Excessive nutrients (principally nitrogen) in the Solent’s European sites are causing eutrophication, leading to an increase in algae growth. This has an adverse impact on the habitats and species within the European nature conservation designations sites in and around the Solent to which the Habitat Regulations apply.
Following recent case law, Natural England has advised that there is a likely significant effect on the Solent’s designated sites due to the increase in wastewater from new housing and any other development providing overnight accommodation which would discharge into the Solent.
The internationally-designated habitats of the River Avon to the west of the New Forest are also affected by elevated levels of nutrients – in this case phosphates. The scale of planned new development in the catchment of the River Avon that falls within the National Park is low, but any proposals for net new dwellings and other forms of overnight accommodation in this catchment must demonstrate it is phosphate neutral.
Natural England recommends that the impact of development on water quality in the catchments of the Solent and the River Avon is examined within the Appropriate Assessment process. For this reason, we are requesting the submission of a Nutrient Mitigation Checklist for any planning application for a net increase in dwellings or providing overnight accommodation.
The Government has issued updated national guidance and tools for addressing nutrient neutrality. This includes revised nutrient budget calculators for both the River Avon and Solent catchments, which supersede the previous version of the calculators. Importantly, the revised budget calculators factor in the upgrades to certain wastewater treatment works required by 2030 under the provisions of the Levelling Up & Regeneration Act 2023.
This updated information and relevant budget calculators are available to download from the Government website here: Using the nutrient neutrality calculators – GOV.UK (www.gov.uk).
