Nitrogen nutrient neutrality across Pembrokeshire

Introduction

In June 2025, Natural Resources Wales (NRW) published new evidence on the condition of Welsh European marine Special Area of Conservations (SACs). These conditions assessments informed the publication of updated Conservation Advice Package which set out the conservation objectives for the SACs. More information on Natural Resources Wales / Condition assessments for Welsh European marine sites (EMS) (opens in a new tab) is available. These updates have been put in place to help Wales meet the obligations of the Conservation of Habitats and Species Regulations 2017 (the Habitats Regulations). In particular, the assessments identified Dissolved Inorganic Nitrogen (DIN) concentrations as being a key contributing factor to water quality failures. Those sites that are relevant to Pembrokeshire are:

The Pembrokeshire Marine SAC
The Cardigan Bay SAC
The Carmarthen Bay and Estuaries SAC

Dissolved Inorganic Nitrogen (DIN) and Nutrient Neutrality

The indicator for habitat failure for the Pembrokeshire Marine SAC is the concentration of Dissolved Inorganic Nitrogen (DIN) in its various forms (nitrate, nitrite and ammonia). The assessments consider DIN exceedances alongside secondary performance indicators such as excessive macroalgal growth. Hence, the priority is to reduce nutrient loading in affected areas. Diffuse sources (agricultural run-off, pollution incidents and private non-treated sewage) are thought to be largely responsible for this issue.

The map below shows the area within Pembrokeshire where nutrient neutrality for nitrogen applies. This includes all land hydrologically connected to the Milford Haven Inner waterbody. As a result, most of Pembrokeshire falls within the affected catchment, with the exception of some coastal area, which are largely within the remit of the Pembrokeshire Coast National Park Authority.

Please note that the map provides a general overview and may not capture the full complexity of hydrological connections and drainage pathways. Developers should always seek confirmation from DCWW and NRW on drainage arrangements for their sites. This includes in consideration of any relevant screening distances that apply for developments not intending to connect to the public sewer network.

Map

Marine SAC Freshwater Catchments Requiring Nutrient Neutrality

Alternatively, please refer to the NRW Marine SAC Freshwater Catchments Requiring Nutrient Neutrality map (opens in a new tab).

Habitats Regulations Assessments

The Conservation of Habitats and Species Regulations 2017 (as amended) impose strict legal requirements, and incorrect interpretation or decisions can have serious consequences. Planning permissions granted in breach of these rules are unlawful and highly vulnerable to judicial review and quashing orders.

If a planning application is approved without a compliant Habitats Regulations Assessment (HRA), the decision issued would be unlawful and would leave the Authority open to legal challenge. Developers may face costly delays, reputational damage, and in some cases, requirements to halt works or carry out retrospective mitigation.

Under the Habitats Regulations, the council can only approve plans or projects (including planning applications and the Local Development Plan) where the HRA concludes there is no likelihood of a significant effect on internationally protected ecological sites.

For an HRA to be valid, the Local Planning Authority (LPA) must be able to demonstrate, beyond reasonable scientific doubt, that mitigation measures will prevent any adverse effect on the integrity of the protected site. These measures must be fully effective before any additional nutrients are introduced into the catchment (for example, before new homes are occupied). Natural Resources Wales, as the statutory nature conservation body, must be consulted on the findings of an Appropriate Assessment, and their response must be taken into account.

Development Management Implications and Guidance

Following advice from Natural Resources Wales (NRW) (opens in a new tab) and in line with case law, the Local Planning Authority has adopted a precautionary approach. This begins with screening development proposals to determine whether a full Habitats Regulations Assessment is required.

Alterations and extensions to existing dwellings, proposals that do not increase nutrient discharges, or developments that reduce nutrient discharges can generally be screened out. Planning applications for such development types are unaffected and can continue to be granted permission.

NRW advises that, while each case must be considered individually, developments that increase nutrient discharges are likely to require a full HRA. This includes:

Residential development that adds new nutrient loads to the catchments.

This includes the creation of independent living accommodation, a separate planning unit and/or a change in use, where it can no longer be said to be ancillary to the main residence.

Non-residential development servicing populations form outside the SAC catchment who are not already connected to existing sewer systems discharging within the SAC. Examples include

Tourist accommodation (hotels, guest houses, bed and breakfasts, self-catering facilities, camping and caravan sites).
Large commercial or industrial developments (conference facilities, major retail sites, tourist attractions).

In such cases, further assessment is required to determine whether the proposal would adversely affect the integrity of the riverine or marine SAC.

As NRW have advised, a conclusion of no adverse effect on site integrity may be drawn in a Habitats Regulations Assessment, where any plans or projects in these areas with the potential to increase nutrient discharges can secure appropriate mitigation and demonstrate nutrient neutrality for nitrogen. Currently, it is evident that the public wastewater network will not provide the option for any mitigation in the form of nitrogen removal, preventing nutrient neutrality from being achieved this way. As such developers will need to look at offsetting and/or nature-based mitigation solutions.

To supplement the abovementioned NRW advice, Pembrokeshire County Council has worked with partners to produce a Developer Handbook (opens in a new tab) to provide information and support for developers. The handbook should be used alongside the Welsh Government Nutrient Budget Calculator (opens in a new tab). This tool is used to calculate the nutrient mitigation requirement for developments within the affected catchment.

Developers can use these tools to work out the nitrogen load that proposals would generate and identify what proportionate mitigation options may be suitable.

Developments which wish to utilise mitigation measures must provide a completed version of the Nutrient Budget Calculator for their development upon the submission of a planning application.