F u n d e d b y

On behalf of

REPORT

Allan Water Barrier Easement Project Phase 1

Technical assessment of structures and identification of next steps

Client: River Forth Fisheries Trust

Reference: IEMPB4892R001D01 Revision: 02/Final Date: 12 April 2016

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Document title: Allan Water Barrier Easement Project Phase 1

Document short title: Allan Water Barrier Easement Project Phase 1 Reference: IEMPB4892R001D01 Revision: 02/Final Date: 12 April 2016 Project name: Allan Water Barrier Easement Project Phase 1 Project number: PB4892 Author(s): Clare Rodgers, Ian Dennis, James Davill and Alan Kettle-White

Drafted by: Clare Rodgers

Checked by: Ian Dennis

Date / initials: 12/04/16 IAD

Approved by: Ian Dennis

Date / initials: 12/04/16 IAD

Classification Open

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Table of Contents

1 Introduction 1 1.1 Background to report 1 1.2 Species impacted 1 1.3 WFD, ecology and hydro- and geomorphology justification 1 1.4 Aims and objectives 2

2 Task 1 Method 4 2.1 Site description 4 2.2 Structure assessment and surveys 6 2.3 Approach to determining options 9

3 Task 1 Results 11 3.1 Introduction 11 3.2 Danny Weir 11 3.3 Buttergask Weir 12 3.4 Lower Rhynds Dam 13 3.5 Millstone Weir 14 3.6 Greenloaning A9 Culverts 16 3.7 Feddal Abstraction 17 3.8 Feddal Dam 18 3.9 Wester Cambushinnie Dam 19 3.10 Auchinlay Culvert 20 3.11 Scouring Burn Sediment Retention Wall 21 3.12 Muckle Weir 23

4 Task 2 Method 25 4.1 Site locations and rationale for targeting the reach 25 4.2 Targeted walkover survey 25 4.3 Level of assessment used 25

5 Task 2 Results 27 5.1 Desk study of additional significant pressures 27 5.2 Targeted walkover survey 29 5.3 Review of salmon presence and habitat survey results 35

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6 Discussion: Catchment Plan 39 6.1 Catchment scale planning considerations 39 6.2 Catchment scale prioritisation 40 6.3 Prioritisation of Task 1 and Task 2 barriers 41 6.4 Factors limiting response to mitigation 46

7 Conclusions and Recommendations 48 8 Appendices (attached separately) 8.1 Appendix 1: Blank Task 1 Survey Sheet 8.2 Appendix 2: Completed Task 1 Survey Sheets 8.3 Appendix 3: Verification of Ownership Table for Task 1 8.4 Appendix 4: Blank Task 2 Survey Sheet 8.5 Appendix 5: Habitat data from RFFT and AWAIA 2016

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1 Introduction

1.1 Background to report The River Forth Fisheries Trust (RFFT) and the Alan Water Angling Improvement Association (AWAIA) are working together to address the issues caused by barriers, such as weirs, throughout the Allan Water catchment near Dunblane in Scotland. Based on SEPA data, ten of the barriers in this catchment may be eligible for WEF funding. These barriers are contributing to a downgrade in ecological status of the water body. The RFFT has added a further priority barrier (Muckle Weir) to this list due to its likely impact on fish migration.

Figure 1.1: Barriers range from weirs to reservoir outflows and culverts

The aim of this project is to assess these eleven barriers, consider the mitigation options available to restore fish passage at each and review the impact of additional features in the Allan Water catchment that might limit the effectiveness of mitigation measures for restoring fish passage in these rivers.

1.2 Species impacted The water bodies of the Allan Water catchment are failing to meet Scotland’s targets under the Water Framework Directive (WFD) of Good Ecological Status / Potential. One of the main areas in which the Allan Water water bodies are failing is in terms of the biological quality elements, specifically free movement of fish up and down the catchment. The passage of migratory fish including sea trout Salmo trutta and Atlantic salmon Salmo salar has been considered at each site through the course of this project. In addition to this, the passage of other native migratory fish species including resident brown trout Salmo trutta, European eel Anguilla anguilla and lamprey Petromyzonidae / Lampetra spp has also been given consideration, in line with the requirements of the WFD.

