The Planning and Infrastructure Bill - The Legislation We Needed

Zak Simmonds • March 17, 2025

Nutrient Neutrality - An onsite perspective.

Pyramid chart showing mitigation tiers (0-3) with increasing kilogram/year ranges.

Most will agree that a levy system is a practical and logical approach to delivering nutrient neutrality which shall allow developers to build without facing the roadblock of demonstrating nutrient neutrality themselves. However, introducing such legislation in its current form at this current time is potentially damaging if it does not leave scope for onsite assessments and the input of private credit suppliers.


The legislation smacks of a shadow government that has been waiting in the wings far too long and has watched the disastrous handling on nutrient neutrality by the previous government. The Conservative government made ill-considered attempts to scrap nutrient neutrality entirely, posturing over several months which destroyed investor confidence in the market. This is the critical reason that NN effected areas have seen such a low throughput of quality, reasonably priced nutrient credits. Where investor confidence has withstood we are now seeing a good supply of reasonably priced credits which developers can readily afford with reasonable payment terms (see Somerset).


Implementing a levy system at this stage, populated by Natural England or another Delivery Body, simply creates another wave of uncertainty for the private market spanning potentially 18 months until the bill gets royal assent. This will result in another significant period without nutrient credits being available to developers thus resulting in a self-fulfilling prophecy of the private market being unable to meet supply. This prophecy also leads to a skill shortage in the sector as organisations are unwilling to commit resources or hire new staff in such a volatile industry.


Even with the instability, the private sector has managed to deliver significant quantums of mitigation and produce real innovation in the sector. Natural England have not been able to deliver significant quantums of mitigation, particularly in relation to phosphorus, and look posed to pursue spatially intensive arable land reversion schemes in order to generate credits. There is no certainty, at this stage, that the cost of mitigating through the levy will be any less than purchasing mitigation through a private third party, with nitrogen credits sold by Natural England costing more in the Poole Harbour than private credit suppliers elsewhere in the country.


Onsite nutrient neutrality has been a tiring and overwhelming process where minute details are fought tooth and nail with the regulator. However, only through onsite assessments can the Delivery Body be sure that they are providing the correct amount of mitigation for the catchment without over committing resources. We have shaved 20kg/year of phosphorus off a developer's budget on a single site through simple, un-invasive controls that should be considered best practice. We have managed to reduce the liability of a single dwelling development down from 3.0kg/year to just over 0.10kg/year (yes, 3.0kg/year for a single house!). A large proportion of developments simply does not need mitigation, providing the calculations are performed correctly.



If onsite assessments are not continued then there will be no incentive to reduce nutrient budgets through measures such as specifying tailored SuDS treatment trains or utilising top of the range Package Treatment Plants for off-mains proposals. If a developers final nutrient budget can be mitigated at a lower cost than the levy then developers will inevitably seek their own solution. 

When setting a levy one needs to protect our rural communities whilst permitting strategic developments at cost and pace. If a flat levy is implemented then larger developers will likely lobby for a price decrease, where proposals are typically closer to larger settlements with a higher performing Wastewater Treatment Works. To remedy these conflicting interests a banded system must be implemented, with scope for onsite assessments, as outlined in the diagram in this post. This will ensure that development that has no impact shall not pay, that developments with a lower cost per roof pay the least and those with a higher budget pay more, whilst ensuring that the prices in Tier 3 are not preventatively high.


The outstanding supply of private credits/LPA generated credits must be factored into the mitigation stock of the Delivery Plan outlined by the Delivery Body and contribute to the Nature Restoration Fund to kickstart mitigation delivery. For the levy to be a success it needs to welcome private input and supply, both to provide the necessary quantum of mitigation for the strategic mitigation but also for a developer to explore all options available to them. 

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