Animal rights campaigners are urging Michael Gove to stop the construction of the UK’s first fully on-land salmon farm, claiming the decision to give it planning permission was flawed. Animal Equality says an environmental impact assessment (EIA) should have been carried out before North East Lincolnshire council (NELC) gave the green light to the salmon farm in Cleethorpes, which it says would be the UK’s biggest on land or at sea. While government guidance says each case should be judged on its merits, it states that the indicative threshold for an EIA to be appropriate is where a farm is designed to produce more than 100 tonnes of fish a year. The Aquacultured Seafood Ltd development aims to produce 5,000 tonnes of fish a year, but was deemed “unlikely to have significant effects on the environment by virtue of factors such as its nature, size or location”. Animal Equality described the decision as “mind-bogglingly irresponsible”. A legal letter, sent to Gove and NELC by the law firm Advocates for Animals on behalf of the charity, says: “Due to the scale of the project, the uniqueness of it, the location and risks to the local wildlife, the impact of any malfunction, or indeed any unforeseen circumstances, has the potential to be huge and complex. In-depth assessment and clarity is especially important for such a new enterprise, where the impacts remain unknown, anything less will be purely speculative.” The letter says that there are significant risks from water being pumped from the Humber estuary – which is designated as a “wetland of international importance” under the Ramsar convention – then pumped back in after it has been used by the farm to house the fish, as well as from contamination to the surrounding area and wildlife from diseased fish. Official figures suggest that salmon mortality on Scottish farms hit record levels this year. The charity also says the farm “plans to use a treatment company that has only been used in Russia and Slovakia; no data has been published as to whether or not it is working successfully”. The rationale given for not conducting an EIA statement was that the farm is an “on-land and self-contained facility rather than traditional in water”. But Animal Equality says that the planning authority placed too much reliance on assurances from the developer. The charity’s executive director, Abigail Penny, said: “Given the abundant uncertainties and obvious risks, it is scandalous that the committee has allowed the application to get this far, let alone to have given it the green light. The lack of diligence on display is disturbing. The government must step in and stop this from going any further. We will continue to do everything in our power to prevent this monstrous fish factory from being constructed”. The charity has given the Department for Levelling Up, Housing and Communities 21 days to respond. The DLUHC confirmed it had received a letter about the local planning authority’s decision not to carry out an EIA and said it would respond in due course. NELC declined to comment. The Guardian also attempted to reach Aquacultured Seafood for comment. This article was amended on 27 December 2023. An earlier version reported Animal Equality referring to the planned salmon farm as “the world’s biggest”. However, after publication the charity told us it was uncertain over that claim and revised its statement to refer to “the UK’s” biggest such farm.