1.3 WFD, ecology and hydro- and geomorphology justification The mainstem Allan Water and its tributaries have a number of barriers along their length, associated with a range of uses and features including recreational fishing, road culverts and water supply. These barriers operate both individually and collectively at the catchment scale to inhibit the passage of migratory fish and prevent the transfer of sediments through the system.

SEPA has an obligation to deliver Good Ecological Status (or Potential) by 2027 in all Scottish water bodies including rivers, lakes, groundwaters and estuaries as part of the European Water Framework Directive (2000/60/EC) (WFD). The main water bodies in the Allan Water catchment as far downstream as Dunblane are:  Allan Water (Source to Greenloaning), water body ID 4601 – incorporating Danny Burn, Buttergask Burn and the Burn of Ogilvie.

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 Allan Water (Greenloaning to Dunblane), water body ID 6833 – incorporating Millstone Burn, Feddal Burn, Park Burn, Auchinlay Burn and Scouring Burn.  Orchill Burn, water body ID 4607 – incorporating Rhynd Burn.  Muckle Burn, water body ID 4604.  Lodge Burn, water body ID 4603.  Bullie Burn, water body ID 4605.  River Knaik, water body ID 4606.

Many of these water bodies are failing to meet the required classification, and barriers to fish passage are one of the main causes for this failure. SEPA has therefore identified a need for habitat improvements and removal of barriers or provision of mechanisms to enable fish migration for the water bodies in this catchment.

Eleven impassable barriers have been identified by SEPA and the RFFT in the Allan Water catchment and subsequently prioritised for mitigation through SEPA’s Water Environment Fund (WEF). This report provides RFFT with a technical assessment of these structures and others which are likely to be significant in this catchment, to determine the appropriate next steps to improve the passage of fish beyond the structures identified.

Whilst the focus of this work is on fish passage, this project recognises that the overall impact of these structures extends beyond fish migration. Measures to remove or mitigate these structures can bring a range of benefits to the health and resilience of the catchment as a whole through restoration of natural hydrological, geomorphological and ecological processes, and these factors have therefore also been considered in the identification of appropriate options for each site.

1.4 Aims and objectives The overall aim of this project for the RFFT is to facilitate fish passage for migratory species and increase habitat utilisation across the Allan Water catchment. The barriers have been considered both individually and also on a catchment scale, to ensure that the best options are proposed for each location and the catchment as a whole.

This project is the initial step in the design and implementation of measures to facilitate passage for all native migratory fish beyond current barriers and increase habitat utilisation across the Allan Water catchment. This report will therefore provide a sound basis for the next stages, such as detailed options appraisal, outline/ detailed design, and construction.

This report presents the findings of this independent expert-led technical assessment for Allan Water and recommends a key next steps for each of the eleven barriers (as well as other barriers which are identified as being significant) to support the next phase of work on the Allan Water Barrier Easement Project. This study builds on work undertaken to date by RFFT and the Allan Water Angling Improvement Association (AWAIA) to survey the habitat and monitor fish populations in the Allan Water catchment, and carry out initial discussions with landowners and other key stakeholders.

The bulk of this work (and hence this report) is broken by two main tasks: an assessment of the eleven individual structures already identified by the RFFT and SEPA (Task 1), and a catchment-scale appraisal, including surveys of additional structures and prioritisation of barrier easement works across the catchment (Task 2). Sections 2 and 3 present the method and findings (respectively) of the Task 1 structure assessment survey and desk study. Sections 4 and 5 set out the method and findings (respectively) of the Task 2 targeted walkover survey and desk study. A discussion, including a catchment

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scale plan and prioritisation of barriers for easement works is given is Section 6, followed by a summary of the main conclusions and recommendations in Section 7. Supporting documents are provided in the Appendices in Section 8.

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2 Task 1 Method

2.1 Site description The Allan Water catchment as a whole covers around 210km2 (CEH, 2016) and comprises of the mainstem River Allan and several tributaries (Figure 2.1). The river flows from the headwaters over 500m Above Ordnance Datum (AOD) in the northwest and southeast of the catchment towards the A9 trunk road which runs through the centre of the catchment, from where it flows southwest and then south parallel to the trunk road to join the River Forth near its tidal limit between the Bridge of Allan and Stirling. Land type in this upper catchment is predominantly grassland, heath and bog, while the lower part of the catchment along the mainstem Allan Water is dominated by livestock farming and improved grassland grazing, as well as built-up areas including Dunblane, Blackford and Greenloaning.

