Improvements planned for Spey Dam

The British Aluminium Company constructed the Spey Dam in 1943 to allow water to be diverted into Loch Laggan for onward transfer to Fort William, where it was used (and continues to be used) to produce hydroelectricity for the company’s Lochaber aluminium smelter in Scoltand.

The Spey Dam is located at Crathie, a few miles west of Laggan, in Badenoch & Strathspey and the present operator is Rio Tinto Alcan. With an overall length of 287m and a maximum height of 17.4m, the dam has an embankment section, a 93m long spill weir, a fish pass and a fish counter to monitor movements of adult fish.

Reclassification

Classification of waterbody’s status (including access for fish migration) is a continuing annual process, which utilises all information available to the Scottish Environment Protection Agency (SEPA). When assessing fish migration, a range of issues are considered, including fish counter data and information on juvenile fish distributions and their abundance upstream of the obstacle. Where there is evidence that a structure presents a complete, or almost complete, barrier to migrating fish, SEPA includes this in our classification under the Water Framework Directive.

This process takes into account natural barriers to migrating fish, whereas dams and other structures will only require attention if they are preventing migrating fish reaching significant areas of habitat which fish would naturally have been able to access. The implications of a downgrade in status are that the fish passage issues need to be assessed in more detail and any potential additional mitigation options considered, and implemented where appropriate, before the waterbody can be reclassified as Good.

Spey Dam has always contained a fish pass but only recently has a fish counter been installed to monitor fish movements. Current information shows that fish are able to pass thorough the dam but the efficiency of their passage may be compromised and further investigations are ongoing with the operator as to how to improve this. Separately, fish monitoring in the water catchment area above the dam has shown a severe decline in juvenile salmon, with an almost complete absence of young-of-the-year juvenile fish in recent years. This suggests that the dam is almost a total barrier to fish migration.  

Whose responsibility?

Under the Water Framework Directive, it is an operator’s responsibility to provide a suitable passage for migrating fish. SEPA and Rio Tinto Alcan have been working closely to investigate the current operation of the Spey Dam fish pass to ensure that fish can pass freely across it. While it is too early at this stage to define what work might be undertaken, this partnership approach, which also includes other interested stakeholders, will allow us to identify and prioritise measures for improving fish spawning conditions throughout the upper River Spey catchment.

The waterbodies upstream of the Spey dam reservoir are presently classified as being of Poor Ecological Potential in respect of fish passage with an objective of achieving Good Ecological Potential by 2027.

Enhanced passage

SEPA has currently identified 238 weirs and dams, and 56 other man-made structures that are either preventing or restricting fish migration in Scotland’s river systems. Between 2015 and 2021, we aim to remove 145 of these barriers and restore access to 167 water bodies and two protected areas previously isolated from migrating fish. During the period 2021 to 2027, a further 149 barriers will be targeted, which will facilitate fish migration to 126 water bodies and one protected area.

To achieve these goals, SEPA will work directly with operators to ensure they take the actions needed to allow or enhance fish passage through historic weirs and dams, including the Rivers and Fisheries Trusts. Barrier removal can be achieved in several ways. Fish passes can be constructed over or around existing or, where possible and appropriate, barriers created by abandoned weirs and dams can be demolished.

More detailed information on this work can be found in “The River Basin Management Plan for the Scotland river basin district: 2015–2027” available on the website https://www.sepa.org.uk/