Legal advice on phosphates sought privately by councillor could open door to 12,000 dwellings

Somerset Council has said it will review its policy on phosphate mitigation after legal advice suggested improvement works by Wessex Water (WW) could allow for planning permission for almost 12,000 new dwellings in the Somerset Levels and Moors.

Three individual legal opinions have been sought on the issue regarding the impact of phosphate levels on planning permissions in the area, with the first being issued by Paul Brown KC of Landmark Chambers in February 2024.

The initial advice, commissioned by the council, concerned the extent to which it is legally possible for Somerset Council to treat past improvements to waste water treatment works by Wessex Water as mitigation for future housing development within the water catchment area of the Somerset Levels and Moors.

Based on the information at the time, Brown concluded that the "headroom" created by Wessex Water's improvements to its waste water treatment works had already been taken up by new developments.

This meant that any new development in the catchment area would require additional mitigation to go ahead, he advised.

However, a member of Somerset Council, Cllr Henry Hobhouse, later sought his own legal advice.

The councillor had identified that some 18,000 dwellings in the area were unable to be delivered due to the absence of a strategic solution to nutrient neutrality.

He had calculated that 3-4 tonnes of phosphorus needed to be stripped out of the waste water treatment works in order to release the homes.

He had also identified that WW had already stripped out between 17.3 and 20.8 tonnes and had undertaken to increase that to 70 tonnes by January 2025.

Cllr Hobhouse privately sought an opinion from Christopher Boyle KC of Landmark Chambers.

Boyle's advice, dated May 2024, concluded that existing and proposed phosphate stripping was "significantly in excess" of the anticipated contribution of the 18,000 stalled dwellings. 

"Consequently, it would be lawfully open to the Council to conclude a favourable 'appropriate assessment' and grant planning permission for the 18,000 stalled dwellings," without reliance on a Natural England-promoted 'off-setting' scheme, he said.

Cllr Hobhouse then presented this advice to the council, leading the local authority and Cllr Hobhouse to commission new advice from both KCs.

The barristers issued their joint opinion last month (10 March), which found that the matter turned on "whether or not phosphate stripping introduced by WW has been directed (at least to the extent of 4t/a) under [Water Industry Strategic Environmental Requirements] to mitigate anticipated phosphate loading from the projected growth".

"On the information before us, it appears that it has –  and very significantly exceeds it (17.3-70t/a). Natural England, however, are reported to have taken a contrary stance. The reasons for that are not apparent to us."

It continued: "The resolution of these matters is not a point of law, but an issue of fact for the council.

"Should the council establish with WW that (at least 4t/a) of the phosphate stripping is for mitigation of anticipated housing, the council may legitimately take that into account in an appropriate assessment for a planning application, depending on the factual circumstances of the catchment, WWTW and development in question."

The council has asserted that 6,200 dwellings are not delayed by nutrients, such as phosphates, leaving 11,800 dwellings to be accounted for by 2032.

Speaking to the BBC, Somerset Council said it accepted the opinion and that council officers will now analyse the legal opinion and use it as a basis for a new policy on phosphate mitigation.

A spokesperson for the council said officers are now working through the next steps “focusing particularly on collating the evidence required, as advised in the opinion”.

The statement added: “As a result, we are not yet in a position to answer the likely questions that this creates and will provide further information as soon as possible.

“For the avoidance of doubt, Somerset Council accepts the opinion.”

Adam Carey