WILDLIFE campaigners claim a new report shows controversial plans for 500 homes on land next to Askham Bog would dry out the York nature reserve - and that the scheme should be scrapped.

The Yorkshire Wildlife Trust (YWT) says the report by development consultancy Mott MacDonald clearly indicates that Barwood Land’s scheme for land off Moor Lane would result in the drying out of Askham Bog, which the trust runs.

But the developers claim their plans “categorically cannot cause damage to the bog”.

YWT conservation officer Sara Robin said the report confirmed it would have a negative effect on a nationally important site and should be turned down by City of York Council.

“The developers said that a development would not affect the bog, as it relies on rainwater,” she said.

“They also said that the groundwater on the development site was not connected to the groundwater on the reserve and finally they said that changes in surface water - due to drainage of the site to keep the houses dry - would not affect the bog.

“The Mott Macdonald report disagrees and says that changes in the groundwater and surface water will affect the reserve.”

Mott MacDonald says in the report that it was appointed by the council to provide a peer review of the hydraulic, hydrologic and hydrogeologic information provided by the applicant in support of its planning application,"so as to inform the decision to be made by City of York Council planning committee".

The report raises a number of concerns over data quality, including: “Dismissal of bog hydrology as solely ‘dependent on rainwater’ is a substantial misrepresentation of the system."

It also said: "Basic hydrogeological analyses that would aid understanding, such as spatial plots of groundwater levels and hydrochemical parameters, are not presented."

But a spokesman for Barwood said they have had consultants produce a technical report that addresses the impact of the development on the land’s hydrology.

A letter in response to issues raised during the consultation on the application says: “The proposed development will not affect rainfall and therefore the proposals will not result in damage to the bog by virtue of changes in the quality or supply of surface water or ground water and will also not result in drying out.

“Given that the primary input into the bog is from rainfall, the proposed development categorically cannot cause damage to the bog as is alleged.”

Almost 7,000 people have objected to the housing plans, including naturalist and broadcaster Sir David Attenborough, who has said he is "so disappointed" that the proposal had been made for the "irreplaceable" bog.

The trust has claimed the bog is a "truly exceptional site for wildlife", which would be endangered by the development but Barwood has insisted it would would help to meet York’s acute housing needs and also assist in the long-term protection and enhancement of the bog, saying a series of technical studies had all demonstrated that the site was "entirely appropriate" for housing development.

Sara Robins, from the trust, said she had spoken to the council and it looks as if the planning application would not go to the planning committee until later in the summer, with no date set as yet.