Catchment guidance

The Somerset Levels and Moors Ramsar are located in Somerset Council area. The catchment area for this habitat site overlaps part of Dorset Council area. Somerset Council act as the lead authority on planning issues relating to nutrient pollution of the Somerset Levels and Moors. We have been working closely with Somerset Council on these issues to ensure that there is effective joint working across our boundaries.

On 25 January 2024, the Secretary of State designated the Somerset Levels and Moors as a nutrient sensitive catchment for phosphorus.

Mitigation and the Local Nutrient Mitigation Fund

Somerset Council has been awarded £9.6m of grant funding to aid the delivery of nutrient mitigation within the Somerset Levels and Moors catchment. This grant enables mitigation projects to be identified and delivered, and for mitigation credits to be sold. Third-party mitigation providers are also beginning to deliver measures in the catchment areas of the Somerset Levels and Moors.

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 an agreement with Somerset Council when acting as a mitigation provider

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

Decision making in the Somerset Levels and Moors catchment

Within the Somerset Levels and Moors catchment, there is a need for qualifying developments to demonstrate neutrality for phosphorus. 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 Somerset Levels and Moors hydrological catchment is shown on Dorset Explorer and Wessex Water’s wastewater management plan map provides details of the areas served by their wastewater treatment works and where treated wastewater effluent is discharged. Within this area, it is presumed that wastewater and surface water arising from qualifying development is likely to increase phosphorous levels within the Somerset Levels and Moors. Where an applicant considers that either wastewater or surface water from their development will not discharge into Somerset Levels and Moors they must submit details with their planning application.

The Somerset Council nutrient budget calculator (March 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 arising from qualifying development.

A nutrient neutrality statement must be submitted with any planning application for qualifying development in the Somerset Levels and Moors catchment which is also in Dorset Council area. There are further details on the statement in our local list requirements, but it should include:

• details of arrangements for managing wastewater and surface water arising from the development
• a nutrient budget calculation for phosphorous made using the Somerset Levels nutrient calculator for the Levels and Moors
• 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.

The River Axe SAC (special area of conservation), and its tributaries, run through several different administrative areas. The catchment area for this habitat site overlaps part of Dorset Council area. East Devon Council act as the lead authority on planning issues relating to nutrient pollution of the River Axe. We have been working closely with East Devon Council on these issues to ensure that there is effective joint working across our boundaries.

On 25 January 2024, the Secretary of State designated the River Axe as a nutrient sensitive catchment for phosphorus.

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 an agreement with a council when acting as a mitigation scheme provider

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

Decision making in the River Axe catchment

Within the River Axe catchment, there is a need for qualifying developments to demonstrate neutrality for phosphorus. Qualifying development includes:

• 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 River Axe hydrological catchment is shown on Dorset Explorer. Applicants should contact South West Water separately for further details of the areas served by their wastewater treatment works and where treated waste water effluent is discharged. Within this area, it is presumed that wastewater and surface water arising from qualifying development is likely to increase phosphorous levels within the River Axe. Where an applicant considers that either wastewater or surface water from their development will not discharge into River Axe they must submit details with their planning application.

The latest River Axe nutrient budget calculator (May 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 arising from qualifying development.

A nutrient neutrality statement must be submitted with any planning application for qualifying development in the River Axe catchment which is also in Dorset Council area. There are further details on the statement in our local list requirements, but it should include:

• details of arrangements for managing wastewater and surface water arising from the development
• a nutrient budget calculation for phosphorous made using the Natural England nutrient calculator for the River Axe
• 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.

The River Avon SAC (special area of conservation) runs through several different administrative areas. The catchment area for this habitat site overlaps part of Dorset Council area. Wiltshire Council act as the lead authority on planning issues relating to nutrient pollution of the River Avon. We have been working closely with Wiltshire Council on these issues to ensure that there is effective joint working across our boundaries.

On 25 January 2024, the Secretary of State designated the River Avon as a nutrient sensitive catchment for phosphorus.

Mitigation and the Local Nutrient Mitigation Fund

Wiltshire Council has been awarded £9.8m of grant funding to aid the delivery of nutrient mitigation within the River Avon catchment. This grant enables mitigation projects to be identified and delivered, and for mitigation credits to be sold. Third-party mitigation providers are also beginning to deliver measures in the catchment of the River Avon.

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 an agreement with Wiltshire Council when acting as a mitigation provider

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

Decision making in the River Avon catchment

Within the River Avon catchment, there is a need for qualifying developments to demonstrate neutrality for phosphorus. 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 River Avon hydrological catchment is shown on Dorset Explorer and Wessex Water’s wastewater management plan map provides details of the areas served by their wastewater treatment works and where treated wastewater effluent is discharged. Within this area, it is presumed that wastewater and surface water arising from qualifying development is likely to increase phosphorous levels within the River Avon. Where an applicant considers that either wastewater or surface water from their development will not discharge into River Avon they must submit details with their planning application.

The latest River Avon nutrient budget calculator (May 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 arising from qualifying development.

A nutrient neutrality statement must be submitted with any planning application for qualifying development in the River Avon catchment which is also in Dorset Council area. There are further details on the statement in our local list requirements, but it should include:

• details of arrangements for managing wastewater and surface water arising from the development
• a nutrient budget calculation for both phosphorous made using the Natural England nutrient calculator for the River Avon
• 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.

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 an agreement with Dorset Council when acting as a nutrient mitigation provider

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 hydrological catchment is shown on Dorset Explorer and Wessex Water’s wastewater management plan map provides details of the areas served by their wastewater treatment works and where treated wastewater effluent is discharged. 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:

• 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.