Case study:Avon Barriers Project: Ferengair Weir

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Location: 55° 46' 4", -4° 1' 23"
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Project overview

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Status In progress
Project web site
Themes Fisheries, Habitat and biodiversity
Country Scotland
Main contact forename Alan
Main contact surname McCulloch
Main contact user ID User:Alan.McCulloch
Contact organisation SEPA
Contact organisation web site
Partner organisations Rivers and Fisheries Trusts of Scotland
Parent multi-site project

Case_study:Avon Barriers Project

This is a parent project
encompassing the following
Fernegair Weir

Project summary

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Fernegair Weir is one of two barriers on the Avon Water that are the focus of the Avon Barriers Project. This project is being undertaken in partnership between The Rivers & Fisheries Trust for Scotland, SEPA, South Lanarkshire Council and the Clyde River Foundation.

Ferniegair weir is approximately 60m wide. The crest has a lower section at the left bank (looking downstream). The majority of the crest is approximately 2.5m above the downstream bed level. The structure is skewed to the direction of flow at an angle of approximately 30 degrees.

Historical maps indicate that there has been a mill on this site since at least the mid-1700s, predating the railway viaduct and the A72 bridge. It is therefore likely that there has been some form of impoundment in the river at this general site for some time. OS Mapping from an 1858 survey indicates a “dam” present at the site of the current weir, and no railway viaduct at this time (see Figure 2-3). It is estimated that the present weir was built between 1880 and 1920.

No as-built drawings are available for the structure. Previous reports suggest that the construction of the weir is timber frame, which has since been encased with a concrete apron in the 1940’s. It is believed that this was built directly onto the bedrock which outcrops along much of the reach.

Feasibility & optioneering for improving fish passage across this structure has just been completed and the options are being assessed with a view to moving forward to design and build.

Monitoring surveys and results

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The RAFTS habitat scores highlight this weir and the upstream weir at Millheugh as the highest priority barriers in the Clyde catchment. Providing fish passage will open up significant areas (up to 35km) of excellent quality habitat to migratory salmonids.

Lessons learnt

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Catchment and subcatchment


River basin district South East
River basin New Forest


River name Avon Water
Area category 10 - 100 km²
Area (km2)
Maximum altitude category Less than 100 m
Maximum altitude (m) 82
82 m
0.082 km
8,200 cm
Dominant geology Calcareous
Ecoregion Great Britain
Dominant land cover Improved grassland
Waterbody ID GB107042011300

Other case studies in this subcatchment: Avon Barriers Project, HLS New Forest, Holmsley Inclosure Stream Restoration


Name Avon Water: Ferengair Weir
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WFD water body name
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Desired post project morphology
Heavily modified water body No
National/international site designation
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Protected species present No
Invasive species present No
Species of interest
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Project background

Reach length directly affected (m)
Project started 2015/01/01
Works started
Works completed
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Cost for project phases

Phase cost category cost exact (k€) Lead organisation Contact forename Contact surname
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Post-project management and maintenance

Reasons for river restoration

Mitigation of a pressure
Biology Obstruction to fish
Physico-chemical Poor WFD water body conditions
Other reasons for the project


Structural measures
Bank/bed modifications Weir modification
Floodplain / River corridor Improving fish migration
Planform / Channel pattern
Non-structural measures
Management interventions
Social measures (incl. engagement)


Hydromorphological quality elements

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Any other monitoring, e.g. social, economic

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Monitoring documents

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Supplementary Information

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