The role of planning authorities in assessing the environmental impacts of proposed developments is especially vital when considering nutrient-sensitive river Special Areas of Conservation (SACs). These areas, designated under the Conservation of Habitats and Species Regulations 2017, mandate that planning authorities conduct a Habitats Regulations Assessment (HRA) to evaluate the potential effects of any development on these protected sites.
Wales is home to nine river ecosystems designated as SACs, including the Afonydd Cleddau, Eden, Gwyrfai, Teifi, Tywi, Glaslyn, Dee, Usk, and Wye. These rivers support some of the country’s rarest wildlife, such as Atlantic salmon, freshwater pearl mussel, white-clawed crayfish, and floating water-plantain. The conservation objectives for these rivers are detailed in Core Management Plans (CMPs) managed by Natural Resources Wales (NRW). The primary nutrients of concern in these ecosystems are phosphorus and ammonia. Human activities, notably agriculture and wastewater discharge, elevate phosphorus levels, leading to nutrient enrichment or eutrophication, which can cause significant ecological damage. An assessment published in January 2021 revealed that over 60% of SAC river catchments in Wales failed to meet revised water quality targets for phosphorus. Although ammonia levels generally meet targets, they still require careful monitoring.
Planning authorities must take into account the nutrient impacts of proposed developments on water quality within SAC river catchments. Developments that increase nutrient levels, such as new housing or agricultural enterprises, have the potential to harm these sensitive ecosystems. However, new developments may be authorised if they can demonstrate that they will not further deteriorate water quality or undermine the SAC’s conservation objectives. To achieve this, developments must adhere to principles such as nutrient neutrality, where they either do not contribute additional nutrients, have no pathways for nutrients to enter the SAC river environment, or implement measures to achieve nutrient neutrality. It is essential to understand the dynamics of phosphorus and ammonia, as phosphorus tends to accumulate in river systems, requiring catchment-scale management, while ammonia, which decays more rapidly, can be managed at the water body level. Planning authorities should also seek independent advice where necessary to ensure compliance with the Habitats Regulations.
The HRA process involves two principal stages: the Test of Likely Significant Effect and the Appropriate Assessment. The initial screening assesses whether a development could affect an SAC, and if a significant effect is indicated, a more detailed Appropriate Assessment evaluates the potential impacts on the SAC’s conservation objectives. Certain developments can be screened out as not likely to have a significant effect on a river SAC, such as those that do not increase nutrient levels in wastewater, improvements to existing water quality discharges, and services or facilities for a local population already connected to existing sewers.
Agricultural developments involving organic manures and slurries can contribute to nutrient levels in SAC rivers. However, some agricultural activities, such as covering existing yards or roofing manure storage, are not likely to have significant effects. Conversely, proposals involving livestock housing or new manure stores should undergo an Appropriate Assessment. Non-residential developments, such as tourist accommodations or large retail sites, which attract populations from outside the SAC catchment, may lead to increased nutrient discharges and require further assessment. Domestic extensions that do not create independent living accommodations are generally unlikely to increase nutrient discharges and can typically be screened out.
For new developments proposing connections to public sewers, planning authorities should seek confirmation from sewerage undertakers about the capacity to treat additional wastewater within permit limits. If the treatment works meet the revised nutrient targets, a conclusion of no likely significant effect may be drawn. When connection to a public sewer is not feasible, private sewage treatment systems can be considered. Small discharges to ground, built to relevant standards, are unlikely to have significant effects, whereas larger discharges or those not meeting criteria should undergo an Appropriate Assessment.
Mitigation measures should be assessed during the Appropriate Assessment stage. Planning authorities should seek evidence from developers demonstrating that proposed measures are effective, reliable, and legally enforceable. Furthermore, all Local Development Plans (LDPs) should be screened for potential significant effects on river SACs. Policies that increase nutrient loading should be subject to an Appropriate Assessment. Where wastewater treatment works lack capacity, planning authorities should consider nutrient neutrality or other mitigation measures. Relevant case law, such as the Dutch nitrogen case and the Compton and Wyatt cases, can provide additional clarity on assessing nutrient impacts on SACs.
By adhering to these principles and guidelines, planning authorities can ensure that developments do not compromise the conservation objectives of these vital ecosystems. Their role is critical in protecting nutrient-sensitive river SACs, thereby preserving the biodiversity and ecological health of these invaluable natural resources.
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