Reaching nitrate neutrality

11th December 2020

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Charlie Hammett

A number of local stakeholders have been trying to unplug a planning backlog caused by nitrogen pollution on the south coast. Catherine Early reports

In June 2019, the fate of 10,000 new homes was thrown into limbo after a decision by the European Court of Justice meant that councils had to immediately halt all planning permissions. The ruling against the Netherlands concerned water quality and appropriate assessments, and meant that in areas where a habitat's conservation status was already 'unfavourable', activities that would add further nitrogen pollution should not be authorised.

Nitrogen had been a problem for several years in the Solent, which contains special protection areas (SPAs) and special areas of conservation (SACs) under the EU Birds and Habitats Directives. Natural England cites the Solent region's water environment as one of the UK's most important for wildlife.

The pollution has caused eutrophication, with mats of algae forming over the mudflats, starving water and sediments of oxygen, and killing animals. They also form a barrier to the birds that feed off invertebrates in the mud, and smother the seagrass beds and saltmarshes, risking erosion and damaging their ability to sequester carbon. The pollution comes from agricultural run-off, as well as background pollution with no known source. In legal advice issued to local authorities, Natural England acknowledged that the amount coming from new homes and tourist accommodation was small, but since it would still add to the existing problem, such development could not be allowed unless it was 'nutrient neutral'.

It also published guidance on how this could be achieved (, including a methodology for calculating a nutrient 'budget' for a new housing development, against which plans to mitigate the impact could be assessed by local authorities. The guidance is being continually updated.

“We've understood the principle of offsetting for a long period of time – we just decided to try and apply it to nitrates“

The offsetting solution

There is no single method for achieving nitrogen neutrality, and local authorities, water companies, farmers and the local wildlife trusts are all working on solutions.

Hampshire and Isle of Wight Wildlife Trust (HIWWT) has bought a 40-hectare farm in Wootton on the Isle of Wight, where it will rewild the land to prevent soils containing fertiliser entering the Solent. It has worked out a credits scheme whereby developers can pay it to offset nitrates from new development via the reduction from its farm. “We've understood the principle of offsetting for a long period of time – we just decided to try and apply it to nitrates,“ says John Durnell, head of conservation at the trust. “We've had interest from councils and developers, we're just looking to scale it up.“

The agreement was complex to draw up, as it is hard for a planning authority to enforce a mitigation measure outside its borough. The legal framework contains elements of section 106 of the Town and Country Planning Act and section 32 of the Local Government Agreement, so Isle of Wight Council can carry out enforcement on behalf of another local authority or delegate it back to them.

The trust's motivation for the project is to protect wildlife on the Solent while creating new habitat – not, he stresses, to help housing development. “We have an opportunity to take intensively managed farmland that is pretty horrendous for wildlife and turn it into wildlife-rich area.“ The trust is also fearful that planning delays caused by pollution will encourage the government to dismantle environmental protections after the Brexit transition period. “If they do that, the impact on the Solent will be small compared to the impact on all the SPAs and SACs around the country,“ he says. “We want to find a good scheme that enables us to show the government that nature-based solutions are doable and economically deliverable.“

Authorities are also working on solutions via the Partnership for South Hampshire (PfSH). A popular option is upgrading the water efficiency of council housing and requiring stringent water efficiency for new homes. Councils can then use wastewater reductions as 'credits' to enable new building. The strategy is being considered by local authorities including Eastleigh, Havant, Fareham, Gosport and Southampton.

Some councils are considering buying farmland to create credits schemes, similar to the HIWWT's project. These include Havant Borough Council, which in September confirmed that it had bought a farm to offset all nitrogen from its planning application pipeline. Warblington Farm is to be transformed into a nature reserve to provide replacement habitat for Solent waders, brent geese and curlews, and will be run at no extra cost to the council or its residents, since maintenance will be paid for by contributions from developers offsetting their nitrates.

Who pays?

In September, the government announced that it would invest £3.9m in an online nitrates trading auction platform, through which housing developers will buy credits to pay for habitats such as meadows, woodlands and wetlands in order to prevent nitrates from new housing reaching the Solent.

Housebuilders are pleased that such schemes are beginning to unlock the planning backlog, says Andrew Whitaker, planning director at the Home Builders' Federation. However, in his view, developers are being forced to pay to solve a problem they have not caused – he believes it is down to water companies to treat wastewater from housing before it enters the Solent. “If we're already paying water providers to upgrade infrastructure to deal with housebuilding, then having to pay again for credits is double payment for one problem,“ he says.

Joff Edevane, growth planning lead at Southern Water, says its hands are tied. Business plans for the next five years had already been finalised with Ofwat as the issue came to the fore, he says. “We're victims of timing. There's no flexibility to go back and ask for more cash, it's fixed for five years.“

The regulator is carrying out investigations to calculate what proportion of the problem Southern Water is responsible for. If it is only a small proportion, there would be little point in upgrading its infrastructure because it will not bring about much improvement, says Edevane. Whitaker warns that if developers are forced to pay for nitrates pollution mitigation, councils will have to reduce developer contributions for other issues in order to keep sites viable – with the casualty being affordable housing. “We'd rather have some kind of clear way of dealing with the issue at a strategic level,“ he says.

Thinking long-term

Edevane says that it may make more sense to incentivise farmers to change land management practices, as building new infrastructure would increase greenhouse gas emissions during construction and operation.

He favours a scheme being undertaken in Poole Harbour. Wessex Water worked with farmers to develop the EnTrade scheme, which pays farmers per kilogram of nitrogen saved through good farming practices. These can include planting cover crops to suck up nitrogen and prevent soil being washed away, explains Wessex Water senior catchment manager Adrian Moore. The utility hopes this will avoid the need to build new treatment works. “We've been fairly successful – we have a 40-tonne target, and other than the first year when we were trialling it, we've overachieved,“ he says. “In some years we've offset up to 70 tonnes.“

In June, the government awarded £150,000 to the Poole Harbour Nutrient Management Scheme, which it will use to develop tools such as EnTrade. Farmers hope this will avoid the area being designated as a Water Protection Zone, which would regulate their practices much more tightly.

Some authorities in the area are also considering buying credits from farmers using developer contributions for new housing, Moore adds. He believes the scheme could be used for other pollutants in other locations. “It might be phosphate or sediment or carbon – the principles are the same. It could become a form of income for farmers – they will be able to sell offsets to businesses and water companies. It's nitrogen at the moment, but crack that and hopefully the rest will fit into place.“

Catherine Early is a freelance journalist.

Image credit: Getty Images

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