Are you planning development in a Nutrient Neutrality area without realising it? Nutrient Neutrality applies in 27 catchments in England, and at its peak, the Home Builders Federation estimated that 160,000 homes were held up as a result. In these areas, new development that adds overnight accommodation, such as homes, student housing or tourist accommodation, must show it will not increase the phosphorus or nitrogen reaching a protected river, lake, wetland or estuary.
This guide lists every affected catchment, the nutrient each one needs to mitigate, what has changed since the rules were introduced, and how developers can move forward.
What is Nutrient Neutrality?
Nutrient Neutrality means a new development must not add to the nutrient load reaching a protected site. Phosphorus and nitrogen from wastewater feed algal blooms that strip oxygen from the water and harm the plants and wildlife these sites were designated to protect. Where a protected site is already in poor condition because of nutrient pollution, Natural England advises that planning authorities can only approve new development if the extra nutrients it creates are offset. Find out more about what Nutrient Neutrality is.
Developers show this with a nutrient budget. It calculates how much phosphorus, nitrogen or both the finished scheme will add each year, measured in kilograms, and that figure is then mitigated within the same catchment.
How many areas are affected?
Natural England first asked planning authorities to apply Nutrient Neutrality in seven catchments, including the Solent, Poole Harbour and Stodmarsh. In March 2022 it extended the approach to 20 more, bringing the total to 27 catchments. Between them, they cover 31 protected sites, and the advice went to 74 local planning authorities. Some of those authorities have since merged or been reorganised, so the council names you see today may differ from the original advice.
Is there a Nutrient Neutrality map?
Natural England published a national map of the affected catchments alongside its March 2022 advice, and most affected planning authorities publish their own catchment maps showing the exact boundaries. Our interactive Nutrient Neutrality map lets you check your site’s location and see indicative pricing in one place.
Which catchments need phosphorus, nitrogen or both?
Fifteen of the 27 catchments need phosphorus mitigation only. They are the River Avon in Wiltshire, Hampshire and Dorset, the River Axe on the Devon, Dorset and Somerset border, the River Camel in Cornwall, the River Itchen in Hampshire, the River Lambourn in West Berkshire, the River Lugg in Herefordshire, the River Mease where Leicestershire, Derbyshire, Staffordshire and Warwickshire meet, the River Wensum in Norfolk, the Somerset Levels and Moors, the Peak District Dales in Derbyshire, and Roman Walls Loughs in Northumberland.
The other four phosphorus catchments are in Cumbria: the River Eden, the River Kent, the River Derwent and Bassenthwaite Lake, and Esthwaite Water.
Eight catchments need both phosphorus and nitrogen. They are the Broads in Norfolk, Stodmarsh on the River Stour in East Kent, Chesil and the Fleet in Dorset, Hornsea Mere in the East Riding of Yorkshire, the River Clun in Shropshire, and three sites in Cheshire and the surrounding area: Oak Mere, Rostherne Mere and the West Midlands Mosses.
Four catchments need nitrogen only: the Solent, Poole Harbour, Lindisfarne in Northumberland, and Teesmouth and Cleveland Coast. The River Itchen flows into the Solent but is a separate phosphorus catchment, so some sites there need both.
Catchment boundaries do not follow council borders, so always check your exact site against your planning authority’s map.
Overlaps matter too. The River Wensum is a phosphorus catchment, but it drains into the Broads, so many Wensum sites also need nitrogen mitigation. The Wensum and Broads calculators have been merged to reflect this.
What has changed since 2022?
Catchments are reviewed as evidence improves. In May 2024, Natural England confirmed that new development in Poole Harbour no longer needs to be neutral for phosphorus, because planned treatment works upgrades will deliver the reduction the harbour needs. Nitrogen neutrality still applies there. The River Kent catchment boundary in Cumbria was revised in July 2024. In February 2026, Natural England confirmed changes to the River Eden catchment that took Carlisle, Brampton, Wetheral, Great Salkeld, Lazonby, Calthwaite and High Hesket outside it, because planned treatment works upgrades are expected to solve the nutrient problem there. The River Camel catchment boundary in Cornwall was also revised in February 2026.
Two wider changes are shaping the picture. Under the Levelling-up and Regeneration Act 2023, treatment works serving more than 2,000 people in catchments designated as nutrient sensitive must meet tight limits of 0.25 mg/l for phosphorus and 10 mg/l for nitrogen by 1 April 2030. Sixteen of the 27 catchments are designated, so the upgrades will not reach every affected area. The Government estimated the upgrades would cut phosphorus loads from treatment works in affected catchments by about 69% and nitrogen by about 57%, which is why many nutrient budgets now show separate figures for before and after 2030. The Planning and Infrastructure Act 2025 also introduced Environmental Delivery Plans, which give developers a different way to meet their obligations once a plan is in force for their area. Natural England has said it intends to prepare 16 nutrient plans, and the first draft, covering parts of Norfolk, was open for consultation from 17 September to 27 October 2026. Until a plan is in force for your area, the existing Nutrient Neutrality process continues to apply.
What does it mean if your site is in an affected catchment?
If your site falls within one of these catchments and you add overnight accommodation, your planning authority will need to see a nutrient budget and a plan to offset the result before it grants permission. That applies to new homes, conversions, holiday lets and other overnight accommodation. It can also apply at the reserved matters stage or when discharging conditions on an older permission.
Mitigation has to come from the same catchment as your site. A credit generated in Norfolk cannot offset a development in Kent, and the same rule applies between any two catchments.
How can developers mitigate nutrients?
Developers can offset nutrients in several ways, from measures on the development site itself to buying nutrient credits from a supplier in your catchment. Natural England also runs its own Nutrient Mitigation Scheme, which currently sells credits in the Tees and Poole Harbour catchments. Credits are often the quickest route, because the mitigation is already in place or being delivered and the supplier provides the paperwork your planning officer needs. Read more about Nutrient Neutrality for developers.
Credits can be temporary, covering a set period such as the years before the 2030 upgrades, or permanent, covering the lifetime of the development. Your nutrient budget will show which you need.
Where does National Rivers Consortium supply nutrient credits?
We generate credits primarily by replacing old septic tanks with modern treatment plants, which cuts the phosphorus and nitrogen reaching local rivers. We create and use every credit within the same catchment and secure it with a long-term legal agreement.
We supply phosphorus and nitrogen credits across all Nutrient Neutrality catchments. If we already have credits in stock, we can secure them quickly. Where we don’t, we build supply inside your catchment, which usually takes 2 to 3 months. You can check your site and see indicative pricing on our catchment map.
Frequently asked questions
How do I know if my site is in a Nutrient Neutrality catchment?
Your planning authority’s Nutrient Neutrality page will usually include a catchment map. You can also check your site on our catchment map. If your site is close to a boundary, ask your planning officer to confirm.
Does Nutrient Neutrality apply to a single new home?
Yes. Any development that adds overnight accommodation in an affected catchment can be caught, including one new home, a holiday let or a self-contained annexe, depending on how your planning authority assesses it.
How many homes are held up by Nutrient Neutrality?
Estimates vary. The Home Builders Federation estimates around 160,000 homes delayed at various planning stages, while the previous government estimated around 100,000.
Can I use nutrient credits from a different catchment?
No. Mitigation must be delivered in the same catchment as the development because it must benefit the same protected site.
Will Environmental Delivery Plans replace nutrient credits?
Not straight away, and not entirely. A plan applies only once it is in force for a particular area. Until then, the existing Nutrient Neutrality process continues. Once a plan is in force, it gives developers another way to meet their obligations, but in most areas it won’t be the only option. You can still use nutrient credits, and for some schemes the EDP levy may cost more than credits, so it’s worth comparing both before you commit. Check your catchment and indicative pricing on our catchment map.