Safety incidents at UK dams are going unreported, warn experts

Environment Agency demands mandatory disclosure as rain and budget cuts combine to raise alarm on reservoirs' integrity

Safety problems with Britain's ageing dams are going unreported, experts warn. Exceptionally wet weather combined with budget cuts are raising concerns about the integrity of some of the UK's water reservoirs. There have been at least 41 safety problems at dams in England and Wales over the past six years, including 14 serious incidents. However, dam experts say there is mounting evidence that not all major incidents are being disclosed, and the Environment Agency (EA), responsible for dam safety in England and Wales, wants reporting to be made mandatory.

The warning comes as it was revealed that almost 300 flood-defence schemes across England have gone unbuilt after government spending was slashed. As a result, thousands of homes have flooded as the deluge overwhelmed existing defences. Charles Tucker, of the National Flood Forum, said: "The fact is that flood-defence spending has decreased, while flooding has increased. Spending is clearly not enough."

The Independent on Sunday has learnt that safety checks are currently overdue at 51 large reservoirs and that the owners of 40 more sites have failed to meet official deadlines to carry out safety improvements. Hundreds of smaller dams are exempt from inspection.

The warning comes as large areas of the country remained on flood alert following continuing heavy rainfall. Thirteen flood warnings, issued by the EA, were in place yesterday evening Ω six in the Midlands, five in the Anglia region and two in the South-west. There were also 62 flood alerts across England and Wales. The Met Office issued an amber warning of rain across parts of England and Wales. Forecasters said most parts of the UK would remain "largely dry" today, with the exception of the west of Scotland, which can expect "quite a wet day". But more rain is on the way.

Experts say that while the probability of dam failure is low, ensuring reservoir safety is vitally important in Britain because of the number of dams that pose a "high hazard" by being located upstream of heavily populated areas. The consequences of failure are great and careful risk management is essential, they say. "The lack of knowledge of dam incidents can give rise to misplaced optimism with respect to the long-term deterioration of dams," the EA said.

It is estimated that most major British reservoirs are embankment dams, where the barrier is made of earth or rockfill which has been excavated, dumped and compacted. Their average age is more than 100 years, according to the British Dam Society. Most failures are linked to overtopping (overflowing) water during periods of extreme flooding, or internal erosion of the dam caused by pipe or hydraulic fracturing.

The last dam disaster in Britain was in 1925, when the failure of two dams near Llanwrst in north Wales led to the deaths of 16 villagers. The worst tragedy occurred after a dam failed at the Dale Dyke reservoir, near Sheffield, Yorkshire, in 1864, killing 244 people.

One of the most recent serious incidents, at Ulley, near Rotherham, South Yorkshire, in June 2007, resulted in 1,000 people being evacuated from their homes and the closure of the M1 motorway. The dam owner, Rotherham Metropolitan Borough Council, was served with an enforcement notice in 2010 over missed deadlines for safety improvements Ω the second time in four years. The council said it had asked for and was given extensions to carry out remedial work. "The revised deadline was fully met … No matters in the interest of safety were raised in the subsequent inspection," a council spokesman said.

A further 13 public bodies and companies owning dams have been threatened with legal action for failing to carry out safety measures. They include the National Trust, the Ministry of Defence, and Welsh Water.

Dr Andy Hughes, director of dam engineering at the consultancy Atkins and a visiting professor at Bristol University, said: "The general condition of dams is very good and the majority of owners have been responsible in keeping them up to modern standards. But there's always a residual risk – we have three or four major incidents or accidents a year, and it's important to remind dam owners about them. We have to be vigilant and ensure that engineers inspect reservoirs regularly."

An EA spokesman said: "Any non-compliance with the Reservoirs Act is a concern and while it is a small percentage of the total number of dams we regulate, we want no incidents at any reservoirs."