Eleven barriers on tributaries of the Allan Water are considered for Task 1, which have been identified as impassable to fish by SEPA and the RFFT. These barriers are listed in Table 2.1 and are shown in Figure 2.1.

Table 2.1 List of Task 1 barriers Location WFD water WFD water Barrier name WFD water body name (NGR) body ID body status

289292, Allan Water (Source to Danny Weir, Danny Burn 4601 Poor 708344 Greenloaning) Buttergask Weir, Buttergask 287492, Allan Water (Source to 4601 Poor Burn 708116 Greenloaning) Lower Rhynds Dam, Rhynd 285425, Orchill Burn 4607 Poor Burn 709593 283530, Allan Water (Greenloaning Millstone Weir, Millstone Burn 6833 Poor 707457 to Dunblane) Greenloaning A9 culverts, 283706, Allan Water (Greenloaning 6833 Poor Millstone Burn 707106 to Dunblane) Feddal Abstraction, Feddal 282682, Allan Water (Greenloaning 6833 Poor Burn 708597 to Dunblane) 282370, Allan Water (Greenloaning Feddal Dam, Feddal Burn 6833 Poor 708978 to Dunblane) Wester Cambushinnie Dam, 278745, Allan Water (Greenloaning 6833 Poor Park Burn 706729 to Dunblane) Auchinlay Culvert, Auchinlay 277784, Allan Water (Greenloaning 6833 Poor Burn 702303 to Dunblane) Sediment retention wall, 278011, Allan Water (Greenloaning 6833 Poor Scouring Burn 701735 to Dunblane) 281117, Muckle Weir, Muckle Burn Muckle Burn 4604 Good 707100

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Key: ± (! Task 1 Sites Rivers and Water Bodies

(! Lower Rhynds Dam

(! Feddal Dam

(! Feddal Abstraction Danny Weir (! (! Buttergask Weir

(! Millstone Weir Title (! Muckle Weir (! Greenloaning A9 Culverts Task 1 Sites Overview Wester Cambushinnie Dam (! Project Allan Water Barrier Easement Project Phase 1

Client River Forth Fisheries Trust

Date Scale

19/02/2016 1:60000

Figure

Figure 2.1

Drawn by Checked by Number

(! Auchinlay Culvert JP CR v1

(! Sediment Retention Wall

(! Dunblane

0 1,250 2,500 Meters © Crown Copyright and database rights 2015

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2.2 Structure assessment and surveys

2.2.1 Verification of ownership The structure assessment for each barrier was undertaken in several stages. Firstly, the individuals or organisations on RFFT’s list of presumed barrier owners were contacted in early January 2016 to make them aware of the project and confirm ownership of these structures and surrounding land. The extent to which structure ownership is known, and the initial views of owners from these discussions, was also used to inform the prioritisation exercise for Task 2 (see Section 6).

2.2.2 Structure surveys: site visit Surveys of the Task 1 sites were undertaken on 11th, 12th and 13th January 2016 to gain a sound understanding of each of these 11 barriers and their context within the catchment. A team of specialists in fisheries, engineering and geomorphology visited each of the 11 sites over the course of three days. A representative from the RFFT, joined the site visit intermittently to discuss the RFFT’s work in the catchment to date and the options for Task 2 sites (discussed in Section 5). A representative from the AWAIA also joined the team on one day to discuss the angling trust’s work in the catchment to date.

A standardised survey sheet was used to gather site information and focus discussion on the opportunities and constraints for barrier removal, modification or mitigation at each site (a copy is provided in Appendix 1). There were five main parts to the survey: 1. Detailed description of each structure. 2. Basic geomorphological analysis. 3. Rapid technical review of each barrier. 4. Appraisal of local constraints to restoration. 5. Assessment of the significance of low flows at each structure.

Photographs of each barrier and surrounding features of interest were taken at each site to support subsequent appraisal (these have been supplied as digital copies with the final report). The findings from the site survey formed the basis for the Task 1 Information Sheets.

