Avon Barriers Project

RAFTS, in conjunction with the River Clyde Foundation and South Lanarkshire council, and funded by SEPA’s Water Environment Fund and the Clyde and Avon Valley Landscape Partnership, has undertaken a project to look at ways of improving fish passage on the Avon Water, a major tributary of the River Clyde in South Lanarkshire.

The Avon Water and its tributaries are currently downgraded under the EU Water Framework Directive (see here for more information), and the sole driver for this downgrade is the poor accessibility for migratory fish species as a result of in-river barriers. Part of Scotland’s industrial legacy includes weirs and other structures which were built to harness water for power. In many cases, the industry has long gone, but the weirs remain and many of them prevent species such as salmon from migrating upstream to areas where they would normally reproduce (or spawn).

At the height of Scotland’s industrial past, water quality and barriers to migration were such that species such as salmon declined to alarmingly low levels in catchments such as the Clyde. In recent times these fish species have rebounded dramatically in terms of numbers, and it is so heartening to see them throughout the system today. However, every effort needs to be made to support this recovery. Water quality is a big factor, but so is the amount of accessible habitat for spawning. The most effective method of increasing the amount of habitat available for spawning is to remove or ease in-river barriers to migration.

In the case of the Avon Water, two abandoned weirs have been identified as high impact obstacles to fish migration, and it has been calculated that almost 200km of spawning habitat is inaccessible because of these structures. Ferniegair weir is situated on the edge of Chatelherault Country Park, immediately downstream of an active railway viaduct. Millheugh weir is situated close to Larkhall, immediately downstream of a road bridge. Both weirs fall within South Lanarkshire Council boundaries.

Ferniegair Weir

Ferniegair Weir


Millheugh Weir

Work to date

In 2015 a ‘feasibility and optioneering’ study was carried out by Atkins Ltd to determine which options for enabling fish to migrate past the structures were both feasible (both in terms of practicality and cost), and which of the available options should be taken forward to design. A number of technical surveys were undertaken to inform this decision. A study such as this considers all possibilities, including:

  • Full or partial removal of the structure
  • A formal fish pass
  • An informal ‘easement’ of the structure
  • A bypass channel around the structure

In the case of both of the Avon Water weirs, removal was ruled out for a number of reasons. The remaining options were all considered in detail, and the preferred option has been identified as an informal ‘easement’ at each structure, consisting of  series of rock-type pools (in effect an informal fish pass). The full report can be read here.

Since this time, Atkins Ltd has been contracted to produce full designs for both ‘easements’, including buildability, early contractor involvement and any other surveys required to inform each design. Atkins Ltd are also contracted to supervise and oversee the work itself, which it is hoped will take place in summer 2016 (subject to consents, licenses and the agreement of structure owners).

Initial design work is now complete, and the outputs of this design work including reports, drawings and visualisations can be reviewed here.

Project stakeholders (structure owners, local authority, SEPA, River Clyde Foundation and others) have been involved during each phase, and have given their support to the work being undertaken.

Public Engagement

Public engagement is key to the success of this project. It is important that the local community are both aware of and supportive of the proposed work.

With this in mind, a public meeting was held on 8th March at Chatelherault Country Park. The meeting was widely advertised and well attended. A copy of the presentation given at the meeting can be viewed here.

If you would like to contact us to discuss any aspect of the project or with a question please use the following details:

Rivers & Fisheries Trusts of Scotland

Suite 1F40, 2 Commercial Street

Edinburgh, EH6 6JA

Tel: 0131 555 1158

Email: rob@rafts.org.uk

Thanks to our funders/partners:

WEF Logo SLC logo (2) SEPA



CRF logo Clyde & Avon Valley logo


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