A farming company has been fined for carrying out unauthorised work to a river that damaged the habitat of protected water voles.

Dredging and drainage work carried out by Paul Rackham Ltd on a stretch of the Little Ouse had caused a “significant adverse effect on wildlife”, Norwich Crown Court was told.

The company faced three charges, including acting in contravention of an environmental permit, for work it carried out near Lodge Farm Estate at Gasthorpe, between Thetford and Diss.

It was also charged with two breaches of the Wildlife and Countryside Act by damaging a shelter of water voles and a breeding site of the European protected species.

Formerly part of the Riddlesworth Estate, Lodge Farm, covering more than 1,000 acres and including a historic farmhouse overlooking the river, was sold in 2018 after being put up for sale with a price tag of £9.5m.

The court was told the company had subsequently dredged a stretch of the river, which marks the border between Norfolk and Suffolk, without first seeking the necessary environmental permit.

It also felled 25 trees, removed vegetation from the river channel and installed drainage pipes and ditches.

Environment Agency officers visited the site in February 2019 and told the company to stop work and that a permit would be needed requiring flood and drainage risk assessments and a study of the environmental impact.

Officers then carried out a habitat survey while a biodiversity officer produced a report that found the work had caused “extensive harm”.

In her judgement, Judge Maureen Bacon said the Environment Agency had met Paul Rackham Snr to discuss their findings but he had “expressed satisfaction”, saying the works were “a good job”.

Two charges against Mr Rackham Snr for damaging or destroying otter and water vole shelters had previously been dropped.

Judge Bacon said in its evidence the company had argued the work would improve the environment for water voles in the long term.

It had also carried out £400,000 remediation work including £220,000 for extra adjacent land to provide a floodplain.

She fined the company £17,000.

The court was told the Environment Agency and prosecutors are also seeking more than £63,000 in costs, an amount the defence described as excessive. The exact amount will be determined at a later hearing.