It is noted that, due to the project delivery timescales, these surveys were undertaken in January when river flows were relatively high and daylight hours were limited. High river flows limited the visibility of some structures and impeded safe access all parts of each structure and the surrounding banks upstream and downstream to take measurements. Where direct measurements or observations could not be undertaken safely on the day of the survey, expert judgement was used instead by the team to undertake this assessment (using additional local information supplied by the Project Officer as required).

2.2.3 Structure surveys: desk-based assessment Designated sites To inform the appraisal of local constraints to restoration, a desk-based assessment was undertaken using freely available online sources (www.snh.gov.uk and www.magic.gov.uk; both accessed January 2016) to assess the proximity of each of the eleven barriers to designated sites (e.g. SSSIs, SACs or SPAs). This information was integrated in the “Main opportunities and constraints” section of the Task 1 Information Sheets (Section 2.2.4).

Utilities and infrastructure To inform the appraisal of local constraints to restoration, a rapid desk-based survey was undertaken using maps and aerial photographs to identify where utilities and infrastructure near existing structures

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may limit the feasibility and effectiveness of barrier easement solutions. This was based on the proximity of the river to assets such as roads, railways and pipe crossings. Observations made during the site surveys of eleven high priority structures for Task 1 also helped to inform this assessment, and the information was captured under the “Main opportunities and constraints” section of the Task 1 Information Sheets (Section 2.2.4).

Low flows To inform the assessment of the significance of low flows at each structure, desk-based calculations of low flow statistics were undertaken for each structure. The low flow conditions at each of the eleven sites was based on the gauged 95% exceedance (Q95) flow at the nearest National River Flow Archive (NFRA) gauging station, which is often downstream of the site. The Q95 flow data from the gauging station at Allan Water at Bridge of Allan (ID 18005) was used to estimate the Q95 for Auchinlay Culvert on Auchinlay Burn and the sediment retention wall on Scouring Burn. The Q95 flow data from the Allan Water at Kinbuck (ID 18001) was used to estimate the Q95 for the remaining nine sites.

The Q95 (in m3/s) for the gauging station is divided by the total gauged catchment area to provide a ‘Q95 ratio’. This ratio is multiplied by the catchment area of each site to obtain a scaled Q95 low flow condition for the eleven locations. The Flood Estimation Handbook (FEH) catchment descriptors for the eleven sites (in particular the standard average annual rainfall (SAAR), geology and elevation) were then compared against the catchment characteristics at the location of the gauging station (see Table 2.2 and 2.3). This comparative exercise was used to determine how representative the gauged Q95 flow data is for the eleven sites investigated within the catchment. Catchment characteristics of the eleven sites were considered to be sufficiently similar to those at the respective gauging station locations, and thus the method undertaken is considered to provide an appropriate high level review of the low flow conditions at these sites.

Low flow estimation is a modelling exercise based on catchment size and does not consider the influence of local conditions that may impound low flows (e.g. ponds and reservoirs) or increase flows (e.g. artificially straightened channels and culverts) on the flows experienced at each site. Direct monitoring (either continuous or spot flows) would be required to assess the impact of low flows at each site more fully.

Table 2.2: FEH catchment characteristics for gauging stations in the Allan Water catchment Catchment characteristics Area SAAR Elevation Geology Site (km2) (mm) (m AOD) Allen Water at Kinbuck 161 1384 93 Moderate permeability (fissured) Allan Water at Bridge of Allan 210 1335 11.2 Moderate permeability (fissured)

