On 16 March 2022, Natural England notified Dorset Council of their updated advice for development proposals that have the potential to affect water quality resulting in adverse nutrient impacts on internationally protected habitats sites. This advice applied to the catchments of five habitats sites which together cover a large part of the Dorset Council area. The advice was that Dorset Council should “carefully consider the nutrients impacts of any new plans and projects (including new development proposals) on habitats sites and whether those impacts may have an adverse effect on the integrity of a habitats site that requires mitigation, including through nutrient neutrality.”
The catchments within Dorset that this updated advice related to are:
- Poole Harbour – Nitrogen and Phosphorus nutrient deposition
- Somerset Levels and Moors – Phosphorus nutrient deposition
- River Avon – Phosphorus nutrient deposition
- Chesil and The Fleet – Nitrogen and Phosphorus nutrient deposition
- River Axe – Phosphorus nutrient deposition
Although the issue of nutrient pollution is not new, Dorset Council is working with the other councils across each catchment and with Natural England to understand the implications of this updated advice for future development.
This early work is ongoing and as things progress this web page will be updated.
The Natural England updated guidance includes a Generic Nutrient Neutrality Methodology for calculating nutrient loads in each of the habitat site catchments in our area and a catchment calculator for each catchment. These tools are provisional and the methodologies and assumptions within them will need to be reviewed to reflect local circumstances. In some instances, local methods and calculators have already been developed to calculate nutrient loading from development. Pending our detailed review and in the interim, all developments will need to demonstrate nutrient neutrality.
We have provided more specific guidance on this matter for each of the catchments which include:
Further information and guidance from Natural England is available:
- Nutrient pollution: reducing the impact on protected sites - GOV.UK (www.gov.uk)
- Nutrient Neutrality – a summary guide
- Natural England Water Quality and Nutrient Neutrality Advice
- Nutrient Neutrality principles
- Natural England Nutrient Neutral Generic Methodology
Poole Harbour
The councils in Dorset have published a methodology for calculating Nitrogen loads from development and a mitigation strategy for calculating and delivering Nitrogen mitigation projects. Natural England’s guidance also refers to Phosphorus. We are seeking clarification from Natural England around the implications of their guidance for the existing Nitrogen load calculation methodology and mitigation strategy.
In the interim period all developments will need to demonstrate nutrient neutrality (Phosphorus and Nitrogen) or await formal clarification on our position in respect to this issue. You can access:
- The Natural England Poole Harbour nutrient budget calculator
- Poole Harbour nutrient budget calculator guidance
- The Poole Harbour catchment map
- Nitrogen Reduction in Poole Harbour SPD Adopted
Somerset Levels and Moors
The local Phosphorus calculator: Phosphates on the Somerset levels and moors (somersetwestandtaunton.gov.uk) should be used to calculate nutrient loads. All developments will need to demonstrate nutrient neutrality for Phosphorus.
River Avon
The Natural England River Avon nutrient budget calculator should be used to calculate phosphorus loads. All developments will need to demonstrate nutrient neutrality for Phosphorus using these tools:
Chesil and The Fleet
The Natural England Chesil and The Fleet nutrient budget calculator should be used to calculate nutrient loads. All developments will need to demonstrate nutrient neutrality for Phosphorus and Nitrogen using these tools:
River Axe
The Natural England River Axe nutrient budget calculator should be used to calculate Phosphorus loads. All developments will need to demonstrate nutrient neutrality for Phosphorus using these tools: