Council could abandon legal advice to unlock thousands of Somerset homes

Around 12,000 homes across Somerset are being held up following the Dutch N court ruling and the resulting Natural England legal advice, with developers having to provide additional mitigation to prevent any net increase in phosphates on the Somerset Levels and Moors.

Somerset Council has been attempting to alleviate the problem on several fronts, negotiating mitigation with developers on individual sites (often through fallowing agricultural land) and trialling several long-term solutions paid for through a central government grant.

Councillor Henry Hobhouse obtained an independent legal opinion in March which stated that Wessex Water’s upgrades of its waste water treatment plants (which will be completed by April 2030) would remove enough phosphates to allow all the delayed homes to be delivered.

More than seven months on, after receiving further legal advice, the council is poised to abandon Natural England’s advice, allowing it to clear its planning backlog and ease the county’s housing crisis.

Here’s everything you need to know:

What is the phosphates crisis?

Phosphates can enter rivers and other watercourses through a number of methods, ranging from fertiliser and animal waste being washed off farmland to human sewage.

Large quantities of phosphates in rivers and lakes can cause eutrophication and large algae blooms, which can deprive plants and animals living in these habitats of oxygen.

The Dutch N court ruling outlaws any developments which increase either phosphate or nitrate levels within Ramsar sites – that is, wetlands or other low-lying areas which are protected under international law.

The resulting legal advice from Natural England, which was published in August 2020, identified 16 “sensitive catchment areas” across the UK where this ruling would apply – including three either in Somerset or on its border.

In addition to the Somerset Levels and Moors (which includes the catchments of the River Brue, the River Parrett and the River Tone), Somerset’s rivers also flow into the River Axe catchment in east Devon and the Poole Harbour catchment in Dorset.

In order to build any form of new development – from houses and commercial units to agricultural barns – the developer and the local authorities would have to agree additional mitigation which would offset the phosphates generated from the development site.

How many homes are currently affected?

Around 18,000 homes in Somerset were originally stopped in their tracks by the Dutch N ruling.

Between April 1, 2021 and March 31, 2025, a total of 5,747 dwellings within the Level and Moors catchment were approved with agreed phosphate mitigation – and there are sufficient ‘phosphate credits’ available to unlock up to a further 5,800 homes.

The homes in these two categories (which amount to 11,547 homes, or roughly the population of Minehead as of the 2021 census) are spread out across the Levels and Moors catchment area, with the former Taunton Deane and South Somerset areas being especially affected.

This still leaves around 6,400 homes which are “awaiting a phosphate solution” – though some of these sites may not be delivered before 2032, and are therefore not being viewed as an urgent priority.

The government has also raised Somerset’s housing target significantly, with its annual requirement rising from 2,669 homes to 3,769 homes – an increase of 41 per cent.

What mitigation is currently being tried?

To date, phosphate mitigation has taken a number of forms at specific sites, including:

Creating new wetlands, which can filter out and absorb phosphates (such as at the Staplegrove urban extension in Taunton)

Fallowing agricultural land, taking it out of active production and potentially replacing it with woodland (such as the Canal Way development in Ilminster)

Upgrading waste water treatment plants, removing phosphates from sewage (such as at the Lowerside Lane site in Glastonbury)

Upgrading septic tanks with package treatment plants, which take more phosphates out before they leave a residential area (such as at the planned Nynehead Road development in Wellington)

Both Somerset Council and private companies have also created ‘phosphate credit’ schemes, whereby the developer will pay for off-site mitigation to offset the impact of new homes – at an average cost of around £34,000 to remove one kilogram of phosphates.

On top of this, the council secured £9.6m in central government grants in December 2023 to fund several projects designed to deliver further mitigation.

Three of these projects are being taken forward – namely:

The creation of new wetlands on either council-owned land or private sites (at a projected cost of £5.6m)

The creation of ‘temporary’ or ‘bridging’ phosphate credits (providing mitigation up to 2030 without fallowing more land) by growing miscanthus grass and trialling new technology (£3.5m)

Upgrading sewage treatment plants near rural council houses in the former Taunton Deane area (£1m)

What about the water companies?

Under the Levelling Up and Regeneration Act 2023 (known colloquially as LURA), water companies were ordered to upgrade their waste water treatment plants to remove larger quantities of phosphates than was originally permitted.

These upgrades must be implemented by May 2031 and must be applied to all waste water treatment plants which serve a population of 2,000 or more people.

Wessex Water has publicly committed to upgrading all the applicable Somerset plants by April 1, 2030, and entered into an agreement with the council to implement “stretch permits” at its Langport, Taunton and Wells sites which will see additional phosphates removed on top of the LURA requirements.

Why does the council want to change approach?

Councillor Henry Hobhouse jointly commissioned (with Somerset Council) a new legal opinion on phosphates from London law firm Landmark Chambers – which was received shortly before the council’s strategic planning committee met on March 17.

In essence, the new legal opinion states that Wessex Water had already removed enough phosphates through its treatment plant upgrades to offset the 18,000 delayed homes – and that there would be enough “headroom” generated by the remaining upgrades to offset thousands more properties on top of this.

Matt Wheeldon, director of infrastructure development at Wessex Water, confirmed this in a letter to the council which was published before its strategic planning committee met in Taunton on October 16.

He said: “The excess phosphorus load we have removed from out-performance against discharge permits would have massively exceeded that arising from 18,000 new homes.

“Looking forward, the excess phosphorus load forecast to be removed from out-performance against future discharge permits will also easily exceed the load being added from 18,000 new homes.

“Out-performance equates to allowing around 205,000 new homes to be built before the phosphorus load discharged meets the permit limit.”

Mr Wheeldon’s position has been supported by Martock-based citizen scientist Dr Andrew Clegg, who has been studying phosphates in the River Parrett catchment for more than three years.

In a statement read aloud to the strategic planning committee, he said: “During the last eight months period at Chiselborough, I have seen the baseline phosphate load (the lowest load) decrease from around 40 kg per day to around 15 kg per day – a drop of 25 kg per day or 14.6 tonnes per year.

“The only factor that has changed in this period is the outflow from two upstream sewage works at Merriott and Crewkerne, both of which had phosphate removal stages installed at the end of last year.”

Taunton resident David Orr said the council’s current approach was “inflicting massive economic and social harm across Somerset” while doing little to actively improve the condition of the Levels and Moors, calling it “a prime example of rules for the sake of rules”.

He added: “We are now recognising and accounting for the significant phosphorus reduction improvements delivered by Wessex Water – improvements that have been funded through the rising water bills paid by all of us.

“This pragmatic approach should finally allow much-needed housing to progress, while we concentrate our efforts on the real challenge: improving the ecological condition of the Somerset Levels and Moors.”

How have councillors responded?

Councillor Simon Coles, who also chairs the council’s planning committee west, said he was in favour of changing approach to ensure much-needed affordable housing could be delivered across Somerset.

He said: “There’s something like 2,800 affordable homes which have stalled, and somewhere between £70m and £100m of Section 106 and CIL contributions that we’re not getting.

“I think there’s a way forward using the new opinion’s methodology. I think we should adopt that.

“We should agree a statement with Wessex Water, Natural England and the Envirnment Agency, recognising the work that Wessex Water has done and is doing, and I think we should therefore start looking to grant planning permissions and getting over his backlog that we’ve got.

“Otherwise, we’re always going to be on the back foot, forever and a day. We need to start leading from the front.

“The alternative is that we are going to have inordinate issues resisting unwanted, undesirable development in the wrong places.”

Mr Hobhouse (whose Castle Cary division has seen significant housing growth over the last decade) added: “Natural England is not in charge. The council is in charge.

“Three years ago, Cornwall Council sent a letter to Natural England pointing out that Bodmin was not in the catchment area of the River Camel, and the nutrient neutrality advise was withdrawn.

“The benefits of removing nutrient neutrality in its current form are: less negotiations by planning officers when developers come in with their plans, easier legal deals, and an increase in community benefits for all of our divisions.

“Castle Cary has had £500,000 removed in community benefits to pay for phosphate mitigations.”

How have officers responded – and what happens next?

Kate Murdoch, the council’s service manager for planning policy and implementation, said that Natural England had ruled that Wessex Water’s upgrades should be used to restore the Levels and Moors to a good condition, rather than for unlocking new homes.

She explained: “These are measures undertaken to bring the protected sites back into a favourable condition, rather than for mitigation for new residential development.

“However, the new phosphate permit limits reduce the phosphate mitigation requirements for new residential developments.”

Lesley Dolan, the council’s principal lawyer and practice manager, said that the council could find itself in choppy waters if it chose to pursue such a course unilaterally.

She said: “It would be ill-advised to go ahead until we have the response from Natural England.”

To this end, Chris Hall, the council’s executive director for community, place and economy, has written to Natural England asking for its view on the council “removing the developer requirements for additional phosphate mitigation”.

Natural England’s response, and any resulting policy change, is expected to come back before the committee by March 2026.