Nutrients are essential to the maintenance and growth of our ecosystems and enabling organisms to flourish. However, in this instance, it is possible to have too much of a good thing…

The issue of nutrient neutrality has plagued the UK planning system since early 2019, when Natural England advised a number of authorities in the Solent region to halt the approval of new housing applications, unless nutrient neutrality could be adequately demonstrated. The geographical scope of this advice has since extended to include Kent and Somerset with many other authorities under threat of being affected in the future. It is estimated that plans for over 30,000 homes across England are currently in limbo due to this issue.

The problem – new residential dwellings will increase the levels of nutrients being discharged into the catchment of protected sites, throwing the careful balance of these ecosystems off, resulting in degradation and loss of these protected sites.

The solution – at the moment not 100% clear…

As this issue grows, Natural England, along with local authorities and other key stakeholders are exploring a range of options to deliver strategic mitigation options to break the housing delivery deadlock.

Ideas include converting agricultural land (another major source of nutrient pollution) into strategic wetlands which would be funded through developer contributions for ‘nutrient credits’ to off-set nutrient levels discharged from developments. Whilst this option would assist developers unable to deliver mitigation on-site, these credits could be expensive and have viability implications for many smaller sites. There is also a limited amount of land which is likely to be available for such uses, and therefore it is unlikely to be able to fully address the existing backlog, let alone any future projects.

Large-scale projects may be able to mitigate this on-site through construction of package treatment plans or wetland areas to offset the increase in nutrient runoff generated by the development before it enters the wider wastewater treatment network. However, most wastewater treatment works, whilst leaching nutrients into ecological designations, are still operating within the permit levels agreed with the Environment Agency, and therefore have no obligation to reduce nutrient outputs. Upgrades in the affected areas are anticipated but are not scheduled to begin until the mid-2020s and therefore cannot be relied upon to address the issue now.

While long-term strategic solutions are a way off, pressure continues to build at all levels to collaborate and find simple solutions to break this deadlock. In the meantime, sites are considered on an individual basis and Iceni are advising on several schemes experiencing this issue. If you are also affected or would like to know more, please do not hesitate to get in touch.