Whenever we speak to our customers about the biggest challenges they are facing, nutrient neutrality is usually always on their list.
Now, if you’re not operating in one of the 74 Local Planning Authorities (LPAs) currently impacted by nutrient neutrality, it may not be on your radar. But with 42 LPAs being added as recently as March 2022, it’s a constraint that all developers should be aware of.
What is nutrient neutrality?
Across the UK’s river system and coastal waters, certain nutrients are reaching dangerous levels – mainly phosphorus (affecting freshwater) and nitrogen (affecting saltwater). If the concentration of these nutrients gets too high it can cause an unhealthy growth in some plant species which harms wildlife in the river catchment areas.
The UK is one of the most nature-depleted countries in the world, but it’s not just an issue facing developers in the UK. Other countries with intense agricultural practices, like the Netherlands, have been forced to grapple with the issue of nutrient neutrality too. For the purpose of this blog, however, we will be solely focusing on the UK.
Nutrient neutrality aims to prevent the impact of additional nutrients within the water catchment by reducing or offsetting these substances. But that’s a little tricky as they’re present in all sorts of wastewater, including from sewage treatment works and agriculture. With the latter causing some big issues for residential developers.
In order to secure planning permission, developers need to be able to prove that their proposed development will not increase the levels of these nutrients. Or as Richard Broadbent, Director at Freeths put it on our recent webinar on the subject:
“Nutrient neutrality is a means of ensuring that a plan or project does not add to existing nutrient burdens so there is no net increase in nutrients as a result of the plan or project.”
However, adding new people to an area means adding new nutrients to a catchment, so developers need to find ways to ensure that impacts are minimised as far as possible (on-site mitigation), and then ensure that any residual effects are offset – either through further on-site treatment work, through off-site treatments, or via offsetting.
For developers, who are unable to source additional land for on or off-site mitigation, there is also the option to pay into one of the emerging mitigation schemes. Typically, these financial contributions are pooled and then used strategically to take larger chunks of farmland out of agricultural circulation.
However, in some local authorities (particularly those added most recently) there aren’t fully developed solutions for mitigation – which is causing further confusion and delays for developers.
Later on in the blog, we’ll take a look into mitigation options.
Where does nutrient neutrality apply?
There are currently 74 LPAs impacted by nutrient neutrality.
In LandInsight, you can now use our bespoke nutrient neutrality dataset to see exactly which areas in each LPA are affected and link through to more detailed information provided by the council, including:
Whether mitigation is possible within the planning authority
A link to the mitigation scheme or position statement, from the planning authority
Nutrients of concern within the impacted area
You can see a short demo of LandInsight's nutrient neutrality data in action during the webinar recording.
If you’re operating in these areas, you’ll need to include mitigation to demonstrate nutrient neutrality if you’re developing any of the following:
Typically, it applies to those with a net dwelling increase, not conversions or replacements – but it’s worth verifying this with the LPA in question beforehand.
How is nutrient neutrality impacting developers?
Time, cost, and uncertainty are the obvious impacts that spring to mind.
However, nutrient neutrality is also throwing up some other challenges for developers.
- Changes to nutrient budget – the update of March 2022 has resulted in new nutrient calculators being introduced. Some developers may need to rerun the figures through the new calculators.
- Increased competition for sites – with huge swathes of land now constrained by the impacted authorities, there’s more competition for the sites outside of the catchment areas, and more competition for potential offset sites. SMEs in particular are feeling the squeeze as larger housebuilders are now forced to go for smaller unit plots that they typically wouldn’t consider.
- Reduction in housing delivery – perhaps the most serious (and long-term) issue is the constriction of housing supply. Research by Savills determines that housing delivery could be cut by more than half in areas where nutrient neutrality was introduced. This in turn will drive up the price of new builds due to lack of availability.
So, as a developer, how do you find out whether mitigation is required? First you need to calculate how much phosphorus or nitrogen your development would be producing.
How do you calculate nutrient neutrality?
The aim is for each LPA to have a catchment-specific calculator that can be used to check whether your proposed development will be nutrient neutral.
The calculator estimates the population change that will result from the new dwellings – based on unit size and the national average of dwelling occupancy.
Next, you’ll need to fill in the information on how the wastewater produced from your development will be treated. This will then calculate the total nutrient loading that will result from the new dwelling.
The projected nutrient loading levels following development will be compared to the pre-development land use. If the latter is the same as the former, then it will be considered zero value, and the site will be nutrient neutral.
But if your development is going to be producing more nutrients than the site was previously, you’ll need to undertake further mitigation – either on-site or off-site.
Nutrient neutrality mitigation solutions
As a developer, you’ll need to decide whether on-site or off-site mitigation is the best option. The former gives you more control, but may not be possible with the land you have available. Or where the designated site or impacted waterway is.
Below, we break down some on-site and off-site mitigation options for nutrient neutrality that Jack Potter, Head of Nature Based Solutions, shared in our recent webinar.
On-site mitigation methods:
Sustainable drainage systems (SuDS) – installing these drainage systems on your development site can effectively treat and extract nutrients from urban runoff. They can also be factored into your nutrient budget and enable you to create a bespoke calculation for your leaching rate.
