Nutrient Neutrality in the Chesil and the Fleet catchment

Chesil and the Fleet SAC/SPA is located in the Dorset Council area. Dorset Council acts as the lead authority on planning issues relating to nutrient pollution of the Chesil and the Fleet.

Chesil and the Fleet has not been designated by the Secretary of State as a nutrient sensitive catchment because it falls below the size thresholds in the Levelling Up and Regeneration Act 2023. Despite this Natural England have advised us that the habitat site is in an unfavourable condition due to excessive phosphorous and nitrogen levels.

Mitigation

Within this catchment developers will take responsibility for securing nutrient mitigation for their development proposal. Mitigation can be secured:

• on-site or through land in the ownership of the developer
• through an agreement with an accredited third-party mitigation provider
• through a council delivered nutrient mitigation scheme

In all instances, the mitigation will need to be secured in perpetuity through the necessary legal agreements or planning condition.

Decision making in the Chesil and the Fleet catchment

Within the Chesil and the Fleet catchment, there is a need for qualifying developments to demonstrate neutrality for phosphorus and nitrogen. Qualifying development includes:

• any form of development that increases overnight stays within the catchment
• some commercial development that either attract large numbers of people into the catchment (such as a tourist attraction) or where there is a significant discharge into the catchment for example from an industrial process
• development which results in the intensification of agricultural practices, such as an additional cattle barn

Development that increases overnight stays in the catchment may comprise permanent residential development, gypsy and traveller development, care homes, nursing homes, tourist accommodation including both permanent and temporary campsites and hotels.

The boundary of the Chesil and the Fleet catchment is defined within the catchment map. Within this area, it is presumed that surface water arising from qualifying development is likely to increase phosphorous and nitrogen levels within the Chesil and the Fleet. Wastewater from Weymouth wastewater treatment works is discharged offshore from Chesil and the Fleet and therefore does not contribute to nutrient pollution in the habitat site. Where an applicant considers that either wastewater or surface water from their development will not discharge into Chesil and the Fleet they must submit details with their planning application.

The latest Chesil and the Fleet nutrient budget calculator (February 2024) should be used to assess the development’s nutrient budget. Applicants will need to demonstrate that appropriate mitigation measures have been secured to offset the phosphorous and nitrogen arising from qualifying development.

A nutrient neutrality statement must be submitted with any planning application for qualifying development in the Chesil and the Fleet catchment. There are further details on the statement in our local list requirements, but it should include:

• an assessment of whether the proposed development is also ‘qualifying development’
• details of arrangements for managing wastewater and surface water arising from the development
• a nutrient budget calculation for both phosphorous and nitrogen made using the Natural England nutrient calculator for Chesil and the Fleet
• details (including how this mitigation will be delivered and secured in perpetuity) of the mitigation proposed to offset nutrient loading

We have produced a guidance note to assist applicants where they propose to upgrade an existing septic tank or package treatment plant to provide mitigation measures, or where they propose to connect a development to a new package treatment plant. Where relevant, applicants may wish to refer to this note when preparing their planning application.