A councillor has urged the Government to make public which reservoirs are deemed a threat to human life if their dams are breached – as it is revealed that five in the Bradford district have been classified as “high risk”.

The Environment Agency (EA) has carried out a study of large reservoirs in England and Wales and drawn up maps for emergency planners to show the potential loss of life if a dam is breached during major flooding.

However, a spokesman for the EA told the Telegraph & Argus the Government Department for Food and Rural Affairs (Defra) and the security services will not make the information public, stating that revealing their locations would “adversely affect national security and public safety”.

Bradford Councillor Michael Ellis , the region’s representative on the Regional Food and Coastal Committee, said: “I am aware that a report has been presented that informs us there are five reservoirs in the Bradford area which are deemed to be high risk, with an additional one in Lancashire which if it breached would come in our direction.

“Defra has told us not to disclose anything about where they are.

“The likelihood of a breach is perhaps remote but we have had residents evacuated because of flooding recently. I think people have a right to know.”

The EA spokesman said reservoir flood maps are available online, but only show information about “large raised reservoirs” – those that hold more than 25,000 cubic metres of water – and do not give information about the risk to human life.

Detailed plans are only available to emergency planners “due to the sensitivity of the information,” the spokesman said.

Coun Ellis (Con, Bingley Rural) has also raised concerns over “orphan dams” on reservoirs which are often abandoned mill ponds whose locations and owners are often unknown.

He said: “My concern is that dams which have been abandoned by companies could cause flooding problems. They may only be 5,000 cubic metres, but that is 5,000 tons of water.

“I am more concerned about those than the major reservoirs which are inspected regularly because it may be that nobody owns them.

“It may be the companies have walked away and the mills have been pulled down but they are still there.”

The EA spokesman said: “We are unable to release details of which reservoirs in the Bradford district were on the list produced by Defra as it would adversely affect national security/public safety.

“This is also the view of Defra and the security services.”

Tony Poole, principal engineer for drainage at Bradford Council, said an emergency action plan had been formed to deal with any dam breaches.

He said: “We have got procedures in place if a dam breaches.”

Dafydd Williams, of Bradford-based Yorkshire Water , said: “While we do not comment on individual sites for security reasons, we can reassure people all our sites are regularly inspected by independent engineers and are compliant with the Reservoir Safety Act.”

The Environment Agency’s website says reservoirs in the UK have “an extremely good safety record” with no incidents resulting in the loss of life since 1925 – meaning reservoir flooding is “very unlikely to happen”.