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Solent nitrogen neutrality: 18 months on, where are we now?
Since our last update on the issue of nutrient neutrality in the Solent we have seen yet another iteration of guidance from Natural England.
Read our last update here.
In addition, the Partnership for South Hampshire’s technical advisers at Wood have published an important update of calculations for nitrate loading from housing growth. However, perhaps the most critical development, following more than 18 months of house building ‘moratoriums’, has been the emergence of several effective mitigation schemes, finally allowing developments to move forward again. Nevertheless, we continue to have concerns about the long-term impacts on the rate of housing growth in the area.
New guidance, little change
Natural England’s fifth version of its ‘Advice on Achieving Nutrient Neutrality for New Development in the Solent Region’ (June 2020) did not contain any significant changes to the advice in the previous version and focused solely on correcting errors. However, this latest advice was accompanied by an official nitrogen budget calculator which should be used and submitted as part of every affected planning application. We would caution that the calculator is not appropriate for all circumstances, for example, the dwelling occupancy rate is locked at 2.4 persons per dwelling. Whilst this may work for general housing applications, and is in line with Natural England’s guidance on average household occupancy rates based on data from the Office for National Statistics, it would not be appropriate in cases of flatted or ‘care home’ development. Where there is good justification for a lower occupancy figure, a bespoke calculator will need to be prepared.
With the recent publication by Wood of the updated calculations of nitrate loading from housing growth, we are expecting a further version of Natural England guidance to be issued early next year.
Strategic nitrate loading figures revised
Wood Environmental & Infrastructure Solutions had previously prepared the Integrated Water Management Study (IWMS) for Partnership for South Hampshire (PfSH) to assess the implications from planned growth on the region’s water resources and water quality. However, this 2018 study focussed mainly on phosphorus as the constraining nutrient. Since then, and based on European case law from 2018-2019, Natural England began recommending the need for developments generating ‘overnight stays’ to demonstrate nitrogen neutrality. This change in emphasis was directly linked to studies of the deteriorating condition, due to nitrates, of the Solent marine sites protected under the Habitats Directive. As a result of the change, PfSH commissioned Wood to prepare an addendum to the IWMS that would look in greater depth at predicted nitrogen loading from housing growth.
The revised calculations showed a small increase in new housing numbers for the period 2018 to 2036, up from 102,234 to 106,816. This equates to an increase of approximately 4.5% in projected housing numbers. However, the new calculations show an overall increase in nitrogen loading at all affected Wastewater Treatment Works (WwTWs) of 6.0% over current (2018) loading. This increase is partly because of Natural England’s recommendation to use a high concentration (25 mg-N per litre) of assumed total nitrates at those WwTWs with no nitrogen permit. A lack of data on total nitrogen levels at these ‘unpermitted’ WwTWs is an area of ongoing uncertainty which is likely resulting in more mitigation being sought than is actually required. Thus, it is positive that Southern Water have agreed to put in place more routine monitoring of total nitrogen levels at WwTWs. However, due to the need to have at least one year’s worth of data, to reduce uncertainty due to seasonal variations, the first complete annual record is not expected until April 2021.
Scenario modelling by Wood, using predicted WwTW monitoring data, suggests that this would result in a lower additional nitrogen loading figure compared to the baseline. In addition, a lower household occupancy rate forecast by the ONS is expected to push average occupancy below the 2.4 persons per household that Natural England currently recommends. We therefore expect the next version of Natural England’s guidance to reflect this change as new data becomes available. This will again help to ensure that developers are not being burdened by an unnecessarily high level of mitigation for nitrates impacts.
A way out at last?
To the relief of at least some developers who have had planning applications stuck as a result of nitrates impacts, there has finally been some effective progress made in establishing mitigation schemes. These are generally schemes aimed at developers with no agricultural land to offer as mitigation. These schemes allow financial contributions to be paid to third parties who use the funds to secure agricultural land and take this out of agricultural use, transforming it into uses less dependent on nitrogen inputs and often with other ecological benefits as well. Pooling funding also allows for a strategic approach avoiding reliance on small piecemeal parcels of mitigation land which is less effective at reducing nitrogen flows to the Solent.
The Hampshire & Isle of Wight Wildlife Trust has successfully established a mitigation site on the Isle of Wight to provide mitigation to affected developments on the island and is also currently benefiting sites in Fareham Borough. This works on a credit system where developers can buy credits that offset their nitrogen burden against the nitrogen reductions from the rewilding of the Trust’s mitigation site. Due to sheer demand for credits, further land is being acquired by the Trust on the Isle of Wight to serve these and other local authority areas in the relevant catchment who wish to participate. A similar credit scheme is being run by the Warnford Estate in the Meon Valley within South Downs National Park to serve developments in their East Hampshire catchment area.
Rather than engage a third party, Havant Borough Council has secured control of Warblington Farm to run its own credit scheme allowing residential development in the borough to proceed whilst delivering a new nature reserve for residents and visitors. Winchester City Council’s Cabinet has also recently resolved to start collecting off-site financial contributions for nitrates mitigation. These funds will be put towards future mitigation solutions that will be delivered by either the council or in partnership with another agency. Meanwhile, Portsmouth City Council implemented one of the first local authority mitigation schemes in November 2019, collecting off-site contributions to put towards improving water use efficiency within the city’s social housing portfolio, albeit as a relatively short-term solution.
Following intensive local lobbying, the Government is also now looking to play its part by investing £3.9 million to establish an online ‘nitrate trading’ auction platform where developers will be able to buy credits from landowners looking to create new and less ‘nitrogen intensive’ habitats. The platform is expected to be rolled out over the next two years and will be delivered jointly between DEFRA, MHCLG, Natural England and the Environment Agency.
In our view these solutions are each to be welcomed as they will certainly help unlock development and support a boost in growth within a region that has significant housing demand. We would hope those local authorities and organisations who have established mitigation solutions will act as sources of inspiration and guidance for other local authority areas who are yet to establish any formal mitigation solution.
As welcome as the various mitigation schemes are, it is disappointing that the partner local authorities within the PfSH have so far failed to agree any meaningful strategic approach that could be applied across the impacted area. Until the promised Government nitrate trading auction platform is implemented, the availability of effective mitigation options remains effectively a ‘postcode lottery’ with developments within some river catchments, including the largest of those affected (the Rivers Test and Itchen) having no current mitigation options available beyond developer provision of agricultural land. Thus, growth in the area continues to be unnecessarily constrained, with consequential adverse impacts on jobs and the local economy at the very time when every bit of support is critical.
Nutrient neutrality and how we can help
We provide regular updates on issues of nutrient neutrality and we remain well placed to advise our clients and guide affected developments through the planning process. We are aware that issues of nutrient neutrality are now affecting developments in other parts of the county, including Somerset, Kent and Herefordshire, and we are able to take the significant expertise we have developed on this issue to assist those with developments in newly affected areas.
If this is something we can help you with please do not hesitate to contact Peter Home or James Cording for an informal discussion.
11 November 2020