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Nutrient neutrality and planning applications

Area affected in Cornwall

The area affected extends from:

  • between Camelford and Tintagel in the north
  • following close to the A30 from Bolventor to Bodmin and
  • just south of the A30 from Bodmin to Roche to parts of St Breock Downs and
  • between Wadebridge and Egloshayle in the west.

These areas are subject to phosphate mitigation requirements. You can find an overview map of the areas using this link: 

Cornwall Council Interactive Map

The catchment area has a map of the applicable wastewater treatment works (WwTWs).  Please note:

  • Developments within the catchment area that will drain to a WwTWs within the catchment will need to complete stages 1-3 of the calculator.
  • Developments located outside of the catchment area but that will connect to a WwTWs that drains to the catchment should not complete Stages 2 and 3. This may apply to certain developments in Bodmin, Delabole and St Mabyn.
  • Where a site is located within the hydrological catchment but drains to a WwTWs outside of the catchment (ie Luxulyan and Wadebridge) then Stage 1 should be set so that the occupancy rate is zero.

Phosphate Budget Calculator

Our updated phosphate budget calculator (version 3) is available (March 2024).

The Levelling-up and Regeneration Act 2023 (LURA) created a new duty for water companies in designated catchments. This includes the River Camel. This duty will address pollution at source. The duty on water companies will ensure wastewater treatment works (WwTW) serving a population equivalent over 2,000 meet specified nutrient removal standards.

South West Water is required to upgrade Nanstallon, Scarletts Well and Camelford WwTWs before 1 April 2030. The calculator has been updated to reflect these specified nutrient removal standards from 1 April 2030. We have previously consulted Natural England (NE) on the Cornwall Council calculator. They had no objection to the finalised version. The most recent change is to reflect legislation and no further consultation with NE is required.

You should:

  • use the calculator to find out the phosphate level for your proposal
  • submit this information to support your planning application.

You will need to rerun the phosphate budget calculations if you have a pending planning application which drains to one of the affected WsTWs.  If you have any queries, please speak to the case officer.  A planning application will only be able to proceed if:

  • the proposed development is phosphate neutral or
  • you can identify and secure mitigation to make it neutral.

The calculator contains a help section to assist with the stages of the process. The video provides a step by step guide on how to use the calculator.

Phosphate Budget Calculator

River Camel Phosphate Calculator tutorial video

More help with the calculator

The completion of the calculator and the nutrient neutrality statement should be done by a competent person with the relevant experience.  A specialist ecological or environmental consultant will help you: 

  • complete the phosphate calculator
  • research and design any required mitigation

Natural England also offer a Discretionary Advice Service which you could use. We will be adding more guidance to help use the calculator in response to queries we receive.

The Constructed Wetlands Hub is now live.  It is a joint site from the Rivers Trust and Constructed Wetland Association.  The site brings together a wealth of information and data on constructed wetlands.

The Constructed Wetlands Hub provides useful information on how to design and find the best location for wetlands.  It only applies to 'treatment' wetlands.  It does not apply to informal wetlands eg farm wetlands and SuDS wetlands.

The Framework Approach for Responding to Wetland Mitigation Proposals sets out:

  • the design process
  • how to calculate nutrients mitigated by the wetlands and
  • what % of the modelled mitigation you can use from the outset.

Natural England published: Introduction to Freshwater Wetlands for Improving Water Quality - JP044. The final section focuses on:

  • integrated constructed wetlands (ICWs) and
  • the site specific considerations that affect their design and implementation.

Next steps

When you have used the calculator:

  • you will have an understanding of how much mitigation a development will need
  • you can now consider what your options are for mitigation.

Our phosphates flowchart sets out how to proceed: Does the phosphate calculator result show an increase in phosphate?

A proposal for development needs:

  • a Habitats Regulations Assessment (HRA) which shows that the development will avoid or have a neutral effect on nutrient pollution OR
  • an HRA and an appropriate mitigation strategy if the development will have an adverse effect on the protected site

to be acceptable. 

This will help you move forward with your proposal: 

Validation requirements: please submit a nutrient neutrality statement with the calculator results. You can find the information on the Validation updates page.

Small scale thresholds and nutrient neutrality principles guidelines: These interim guidelines help to:

  • determine if a project will have a likely significant effect
  • consider nutrient neutrality.

If you wish to rely on these guidelines, you need to assess how the development accords with conditions a) to h).  A competent person with the relevant experience should do the assessment.  Please provide the completed assessment.

We have updated our local Validation list.  Please see the Validation Guide for more details.

Chemical dosing of package treatment plants: Natural England have advised that PTPs requiring chemical dosing should only be used where it can be robustly justified and only if carried out by a British Water Accredited Service Technician. This also includes other suitably qualified professionals working for an established, experienced management company.

Where chemical dosing is proposed developers will need to provide a robust, evidenced justification:

  • for why chemical dosing is necessary
  • that dosing can be managed appropriately and
  • why a non-chemical (biological) PTP cannot be used.

Where agreed chemical dosing is appropriate, developers will need to show that:

  • a management plan for dosing and other maintenance is in place
  • dosing will only be carried out by experienced, accredited professionals through a service agreement. This will be secured by a planning condition or legal agreement for the lifetime of the development.

These additional costs for management and maintenance of systems requiring dosing may be prohibitively expensive for smaller developments.  Officers will discuss these requirements with developers prior to proceeding. Developers will need to provide:

  • the make, model and capacity of the proposed PTP and
  • information on required dosing, management and maintenance

in order to allow the Council to carry out an Appropriate Assessment.

You can find out what development is affected on our Types of development and applications affected page.

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