Policy ENV4: Nutrient Neutrality

Open22 Jan, 2024, 10:00am - 4 Mar, 2024, 11:59pm

Policy ENV4:  Nutrient Neutrality

New dwellings and development resulting in a net increase in population (including student accommodation, and tourist attractions and accommodation) served by a wastewater system that will discharge into the River Test and Itchen catchment (as shown on the Policies Map) will be required to demonstrate nutrient neutrality through the submission of a nutrient budget(s) in order to ensure that there is no adverse impact on the integrity of the following International nature conservation sites:

  • Solent and Southampton Water Special Protection Area
  • Solent and Southampton Water Ramsar site
  • Solent Maritime Special Area of Conservation
  • Solent and Dorset Coast Special Protection Area
  • Solent and Isle of Wight Lagoons Special Protection Area
  • River Itchen Special Area of Conservation

Development will only be permitted where the Council is satisfied that any necessary mitigation, management and monitoring measures are secured in perpetuity as part of the proposal and will be implemented in a timely manner to ensure that there will be no significant effect on the protected sites.

7.20 Wastewater effluent that discharges into the River Test and Itchen catchment could cause nutrient enrichment and is likely to lead to significant effects on the internationally designated sites for nature conservation in the Solent and the River Itchen SAC, either individually or cumulatively with other wastewater treatment works. For development that affects the Solent sites (the River Test and Itchen catchment), nitrogen neutrality will need to be demonstrated. Developments whose wastewater discharges to the River Itchen catchment will also need to demonstrate phosphorus neutrality. All new development that would result in a net gain in overnight accommodation is likely to result in a significant effect on the designated sites and will be subject to Habitats Regulations Assessment. There may also be some commercial or industrial projects which would cause an increase in nitrogen and phosphorus discharges and would be subject to a case-by-case approach.
7.21 Natural England have produced advice on achieving nutrient neutrality for new development in the Solent Region. This includes a nutrient budget calculator and accompanying mitigation guidance. A nutrient budget(s) will need to be submitted with an application, in accordance with the latest Natural England guidance, to determine whether the development is nutrient(s) neutral. If there is a nutrient surplus, appropriate mitigation will need to be demonstrated through on-site or off-site measures to ensure that any nutrient surplus is mitigated, otherwise development proposals will be refused. The delivery of this mitigation will be secured through a S106 agreement and planning conditions, as necessary. Mitigation will need to accord with the spatial and temporal principles set out in the latest Natural England guidance.[1]

Nutrient neutral development could be achieved through (though not limited to):

  • On-site mitigation through sufficient green infrastructure/SUDS/wetlands where appropriate
  • Change of use of agricultural land to a use with less intensive nitrogen/phosphorus input within the site or elsewhere in the catchment, equalling or exceeding the necessary nutrient budget surplus resulting from the development
  • Other off-site mitigation such as the creation of interceptor wetlands, enhancements to wastewater treatment works, upgrades to existing septic tanks, and SUDs.
  • Purchase of mitigation ‘credits’ from an acceptable strategic mitigation scheme elsewhere in the River Test and Itchen catchment (this may include through an approved auction process)
  • Neighbourhood plan identified scheme for Neighbourhood plan allocations
7.23 Mitigation that can be provided locally and within the borough will be encouraged in order to improve the water quality of water bodies and protect associated biodiversity.  The land can also be utilised to contribute towards enhancements required by mandatory Biodiversity Net Gain, where it aligns with the legislative requirements.  The changes in land use agreed upon to mitigate nutrients on a particular piece of land can be used to contribute towards “no net loss”. In order to use the land and associated actions to contribute towards biodiversity net gain, additional enhancements will be required that go beyond the remit of the specified activities for achieving nutrient neutrality. Where possible, mitigation proposals should incorporate opportunities for creating and improving habitats as identified through the government’s forthcoming Nature Recovery Network and the Local Nature Recovery Strategy, and the preference is for mitigation to be provided within the borough.
Implementation and Monitoring

The policy will be implemented through:

  • Advice on, and the determination of, relevant planning applications and appeal decisions.

[1] https://www.basingstoke.gov.uk/submit-a-planning-application Natural England Water Quality and Nutrient Neutrality Advice March 2022