Nitrate Neutrality: Solutions from the Solent

The problem of nitrate and phosphate neutrality is not new to the development industry. The Solent region was one of the first areas to hit the news in late 2019 with articles on how algae blooms within the river catchment was blocking up to 10,000 planned homes.

The issue centres around the fact that for many years, elevated levels of nitrates and phosphates within certain river catchments, such as the Solent have deteriorated water quality and have led to eutrophication, which has detrimental impacts upon marine wildlife. Not only has this had a serious impact upon fish and bird habitats, excessive concentrations of nitrate filtering into drinking waters has also been linked to human health conditions such as methemoglobinemia (blue-baby syndrome).

Previously from 2019, 32 Local Planning Authorities (‘LPAs’) around the Solent region, Herefordshire, Kent, Somerset and Cornwall were issued with advice from Natural England that the development of new homes and other such forms of overnight accommodation such as hotels and student accommodation should not proceed unless evidence indicates these will be nitrate ‘neutral’. The Home Builders Federation calculated that across the 32 LPAs approximately 60,000 homes have been delayed.

This issue was further exacerbated on the 16th March this year, when Natural England issued further advice to 42 additional LPAs  in various river catchment areas around the UK (particularly in the south and south-west, the north-west and in Norfolk).  Consequently, this has stopped development until a solution is found demonstrating that  development proposed will be nitrate and phosphate neutral.

The impact on housing delivery is therefore a serious concern for the Government, LPAs and developers, with many of the affected areas facing an acute shortage of market and affordable homes. Nitrate Neutrality is also an issue which cannot simply be weighed in the planning balance in the same way as other material planning considerations, rather it stems from EU law. Habitats Directive 92/43/EEC imposes a ‘precautionary principle’ which means that proposed development schemes must demonstrate that they will not result in significant effects upon the integrity of the Natura 2000 designated sites. As such, until robust solutions have been demonstrated, there is effectively an absolute moratorium on new residential and overnight accommodation in the affected areas.

As the Solent region was one of the first affected areas, there have been lessons learnt about how nitrate neutral housing can be delivered. According to Natural England, some 3,000 ‘nitrate neutral’ homes have so far been delivered as a result of partnerships between LPAs, developers, landowners and third-party bodies such as local wildlife trusts through the initial impacts being calculated using its calculator that establishes the level of mitigation or offsetting required. This means there is cause for optimism that a solution can be found to deliver the tens of thousands of homes currently on hold.

Solutions which have so far been identified, include onsite measures or offsite measures or a combination of the two. Onsite measures may include reducing nitrates through drainage features (such as reedbeds, wetlands and SuDS features) or by installing local sewage treatment plants (which can be very expensive) to attempt to reduce nitrates at source. These measures will have varying degrees of success depending on the scale of development involved; however, in many cases these may not be sufficient on their own. 

A more effective solution is likely to be offsetting (offsite solutions). The approach which has been adopted in areas such as around the Solent has been for developers or partnerships to purchase arable land which is then taken out of agricultural production and then typically managed for biodiversity conservation purposes. By taking land out of production it is no longer subject to nitrate pollution arising from fertilizer application, thereby offsetting nitrate impacts from new homes (principally because of increased wastewater effluent). 

However, whilst there have been some more successful cases of where offsite contributions have helped to unlock development; (for example, ‘Partnership for South Hampshire’s’ established offsetting scheme), in practice it is not straightforward to acquire land and achieve agreement with the relevant LPAs as to what the offsetting schemes should involve. It requires available land in the right locations, which means finding a willing landowner who can sell or lease land or sell offsetting units to take land out of production and at the right price. 

The amount of agricultural land potentially required at a national level could also be vast. To give an example, Carter Jonas is currently advising on a 400 home development which may require a 14ha pig farm or 56ha of regular arable land to offset nitrate impacts through the planting of a woodland. The resulting loss of productive arable land is also difficult to reconcile particularly with the conflict in Ukraine restricting global food supply. In the longer term, a multifaceted approach is likely to be required, involving a wider range of stakeholders. Studies by the Environment Agency indicate that the agricultural industry is responsible for approximately 70% of nitrate pollution and 25%-30% coming from wastewater from urban development and industrial sources. With phosphates on the other hand, approximately 70% of pollution in UK watercourses comes from urban development and industrial sources with most of the remainder from agriculture. 

Developments will need to maximise treatment at source alongside further innovations in wastewater treatment. Alongside this, there may also need to be further changes in agricultural policy and legislation to reduce negative externalities associated with livestock and fertilizer application. Nitrate offsetting will increase demand for land, competing with other land needs, including food and energy production and housing and development. Nevertheless, it may be complementary with other natural capital markets such as biodiversity net gain and carbon offsetting, which can often be ‘stacked’ and therefore offers opportunities for farmers and rural landowners to diversify estate income, whilst delivering positive environmental outcomes. Achieving efficiencies in terms of reduction in food waste and innovation in agriculture (such as investments in vertical farming and alternative proteins) will also form part of the solution by helping to free up land.

Many LPAs and developers are awaiting further guidance from Natural England on nitrate neutrality as feedback to date has been limited. The DLUHC have invested funding to tackle the issue and a quick and easy solution has not yet been rolled out. However, there are some promising cases where development schemes are starting to move forward in the Solent region through the establishment of nutrient trading platform. For LPAs and developers in other affected areas of the country, establishing a trading market for offsetting may therefore be the best way forward and offsetting credit schemes should be accessible, simple to use and viable.