Nutrient Management in Planning and Development

NRW Marine Condition Assessments

NRW’s 2025 marine assessments confirm unfavourable Dissolved Inorganic Nitrogen (DIN) and opportunistic macroalgae condition in Burry Inlet Inner. As a result, developments that increase nitrogen loads must demonstrate DIN neutrality or secure robust mitigation in line with NRW’s marine SAC advice.

Natural Resources Wales (NRW) has published updated Condition Assessments for Marine Special Areas of Conservation (SACs) and Special Protection Areas (SPAs), including the Carmarthen Bay and Estuaries SAC, Burry Inlet SPA, and Carmarthen Bay SPA.

NRW’s 2025 marine assessments show DIN failures in the Carmarthen Bay & Estuaries SAC (Burry Inlet Inner). Developments increasing nitrogen loads must demonstrate DIN neutrality.

These assessments provide the latest evidence on the condition of designated marine and estuarine habitats, including consideration of nutrient pressures.

We are reviewing the findings and waiting on additional evidence from NRW and will provide further information here in due course.

You can access the Condition Assessments and Conservation planning advice via the NRW website.

Indicative DIN Neutrality Catchment Area for Carmarthenshire

These maps have been produced by Carmarthenshire County Council to illustrate the area where dissolved inorganic nitrogen (DIN) neutrality advice currently applies for planning purposes.

It applies only to development proposals connecting to the public mains sewerage network. Development proposals in sewered areas must connect foul drainage to the mains sewer in accordance with Planning Policy Wales (Edition 12, para 6.6.20) and Welsh Government Circular 008/2018.

It is intended to guide developers, agents, and consultees in understanding where nutrient neutrality assessments may be required.

The boundary shown here is based on Natural Resources Wales’ (NRW) published Marine SAC Freshwater Catchments Requiring Nitrogen Neutrality layer (September 2025), refined through local analysis of sewerage catchments in consultation with Dŵr Cymru Welsh Water (DCWW). The refinement excludes land within the NRW zone that is served by sewerage catchments discharging outside the affected marine SAC, and includes land outside the NRW zone that is served by sewerage catchments discharging into the SAC.

NRW have confirmed (9 September 2025) that screening distances for developments not intending to connect to the public sewer network will no longer apply within the NN catchment. NRW have proposed to update their latest guidance to reflect that position. This confirmation has not yet been given in respect of the refined datasets published here. 

Guidance & Limitations

This dataset is an adaptation of the NRW catchment layer for planning purposes. On 9 September 2025, NRW confirmed that screening distances for developments not intending to connect to the public sewer network will no longer apply within the NN catchment, and they propose to update their published guidance accordingly. This position has not yet been confirmed in relation to the refined dataset published here.

Applicants that are not intending to connect to the public sewer network (for example agricultural developments, private treatment systems and separator toilets) should use the NRW Marine SAC Freshwater Catchments Requiring Nutrient Neutrality map.

The map presented here is provided for guidance only. It does not replace NRW’s published nutrient neutrality datasets or formal regulatory advice.

Sewer catchment data has been used internally to refine the boundary but is not published in its own right. Developers should always seek confirmation from DCWW and NRW on drainage arrangements for individual sites.

The boundary may be subject to change as new evidence, monitoring data, or regulatory advice becomes available.