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Table 2.3: FEH catchment characteristics for each barrier Catchment characteristics Nearest Gauging station downstream characteristics SAAR Elevation Area Geology gauging sufficiently Site (km2) (mm) (m AOD) station similar to site? Danny Weir, 9.15 1521 100-150 Moderate Allen Water at Yes Danny Burn permeability Kinbuck (fissured) Buttergask 3.91 1341 100-150 Moderate Allen Water at Yes Weir, permeability Kinbuck Buttegask (fissured) Burn Lower Rhynds 10.2 1187 100-150 Moderate Allen Water at Yes Dam, Rhynds permeability Kinbuck Burn (fissured) Millstone 5.11 1380 100-150 Moderate Allen Water at Yes Weir, permeability Kinbuck Millstone Burn (fissured) Greenloaning 5.11 1380 100-150 Moderate Allen Water at Yes A9 culverts, permeability Kinbuck Millstone Burn (fissured) Feddal 3.62 1244 100-150 Moderate Allen Water at Yes Abstraction, permeability Kinbuck Feddal Burn (fissured) Feddal Dam, 2.31 1251 100-150 Moderate Allen Water at Yes Feddal Burn permeability Kinbuck (fissured) Wester 0.65 1235 100-150 Moderate Allen Water at Yes Cambushinnie permeability Kinbuck Dam, Park (fissured) Burn Muckle weir, 15.06 1447 100-150 Moderate Allen Water at Yes Muckle Burn permeability Kinbuck (fissured) Auchinlay 1.11 1102 60-100 Moderate Allan Water at Yes Culvert, permeability Bridge of Allan Auchinlay (fissured) Burn Sediment 6.21 1113 60-100 Moderate Allan Water at Yes retention wall, permeability Bridge of Allan Scouring Burn (fissured)

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2.2.4 Task 1 Information sheet for each structure Information gathered from the site survey (and supporting desk-based assessments) on the survey sheet (example provided in Appendix 1) was used to produce a non-technical information sheet for each of the eleven individual barriers on the Allan Water tributaries (given in full in Appendix 2). The structure of these sheets is based on the five main parts of the standardised survey sheet discussed in Section 2.2.3. This information was supported by the Task 2 review of habitat survey data (RFFT and AWAIA, 2016) and electrofishing data (RFFT, 2011 – 2015) as discussed in Section 4.

Once the preferred option for each site was identified, an approximate cost estimate was produced for delivery of the recommended next step at each site, based on the team’s previous experience in the costing of detailed options appraisal, design and construction of barrier easement projects. This was broken down to show costs relating to specific activities. Sites with simple solutions to fish passage issues were also identified where possible.

2.3 Approach to determining options One of the main aims of this project is to identify simple solutions to barriers and fish passage issues if there is one, and provide information as to what the next stage to achieving this should be (e.g. move to optioneering or progress to work) and how to go about it in order to address fish passage issues. The focus of this work was therefore on identifying the most affordable and practical solution in each case that is technically feasible and helps restore fish migration for the widest range of native migratory fish species. The range of options considered for each barrier is given in Table 2.4, noting that affordability and practicality are overriding concerns and may lead to options being recommended that would not necessarily restore the full range of natural ecological and geomorphological processes in that reach. The implications for fish passage of doing nothing at each barrier were also considered.

Table 2.4: Range of options considered for each barrier Option Description

A controlled intervention to completely remove a structure in the river. Where feasible this option can deliver the Full weir greatest geomorphological and ecological improvements removal removing the impoundment and allowing recovery of the natural flow and sediment regime.

Reducing the crest level across the whole weir or removing a portion or part of the structure by cutting a notch to ease Partial weir passage for fish and eel species. This is likely to removal moderately increase the water surface gradient upstream to allow sediment transport to take place.

Construct a new channel around the structure (or modify Bypass an existing mill lade). The nature, length, slope and channel geometry would be dependent on local conditions to the site and surrounding land use.

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Option Description Installation of structures on the weir structure itself or solutions leading up to the barrier to ease passage for fish. The most natural modification would be to construct a gently sloping rock ramp up to the weir crest. Other Modification measures might include installation of baffles or a of the weir technical (e.g. Larinier) fish pass on the face of the weir to improve passability. Different fish pass designs are appropriate depending on local site conditions and the target species.

The structure is left in its existing form. This option Do nothing includes consideration of the likelihood that the structure may degrade naturally, improving passability for fish.

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3 Task 1 Results

3.1 Introduction Full Task 1 information sheets for each of the eleven barriers identified have been provided separately to the RFFT and are given in Appendix 2. The key findings at each site are summarised below, in terms of verification of structure ownership, a list of recommended options to improve fish passage (ranked by preference together with rationale) and an approximate cost estimate and breakdown for the next stage of work to deliver the recommended option for that site. For confidentiality purposes, structure owner details are listed separately from the main report, in Appendix 3.

3.2 Danny Weir

3.2.1 Verification of ownership This structure is owned by the Tullibardine Distillery, located on the opposite side of the A9 downstream. The distillery owns and operates the abstraction for which the weir was built.

3.2.2 Recommended options and justification

Rank Option Description Replace the existing weir with a new structure that incorporates a single- 1 Technical fish pass flight Larinier (with eel pass) technical fish pass, to facilitate passage for salmonid fish species and eels at a wide range of flows. A rock ramp-style option could be considered as an alternative, however this would be significantly more expensive due to the extra length, 2 Rock ramp amount of construction material and water volume required by a rock ramp compared to a more traditional technical solution. Create a bypass channel using the relatively flat land on left hand bank. This would be in keeping with the local landscape and maintain the head of the weir. Due to the gradient and space available, the channel may need a Larinier or Denil type technical fish pass within it (or potentially a 3 Bypass channel rock ramp or series of steps and pools). This would also have to ensure that there is enough flow to maintain the abstraction water levels and provide enough flow depth in the bypass channel to facilitate fish passage.

Given that the site is likely to be actively managed by the distillery to maintain the abstraction, redesigning the weir to incorporate a technical fish pass is considered to be the most affordable and practical solution at this site. Full or partial removal at this site is not considered feasible as upstream water levels need to be maintained so that water can still be abstracted by the distillery. The abstraction is likely to limit flows over the weir during dry periods, which would inhibit the effectiveness of any modification or bypass option.

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3.2.3 Estimated costs for next step The next step for a technical fish pass solution is outline design of the technical fish pass, including topographical and ecological surveys, and flow modelling.

Approximate Activity cost estimate Topography survey £1.5k Protected species survey £1.5k* Hydraulic modelling to determine the design of the fish pass and abstraction £5k* (assumes flow/ level monitoring data are available for this reach from the distillery) New outline design including new fish screen for abstraction (including expert £6k fisheries input) TOTAL £14k *Costs marked with a star may be optional: protected species survey needed prior to construction, not necessary for outline design; hydraulic modelling not needed if already held by distillery for abstraction.

This will inform detailed design including CAR licence applications and planning permission (as needed). We also recommend discussing with the weir owner to identify if/ when there are plans to renew the structure, as this could be the best opportunity to incorporate a “fish friendly” design. We also recommend discussing with SEPA if/what the requirements of the CAR licence are for this structure, as that may provide an alternative driver for restoring fish passage at this site.

3.3 Buttergask Weir

3.3.1 Verification of ownership This structure is owned by Topfauld Farm on the right hand bank. Topfauld Farm (name and contact details provided in Appendix 3) owns this stretch of the river as far down as the A9. It is noted that according to the current owner (spoken with on site), this land will be changing hands in the next few months as the existing owners move away.

3.3.2 Recommended options and justification

Rank Option Description Fence off the left hand bank and allow the site to recover (and the bypass to develop further) naturally. This would need to include removal of the hardstanding Site 1 at the foot of the weir to increase the depth of water downstream. However this recovery may undermine the remaining structure. An alternative drinking water source for livestock may need to be identified. Formalise the natural bypass channel that is already there. This may be impaired Bypass 2 by the shallow water at the ford downstream, and the opportunity to remove the channel ford should also be considered as part of this option. Fully remove the weir structure and regrade the channel. Bank protection could be Weir 3 added if necessary to protect adjacent farm buildings/ roads. If needed, create a removal livestock drinking area at the ford using hardstanding to prevent further poaching.

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This barrier is located on a small stream in a relatively remote area. The most affordable and practical solution at this site is likely to be enhanced natural site recovery. Full removal would give the widest range of benefits in terms of restoring natural processes, but would be more complex and expensive to implement. Partial removal is unlikely to be worthwhile, and flows are unlikely to be sufficiently high to support a more technical fish pass or rock ramp solution.

3.3.3 Estimated costs for next step The next step for all solutions is discussion with the owner of Topfauld Farm (noting that this is likely to change soon) to identify plans for current and future use of this site, and willingness to consider the (relatively low cost) options identified above.

