable solutions can take years to plan and implement, many projects stall. This has raised concerns about the viability of development in affected catchments and the wider impact on housing supply.
Developers argue that they are being unfairly targeted. They point out that the majority of nutrient pollution comes from wastewater and agriculture, not new homes. Given that the additional nutrient load from housing is relatively small, many in the sector view the current rules as disproportionately burdensome.
Proposals for Change
Reform has been on the government’s agenda for several years. In 2023, amendments were proposed through the Levelling Up and Regeneration Bill, though these ultimately did not progress.
More recently, in December 2025, the Planning and Infrastructure Act 2025 introduced the Nature Restoration Fund (NRF). Under this model, developers working in protected catchments would be able to pay a nature restoration levy. The funds would be used by Natural England to deliver mitigation through Environmental Delivery Plans (EDPs).
In essence, the NRF aims to streamline the process by shifting responsibility for mitigation delivery from individual developers to a centralised, expert-led system.
Looking Ahead
Nutrient neutrality remains a vital environmental safeguard, but it is also a significant constraint on development. The challenge for policymakers is finding a balance between protecting sensitive habitats and enabling the delivery of much‑needed housing and infrastructure.