Communities across Scotland at risk from flooding reservoirs

More than 550 reservoirs around Scotland have been officially rated as “high risk” because of the homes, businesses, roads, railways and airports that could be flooded if they burst – and the dangers will increase with climate pollution.

Maps produced by the Scottish Environment Protection Agency (Sepa) reveal that parts of Edinburgh, Aberdeen, Inverness, Perth, Falkirk, Stirling and Fort William are vulnerable to reservoir floods. So are areas of Paisley, Milngavie, Hamilton, Greenock, Helensburgh and many other places.

Glasgow, Edinburgh and Prestwick airports are all in high flood risk areas, as are the M8, M9, M74, A9 and major railway lines. Murrayfield Stadium in Edinburgh, Scone Palace near Perth and much else are also at risk (see table below).

Experts point out that more rain and snow likely to be triggered by global warming could put additional pressure on dams, and heighten the chances of failure. But reservoir managers stress that dams are regularly inspected to keep people safe.

Under new legislation, Sepa is required to publish information on reservoir risks that were previously kept secret. Detailed maps on its website show all the areas which could be inundated if dams fail.

Data released to The Ferret discloses that 569 of the 670 reservoirs in Scotland have been assessed as high risk, with 49 medium risk, 49 low risk and three unclassified. The assessment is based on what could be flooded, not the actual likelihood of dams failing.

“We assess risk at sites across Scotland based on the maximum impact that a theoretical uncontrolled release of water could have on human health, transport links, critical infrastructure and conservation areas downstream of the site, not on the likelihood that a reservoir will fail,” said Sepa manager, Peter Pollard.

“The public can be assured that sites designated as medium or high risk require additional specific safeguards from operators, including regular inspection of the reservoir integrity by a qualified engineer.”

He added: “By implementing this safety regime, Sepa continues to ensure that each operator maintains their reservoir in a structurally sound and robust condition, so that the potential for an uncontrolled release is minimised under all likely weather conditions.”

Dr Richard Dixon, director of Friends of the Earth Scotland, argued that inspection and maintenance had to be absolutely thorough. “Climate change adds a new challenge, with more rainfall in general and heavier rain storms adding to the stresses that dams and banks have to cope with,” he said.

“Now we have a comprehensive picture of the reservoirs around Scotland, we need to make sure climate change is being built into future assessments and contingency plans.”

Alan Warren, vice chair of the British Dam Society representing engineers, urged people not to be alarmed. “No-one has died on account of dam failure in the UK since safety legislation was first introduced in 1930 although some near-miss incidents do occur from time to time,” he said.

“Climate change will potentially affect how our structures perform in the future…Global research work on climate change will help us to assess whether improvements to our dams are needed in the future to keep people safe.”

Professor David Crichton, a flood insurance specialist based in Scotland, urged that public liability insurance for dam owners be made compulsory. “This would be a cheap way for government to ensure regular safety inspections by independent experts, i.e. insurers,” he said.

Professor Chris Spray, a water expert from the University of Dundee, argued that legislation had enabled greater attention to be paid to a wide variety of reservoirs. “So you could even possibly argue that the knowledge and management has improved because Scotland’s reservoir safety has never been better understood,” he said.

Scottish Water is responsible for 261 reservoirs registered under the legislation. “The risk designation directs the level of statutory inspection required at each reservoir,” said a spokesman for the public sector company.

“Scottish Water has a duty to inspect and maintain these reservoirs. Supervising engineers visit and inspect them at least once per year and an independent engineer inspects every 10 years.”

He added: “The supervising and inspecting engineers will determine if any maintenance activities are required to manage the safety of the reservoir structures and Scottish Water will be given a prescribed duration to complete the work.”

The power company SSE is responsible for 77 reservoirs. “SSE has carefully managed all of its hydro generation assets,” said reservoir manager, Neil Lannen,

“Our dams and reservoirs are managed fully in accordance with the requirements of the Reservoir (Scotland) Act 2011 and the preceding Reservoirs Act 1975 (UK).”

High risk reservoirs

Places at riskReservoirsManagers
Glasgow airport, M8Balgray, Loch Thom, Elliston Weir and othersScottish Water
Paisley, Pollokshaws, Barrhead, M8, M77Balgray, Ryatt Linn, Waulkmill GlenScottish Water
Milngavie, A81, A807Mugdock, Kilmannan, CraigmaddieScottish Water
Helensburgh, A814, railwayHelensburgh reservoirScottish Water
Greenock, A770, railwayWhinhillScottish Water
Hamilton, M74DaerScottish Water
Edinburgh airport, M9, railwayCobbinshaw, Crosswood, Morton LowerScottish Canals, Scottish Water
Edinburgh Colinton, Prestonfield, A720, A7Clubbiedean, Torduff, BonalyScottish Water
Edinburgh Stenhouse, Gorgie, Balgreen and Murrayfield Stadium, A70, A71, A8, two railwaysHarperrig, HarlawCity of Edinburgh Council
Aberdeen, A93, A90Mannofield, SlopefieldScottish Water
Inverness, A9, A82, railwayLoch Dochfour, Quoich, Monar and othersSSE, Scottish Water
Perth, Scone Palace, A9, railwayLoch Tummel, Loch Rannoch, Loch Faskally and othersSSE, Scottish Water
Falkirk, Grangemouth, M9Carron ValleyScottish Water
Fort William, A82, A830Quoich, Loch Lochy, Loch Laggan and othersSSE, Alcan
Prestwick airport, A77RaithSouth Ayrshire Council
Troon, A78, railwayCollenanSouth Ayrshire Council
Callander, Bridge of Allan, Stirling, M9, A84, railwayLoch Katrine, Glen Finglas, Loch VenacherScottish Water
Livingston, A71, A 705CobbinshawScottish Canals
Carnoustie, A930Monikie South, DenfindAngus Council
Alloa, A907, railwayGartmornScottish Water
source: Scottish Environment Protection Agency

The spreadsheet released by the Scottish Environment Protection Agency listing all the reservoirs and their risk designations is available on The Ferret’s github page.

Photo thanks to David Baird, licensed for reuse under this Creative Commons Licence. A version of this story was published in the Sunday Herald on 17 December 2017.

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