Approximate Activity cost estimate The work likely to be most cost effective to be carried out by the landowner themselves (with support from RFFT to advise on fisheries and geomorphological £5k aspects). TOTAL £5k

We also recommend exploration of available funding mechanisms that would help to encourage fish passage improvements at this site. The full benefits of improving fish passage at this site may not be fully realised if the fish passage at the A9 culvert downstream is not improved.

3.4 Lower Rhynds Dam

3.4.1 Verification of ownership This structure is owned by Blackford Estates. Carsebreck and Rhynd Lochs are managed by the estate as a bird sensitive area which is open for recreation (the dam falls within the Carsebreck and Rhynd Lochs SSSI and South Tayside Goose Roosts SPA).

3.4.2 Recommended options and justification

Rank Option Description Modify the existing structure to provide a range of depths and flows. It may be possible to focus water flow over the weir into a narrower channel to increase water depth and establish a technical fish pass with resting locations within the existing structure. More detailed structural Existing structure surveys are required to inform the type of technical fish pass that is most 1 modification and suitable here, for example single flight Larinier passes at the top and fish pass bottom with a naturalised channel providing flow variability between the two and a series of resting pools. The technical fish pass may need to extended beyond the base of the spillway to reduce the gradient and enable fish to access the pass easily. Add a large bypass channel around right hand bank. However, this 2 Bypass channel would require major earthworks in a protected area, and the effectiveness may be limited by relatively low flows out of the reservoir.

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Given the size of the existing spillway and its location in a nature reserve, there are no particularly affordable or practical solutions that can easily be implemented here. Modification to create a range and depths of flows within the structure (and extending the end into the pool below) is considered to be the most appropriate solution at this site. An additional bypass is possible, though the effectiveness is likely to be limited by low flows coming out of the reservoir, and significant earthworks would be required which may not be acceptable in a SSSI/ SPA. Full or partial removal at this site is not considered feasible as the dam is required to maintain the upstream reservoir (which is also a designated site).

3.4.3 Estimated costs for next step The next step for fish pass solution is detailed options appraisal and major survey work (including ecological, topographical and structural surveys) for the next phase of works here, if further fish passage work at this site is justified.

Approximate Activity cost estimate Topographic survey £2.5-£3k Continuous flow monitoring downstream (this may be cheaper if done by trust in £15k collaboration with local university) Flow modelling £5k Structural assessment of current spillway (visit by engineers and cores from £5k* structure) Protected species surveys (including breeding birds) £1.5k* Specialist birds survey may be required prior to modification works to the spillway, given the sensitive nature of this designated site. Our in-house £10-£30k* ornithologist has advised that this may cost £10-£30k to undertake depending on the level of detail, species and size of the site to be surveyed. An outline design £15k TOTAL £54-£74.5k *Costs marked with a star may be optional: structural assessment of current spillway not required if original design details are available from Blackford Estates; protected species survey needed prior to construction, not necessary for outline design; requirement for specialist birds surveys will be defined by Scottish Natural Heritage (it may be sufficient to stipulate that any works will be undertaken outside of sensitive periods for protected bird species), and all or some of this data may already be available through the Wildfowl and Wetlands Trust, Scottish Natural Heritage or other survey work undertaken by local ornithologists.

We also recommend discussing with SEPA the requirements of the CAR licence for this structure, as that may provide an alternative driver for improving fish passage at this site.

3.5 Millstone Weir

3.5.1 Verification of ownership This structure is owned by a neighbouring landowner (details in Appendix 3), who built the weir in around 2001 to supply water to an ornamental pond in the garden on the right hand bank downstream. The current owner (spoken with on site) noted that there is currently a lack of clarity with the Land Registry regarding whether their land boundary ends on the left hand bank (and including the river bed) or the right

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hand bank (and excludes the river bed). This would need to be resolved before any action is taken on the ground as the owner of the river bed would need to agree to any works undertaken on this weir.

3.5.2 Recommended options and justification

Rank Option Description Remove the top 1 m of the weir (and the scour pipes). Modify the remaining structure for fish access with a sloped notch in the remaining base weir to provide low flow access into deeper 1 Partial removal rest pool upstream (assisting passage of fish over the cascade). The offtake for the ornamental ponds could be modified from this, or an alternative source of water found. Fully remove this structure and reprofile the river bed (to enable fish to access cascading river sections upstream of the current pool). Reprofiling work may need to include replacing the existing bank protection downstream of the weir to protect 2 Full removal neighbouring houses and gardens. This option would need to include identifying an alternative water supply for the ornamental ponds (e.g. from the outflow pipe up on the right hand bank upstream of the weir).

