Nutrient neutrality is an environmental mitigation requirement that applies to new development within the catchments of designated habitats (Special Areas of Conservation, Special Protection Areas, and Ramsar sites) that are in an unfavourable condition due to excess nutrient loading — primarily nitrogen and phosphorus.

The requirement arises from the Conservation of Habitats and Species Regulations 2017 (the “Habitats Regulations”). Where a Habitats Regulations Assessment concludes that additional nutrient loading from development could have a likely significant effect on a designated site, the applicant must demonstrate nutrient neutrality — meaning the development will result in no net increase in nutrient discharge.

Natural England has identified over 70 catchments across England where nutrient neutrality applies, affecting tens of thousands of planned homes. The affected waterbodies include rivers, estuaries, and lakes that support internationally important habitats.

The nutrient neutrality calculation involves:

Existing land use: Determining the current nutrient export from the site based on its land use (e.g. agricultural land exports significant nutrients through fertiliser application)
Proposed development: Calculating the additional nutrient load from increased wastewater (via the sewage treatment works) and changes in land use
Net change: The difference between existing and proposed nutrient loads. If the net change is positive (more nutrients), mitigation is required.

Mitigation options include:

On-site measures: taking agricultural land out of production, creating wetlands, or implementing package treatment plants
Off-site nutrient credit schemes: purchasing credits from mitigation providers who deliver nutrient reductions elsewhere in the catchment
Upgraded wastewater treatment: working with the water company to improve treatment at the receiving sewage works

Aegaea provides nutrient neutrality assessments across affected catchments, calculating nutrient budgets and identifying cost-effective mitigation strategies.

Nutrient Neutrality