Reservoir safety checks more imperative than ever

Friday, 02 May 2025

With Scotland experiencing more frequent episodes of heavy rain, Forestry and Land Scotland (FLS) is continuing with its latest round of safety and integrity checks on the 16 reservoirs – often referred to as lochans - in its care.

For public safety, The Reservoirs (Scotland) Act 2011 requires that those holding more than 25,000 m3 of water or more – ten times the size of an Olympic swimming pool – are registered with governing body SEPA.

They must also be inspected regularly and where required, maintained and repaired in order to prevent potential breaches that would result in sudden uncontrolled surges and downstream flooding.

Of the 16 reservoirs co-owned or wholly managed by FLS, nine are smaller unregistered bodies of water but the remaining seven are all registered with SEPA.

FLS Civil Engineer, Alan Dickerson, who has the responsibility of supervising the reservoirs, said; 

“Most of the FLS reservoirs are created by earth embankment dams over 100 years old and each around 5m high and up to about 100m long with (mostly) side spillways. Overtopping and erosion are our biggest concerns but these structures have survived and served for a long time and with diligent care they will continue to do so.  

“Surveillance and monitoring is important, especially as we experience more extreme weather that could affect these earthworks. Our checks include measuring crest and water levels, clearing vegetation and channels and flow recording.

“Some reservoirs also have valves that release the water in an emergency as part of a planned response. These need to be regularly checked to make sure that they still function correctly.

“The only incident we have experienced was at Glencoe in 2023, when during the test, a boulder resting against the valve moved when the valve was opened, lodged underneath it and prevented the valve from being closed again. It was a freak accident that saw the water drained from the reservoir but the issue was resolved.”

All registered reservoirs are given a high, medium or low risk designation by SEPA according to the level of downstream inundation that would occur if there was a breach. 

Four of FLS’ registered reservoirs are high risk, two are medium risk and one is low risk. High risk reservoirs are periodically inspected and – together with the medium risk locations – are continuously monitored by a Scottish Government approved supervising engineer.

FLS also submits annual statements of compliance to SEPA for all of these and complies with any direction regarding their monitoring, maintenance and safety. 

David Cooper, SEPA Senior Manager - Water and Land Unit, said:

“SEPA welcomes Forestry and Land Scotland’s continued commitment to the safe management of its reservoirs. Protecting people and communities is at the heart of Scotland’s reservoir safety regime, and we work closely with reservoir managers to ensure that high standards are maintained.

“Responsible management includes a regular cycle of inspection, maintenance and repair, ensuring the highest standards of safety and resilience.”

In recent years works had to be carried out at two high risk reservoirs (Bruntis & Glencoe) to repair and improve spillway capacity for safe routing of floods and to increase freeboard (the distance from the normal water surface to the dam crest). Taking several years to design and construct, the overall cost – in the region of £500,000 – was around half the cost of deconstructing and removing the reservoirs altogether.

Alan added;

“These days the reservoirs are environmental havens and recreational spaces. Some of the more picturesque sites, such as at Glencoe in Lochaber and Kirroughtree in Galloway, are frequently used as backdrops for wedding photos . Perhaps the most visited one is the smaller reservoir near Pitlochry at the site of the annual Enchanted Forest experience.

“Regardless of where they are and what they are used for, it’s our job to make sure the larger reservoirs remain structurally sound.”

Notes to Editors

  1. FLS’ nine smaller reservoirs (10,000-25,000m3) are: Affordsk (Moray & Aberdeenshire); Dumore, Mharaich and Ranoch reservoirs (Tay); Kilmory, Na Gualine (West Argyll); Lime Hill (Cowal and Trossachs) Penningham, Bruntis Little (Galloway).
  2. FLS’ seven larger reservoirs (25,000m3 +) are: Loch an Torr, Lochan A’ Ghurrabain (West Argyll); Lochan A Ghleannain (Cowal & Trossachs); Glencoe Lochan (Lochaber); Loch Sheilah (Nth Highlands); Loch Horn (Tay); Bruntis Loch (Galloway)
  3. Some of FLS’ smaller reservoirs are thought to have been built in the early days of the Forestry Commission, possibly as job creation projects or to create habitats or fishing ponds. However, most of them ended up with the old Forestry Commission through estate purchase in lieu of death duties. Some of these will have been built for fishing, for use as a private water supply or for river water regulation. One reservoir (Bruntis Loch) was even used as a source of water for lead mining in the 1750s.
  4. Forestry and Land Scotland (FLS) manages forests and land owned by Scottish Ministers in a way that supports and enables economically sustainable forestry; conserves and enhances the environment; delivers benefits for people and nature; and supports Scottish Ministers in their stewardship of Scotland's national forests and land.
  5. Home - Forestry and Land Scotland | twitter.com/ForestryLS
  6. Media enquiries to Paul Munro, Senior Media Manager, Forestry and Land Scotland Media Office 07785 527590 or paul.munro@forestryandland.gov.scot