Following recent court rulings Natural England is raising objections in regard to water quality in various locations across the country.

Concerns over the effects of nutrient enrichment within some European designations (SPAs/SACs), including those in Poole Harbour and the Solent have existed for many years. However, recent rulings from the European Court of Justice mean that Natural England is now responding more robustly to plans or projects that will result in further nutrient loading to European designations which are already at an ‘unfavourable conservation status’ with respect to their water quality. These apply to many SPAs and SACs across England, including those in the Poole, Solent, Stour and Wye catchments.

To inform decision making, Natural England has issued new guidance of how new development sites should meet strict requirements to achieve nutrient neutrality within the Solent catchment. Most new development results in an increased amount of sewage and surface water runoff, entering protected rivers, estuaries, and marine areas, via the local Wastewater Treatment Works. Nitrogen and Phosphorus contained in this effluent in turn causes eutrophication (excessive richness of nutrients in a body of water). Where European designations are present, this nutrient loading can cause a long-term deterioration in the condition of the sensitive features for which the SAC/SPA/Ramsar is designated, including in respect of aquatic plant communities, mudflats and sandbanks and the bird populations that depend on them.

Examples of where water quality is causing an issue for development sites

Solent European Sites

New guidelines from Natural England (Advice on Achieving Nutrient Neutrality for New Developments in the Solent Region) set out a methodology for calculating a ‘Nitrogen Balance’ for each proposed development, and apply to all housing developments as well as those including other types of overnight accommodation such as hotels and tourist attractions. Where there is a net increase in Nitrogen loading as a result of the development then mitigation is required to offset this.

The nutrient calculations consider the additional input through sewage and surface water runoff, and then allow a deduction for land that is being taken out of agricultural production. Account is also taken of the type of Wastewater Treatment Works permit that is in place.  Some developments, especially greenfield sites that result in the loss of intensive agricultural land, may achieve nitrogen neutrality with few additional mitigation measures being put in place. Elsewhere, any nitrogen surplus would need to be mitigated for, either by on-site measures (such as overprovision of green space) or off-site, e.g. by reaching agreements for agricultural land elsewhere to be taken out of production.

It is likely that Local Planning Authorities will need take on the responsibility for central delivery of these mitigation measures (to ensure their function in perpetuity), although at present no mechanism exists, with the arrangements being left to the individual developer. There is currently significant pressure on Authorities within the Solent catchment to develop a coherent strategy and mitigation scheme for addressing new development. Havant Borough Council has produced a Position Statement jointly written with East Hampshire District Council to cabinet urging them to provide a ‘central’ solution to the approach to Nitrogen Neutrality.

In terms of current solutions, Portsmouth City Council has published an ‘Interim Nutrient Neutral Mitigation Strategy for New Dwellings’ which provides a solution based on the improvement of water efficiency measures within the Council’s existing housing stock. In addition, the Hampshire and Isle of Wight Wildlife Trust has launched a scheme which provides strategic mitigation options by the removal of land from agriculture.

Stour Catchment

A nutrient calculator is being developed by Canterbury City Council, on the advice of Natural England, which will take into account Nitrogen and Phosphorus, about which we expect to see an announcement soon. The solution might also involve the development of a strategic interceptor wetland designed to provide a natural sink for phosphates. In the meantime, developers are being asked to propose bespoke mitigation solutions.

River Wye

Natural England is advising that the existing Nutrient Management Plan for the Wye is not adequate to stop further deterioration in water quality with regard to phosphate levels. In the absence of a reliable central mitigation strategy, the onus appears to be on individual developers bringing forward schemes within the Lugg and Wye catchments in Herefordshire.  Such site-specific mitigation measures might include taking off-site land out of agricultural production, providing reedbeds and larger areas of public open space and fitting enhanced water efficiency measures to new buildings. An interim approach sets out a number of thresholds which have been agreed between Natural England, Herefordshire Council and the Environment Agency, within which developments are considered to meet the requirements of the Habitats Regulations.

Poole Harbour

The Poole Harbour SAC suffers from algae growth resulting from high nutrient levels and perhaps has the most established mitigation scheme, having been in place since 2017, which enables developers to fund off-site mitigation through CIL and S106 payments. An SPD ‘Nitrogen Reduction in Poole Harbour Supplementary Planning Document’ sets out how the four councils (Borough of Poole, North Dorset District Council, Purbeck District Council and West Dorset District Council) will mitigate the impact of nitrogen on Poole Harbour. New development can only proceed if it mitigates 25% of the additional nitrogen it produces, and the developer has 4 options to choose from 1) Providing alternative technologies, 2) increasing the size of SANG, 3) taking council-owned land out of production, or 4) purchasing land elsewhere and taking it out of production.

Matters to bear in mind and next steps

• Early consideration should be given to the nutrient status of proposed developments, so that allowances can be made for over-provision of green space e.g. as SANG.
• Other land owned by developers, provided it falls within the same catchment for the most part, could provide a means by which off-site mitigation is made available.
• Brownfield sites are more likely to be more problematic than greenfield sites because they will not result in any agricultural land being taken out of production.
• Ultimately the best way to secure provision of mitigation for long term housing growth is for this to be taken into account by Water Companies when preparing and agreeing their Asset Management Plans (AMPs), to include the required level of investment in wastewater treatment to ensure compliance with the Habitats Regulations. This process can be influenced by Natural England, but is lagging too far behind to allow adequate mitigation to be secured for current development proposals to be mitigated.
• A number of private companies (such as EnTrade) have started to develop new on-line market places for the delivery of mitigation such as nutrient offsetting.

Aspect Ecology is working in all the above regions and we can provide advice as how to steer a way through the water quality issues within the framework of the Habitats Regulations.