Permeable paving – incorporating permeable pavement on, for example, driveways, can also improve water quality. Both SuDS and permeable paving are favoured by many councils for managing urban runoff, so you’ll probably be familiar with these already.
Low water usage appliances – some appliances like toilets or washing machines have low water usage models. If less water is being used in your developments, then less water will be discharged to sewage treatment works, ultimately leading to less water with nutrients in it. If low-flow devices are relied upon to ensure nutrient neutrality is achieved, you can expect the retention of these devices to be conditioned as part of the planning approval process.
Packaged water treatment plants – these pre-manufactured systems can be used on-site to treat wastewater flows.
Off-site mitigation methods:
Constructed wetlands – certain reeds grown at the bottom of wetlands have proven to be effective at the removal of nutrients. Creating one of these wetlands can count as a form of mitigation. If your site allows, this could also be undertaken as on-site works.
Land use change – this form of mitigation can be quite complicated as it requires you to take an existing piece of intensely farmed land and bring it out of production. Natural England only accepts changing the use to woodland as it prevents further output coming from the land. If you’re investigating this option, you’d be well advised to ensure that the potential substitution site has a current intensive agriculture licence.
Buffer strips – this is an emerging strategy involving buffering impacted watercourses to trap or prevent some of the runoff seeping back into them. It’s currently under negotiation with Natural England but could be very helpful in unblocking some of these phosphorous impacted areas.
Interaction of offset sites with other natural resource systems
Known as ‘stacking’ or ‘bundling’, this relates to the use of one piece of land for offsetting or providing multiple ecosystem services at the same time. For example, turning an arable field into woodland, and then claiming nutrient neutrality, biodiversity net gain, and carbon units for this same site.
‘Stacking’ refers to the practice of selling ecosystem services to different development schemes, ‘bundling’ is where you sell them to the same scheme. Natural England are currently recommending that this is allowed.
Natural England’s nutrient mitigation scheme
In March 2023, Natural England launched their own mitigation scheme – enabling developers to buy credits to offset nutrient pollution.
These credits can be put towards mitigation, like creating a wetland or woodland, to balance out the nutrient pollution that will be caused by your future development.
At launch, the scheme is only available within the Tees catchment area but more areas are expected to be added in the future. One credit is currently priced at £1,825. Which as Jack Potter shared is “basically at cost” and could just act as a temporary solution “until the private market establishes itself” and the price of credits is pushed up.
Nutrient neutrality in practice
Hopefully, you have a good idea of what nutrient neutrality is by now, but we are going to take a look at a couple of real-world examples of LPAs who are having to navigate these issues.
The Solent is often referenced when talking about nutrient neutrality, so we’ll be using this as a point of comparison for Norfolk – where these constraints have more recently come into place.
The Solent catchment includes some of the South of England’s largest coastal cities, including Southampton and Portsmouth – and they have been facing nutrient neutrality rules since 2018.
In 2020, 10,000 homes in these two cities were put on hold and many more planning applications got stuck in the system.
As a result, LPAs in the Solent catchment have failed to meet their housing delivery targets – from 2016 to 2021 they averaged only 63% of the net additional dwellings needed.
Savills' data also shows that since the rules were put in place in 2018, the number of consents plunged downwards – 50-72% below the highs they were experiencing before. All of these factors are likely to have a long-term impact on delivery and the affordability of homes in the Solent.
There are, however, some success stories. Particularly around the credit-based mitigation schemes which have been set up in the area. Credits have been used to buy farmland equalling over 450 acres in the Solent area – and exceeded the level of nitrates instructed to be removed by 25%.
Although a real challenge for developers at times, the progress of reversing the impact of nitrates, rewilding agricultural land, and restoring biodiversity can be taken as a small victory.
As of March 2022, all authorities in Norfolk now have to factor nutrient neutrality into their planning process. It’s already had a significant impact in the area “with 42,000 new homes delayed in the greater Norwich area alone.”
The sudden introduction of nutrient neutrality could also cause hold-ups on a wider scale as Greater Norwich’s Local Plan may be delayed – adding to the uncertainty around delivery on a county-wide level.
Some comfort can be taken from the fact that they aren’t the first LPA to go through these challenges. And in many ways, a precedent has already been set by LPAs like those operating in the Solent.
In addition to this, nutrient neutrality calculators and some funding sources have already been established so some of the guesswork has been taken out of it.
But it still could take months to come up with a Norfolk-wide mitigation strategy – leaving many developers unsure how long it will take until they can break ground.
And this is very much the case for developers up and down the country. The lack of clarity and timeframes on when there will be a resolution are freezing up the whole delivery system and causing a lot of frustration.
Watch our on-demand webinar for more tips on how to mitigate nutrient neutrality
During the session, they covered:
- Recent updates to nutrient neutrality
- Examples of solutions and mitigation strategies
- Wider context of environmental and policy constraints
Register now to watch on-demand:
Other content you might be interested in:
- Nutrient neutrality: three things you should be considering
- How to get planning permission in the Green Belt
- Four steps to find and fund sites