Ecologists doubt Norfolk's £2,675-per-home nature levy will cut chalk stream pollution

Multiply the two headline figures and they agree. At £2,675 a house, 15,780 houses come to £42.2m ^[1], close to the government's hope of about £42m ^[9]. That sum is revenue. The thing it doesn't tell you is the effect size.

The pooled cash is to be spent on measures that help offset pollution from new homes ^[7]. An offset is a comparison between two quantities: what the new homes add to Norfolk's rivers, and what the funded work takes back out. The published account of the plan does not include an estimate of either.

Natural England, which is leading the project, argues that pooling is the improvement. "Instead of tackling pollution piecemeal, site by site, we can now deliver conservation measures that make a real difference for rivers, wetlands and wildlife across Norfolk," said Marian Spain, its chief executive ^[12]. Angela Eagle, the Environment Secretary, calls the scheme a "win-win" for development and nature ^[8].

Norfolk's chalk streams, often described as England's rainforests, are particularly vulnerable ^[22]. The ecologists' objection is about whether habitat spending protects them ^[3]. Sally Haines, chief executive of the Chartered Institute of Ecology and Environmental Management, said that while the actions outlined in the plan would improve ecological habitats in the area, they would not necessarily address the pollution that will be going into the water ^[4]. "Unless you do that, you are not going to get good nature recovery," she said ^[5].

Mark Dye, a chalk stream campaigner with the Gaywood River Revival group in west Norfolk, said that "if you are polluting a chalk stream or a river and you're putting more and more pollution into that river, and not seeking to address the underlying causes of that, then it's only going to get worse" ^[20].

A housebuilder and an ecologist both play down new homes, for different reasons. Steve Turner, executive director of the Home Builders Federation, said pollution from farmers was a bigger issue than new homes, and criticised water companies for not investing in infrastructure to stop sewage entering rivers ^[21]. Haines called it a "fallacy" to blame environmental concerns as the main stumbling block to building, pointing to the availability of materials and labour, and to land prices ^[13].

If Turner and Haines are both right, the levy charges a smaller source of river pollution to release homes held back by other things. I think the habitat gains it buys are likely to be real. The critics' point stands until the final plan shows how much of the rivers' pollution the funded work removes.

Norfolk Wildlife Trust said it needed more time to review the proposals, and that it was worried about wider changes to planning rules ^[18]. "We are concerned that it weakens existing protections for Norfolk's nationally and globally important wildlife sites such as chalk streams, wetlands and valley fens," said Eliot Lyne, its chief executive ^[19].