Nutrient neutrality in Cornwall


Phosphates in the River Camel catchment area

The River Camel Special Area of Conservation is designated under the Habitat Regulations 2017.   The quality of the natural environment is of national and international significance.  Natural England considers the natural habitats of the River Camel to be unfavourable.  This is due to excessive phosphates. Good water quality is critical to how the river functions. You can find more information using this link: Temporary pause on developments - River Camel

This means greater scrutiny of proposed developments that may increase nutrient loads. Natural England sent a letter to the Council on 15 April 2021. It set out concerns about the high levels of phosphates in the River Camel. Developments will need a Habitats Regulations Assessment (HRA).

Cornwall Council paused decision making in the River Camel catchment area. We cannot approve new developments unless they can show they are nutrient neutral.  Our phosphate budget calculator is part of the HRA process.

Phosphate Budget Calculator

Our phosphate budget calculator is available.  You can use it for proposed developments in the River Camel catchment area. It provides a rapid calculation of net phosphate loading from developments.  This includes phosphate offsetting calculations for on and off site locations. It is a clear decision making tool for the Local Planning Authority and developers.

You should use the calculator to find out the phosphate level for your proposal.  You need to submit this information to support your planning application. A planning application will only be able to proceed if:

  • the proposed development is phosphate neutral or
  • you have identified mitigation (to make it neutral) that you can secure.

Natural England released a new calculator for completing a nutrient budget on 16 March.  The Natural England advice acknowledged that a transitional period would be required where existing tools and methodologies were in place.  We are discussing the calculator with NE and will update the Cornwall Council calculator shortly.  Applicants may then need to rerun their phosphate budget calculations.  Until advised otherwise, please continue to use the Cornwall Council calculator. We will provide further updates on these pages.

We know other calculators are available.  But the Cornwall Council calculator uses local data to provide an accurate phosphate calculation.  Regarding any calculations based on a different Local Planning Authority's calculator:

  • we would not accept them
  • you would need to repeat them using this Camel specific calculator.

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

The area of risk

New development in the River Camel catchment area may increase phosphates in the river. You can find a map of the area 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.

More help with the calculator

If you need help to complete the calculator, we recommend using a specialist consultant.  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.

Banking coefficients

Stage 3 of the calculator asks for bespoke banking coefficients.  These are for constructed wetlands that can be evidenced.

Advice: Wetlands banking coefficients are controlled by many variables including:

  • volumes
  • hydraulic loading rate
  • retention times
  • area.

There is currently no official guidance on how to get bespoke values.  Natural England hope to provide this guidance in March.  Until then, please contact Natural England through their Discretionary Advice Service.

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?

This will help you move forward with your proposal:

Validation requirements: we are updating our local validation list.  You need to 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.

You can find more information on the Considering an application in the River Camel catchment area page.

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

Latest news

Draft Solutions Report

Cornwall Council has published its draft solutions report for the River Camel phosphates issue.  You can read the report using this link: River Camel Phosphate Mitigation Solutions Report

The draft River Camel Solutions Report sets out a range of potential mitigation solutions. If implemented they could help reduce the amount of phosphates entering the river.

Please note: The phosphate calculations used in this report to:

  • determine the likely phosphate removal of solutions and
  • estimate the phosphate loading from development

come from the Cornwall Council River Camel Phosphate Calculator (published November 2021).

Since doing this work NE have published further guidance (16 March 2022) for LPAs.  This included a new calculator for the River Camel catchment.  We consider that our original Cornwall Council River Camel Phosphate Calculator remains the most accurate way of calculating phosphate loading.  But this may mean we need to amend our calculator to align with the new NE guidance.  This may result in some calculations needing to be amended.  We will be discussing this with NE. It may take some time to finalise.

We want to continue to progress our work on strategic mitigation.  The Solutions Report remains in draft as there may be some change in the phosphate figures.  This does not change the underlying analysis of the most appropriate mitigation in the River Camel catchment.  On that basis we are proceeding to:

  • publish this report and
  • continue to work on the next stage.

This will be developing an implementation strategy for the solutions taken forward by the Council.

Further letter from Natural England (March 2022)

Cornwall Council received a communication from Natural England.  This contains a 25-page letter with guidance and tools to be used by LPAs regarding nutrient neutrality.  The letter from Natural England only affects the River Camel.  Agents and applicants should continue to use our calculator at present. 

You can find updates and more information on this issue on the following page:

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