Partial removal is recommended at this site as the most affordable and practical solution at this site as it represents a compromise between enabling passage for fish, limiting downstream flood risk and channel destabilisation, and maintaining the abstraction. Full removal would require significant profiling of the river bed to ensure that fish can still access the cascading river reach upstream of the current pond, and incurs greater potential flood risk to nearby homes and gardens.

3.5.3 Estimated costs for next step The next step for both solutions is development of outline design, including topographical and ecological surveys and flow/ sediment modelling.

Approximate Activity cost estimate Topographic survey £1.5-£2k Protected species survey/ Phase 1 £1.5k* Flow monitoring downstream to inform modelling for abstraction and flood risk (it £6k* may be cost effective if done by trust in collaboration with local university). Characterise upstream sediment - volume, grain size distribution, contamination £2k* risk Hydraulic and sediment modelling to determine downstream flood risk, £8k* geomorphological instability and options for abstraction An outline design (including expert fisheries input) £5k TOTAL £24-£24.5k

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*Costs marked with a star may be optional: protected species survey needed prior to construction, not necessary for outline design; hydraulic and sediment monitoring and modelling requirements are likely to be defined by SEPA and the local planning authority depending on likely or perceived risks to housing downstream.

This will inform detailed design including CAR licence applications and planning permission (as needed). We also recommend discussing with the weir owner if/ when there are plans to renew the structure, as this could be the best opportunity to incorporate a more “fish friendly” design. Furthermore, we suggest discussing with SEPA what the requirements of the CAR licence are for this structure, as that may provide an alternative driver for improving fish passage at this site.

3.6 Greenloaning A9 Culverts

3.6.1 Verification of ownership This structure is the responsibility of Transport Scotland and is managed by their “bridges and structures” department. It is noted that this also applies to the larger A9 culverts identified in Task 2 (Danny Burn, Burn of Ogilvie Burn and Buttergask Burn).

3.6.2 Recommended options and justification

Rank Option Description Modify the culverts structure by installing 0.3 m high baffles constructed within a low flow channel along one side of the large box culvert (providing a Culverts range of flows and resting places), across the concrete bed between the two 1 modification structures and along one of the two pipe culverts. Modify the second pipe (Option 1) culvert so it is only used at high flows. Repair/ replace gabion walls and replace the gabion mattresses immediately downstream with an alternative to provide adequate depth for fish to swim into the fish pass. Culverts Modify the culverts structure by installing features to provide varied flows and 2 modification resting places (e.g. bed roughening, baffles). This may not be sufficient to (Option 2) provide passage to all fish species along the full length of the structure

Modifying the existing culverts to incorporate a wider range of flows and resting places, and removing the degraded sections of gabion mattress, is considered to be the most affordable and practical solution at this site. Full or partial removal of these culverts is not considered practical as a route is required for the burn beneath these roads. A bypass channel is also not practical given the space restrictions associated with the overhead roads.

3.6.3 Estimated costs for next step The next step for both solutions is outline design, including topographical and ecological surveys and flow/ sediment modelling. Comprehensive flow modelling with and without the proposed option in place will be particularly important to inform discussions with the Asset Protection team at Transport Scotland.

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Approximate Activity cost estimate Channel survey (unless data available from Transport Scotland) £1.5k* Flow monitoring downstream. It may be cost effective if done by trust in £6k* collaboration with local university (unless data available from Transport Scotland) Hydraulic modelling to determine upstream and downstream flood risk to the £6k* road, and designs in terms of fish passage performance criteria Outline design £2k TOTAL £15.5k *Costs marked with a star may be optional: channel surveys and flow monitoring/ modelling not needed if already held by Transport Scotland for culvert.

This will inform detailed design including CAR licence applications and planning permission (as needed).

We recommend early engagement with the Asset Protection team at Transport Scotland to discuss their concerns and priorities for culvert management, and to identify potential opportunities for fish passage improvement based on their planned programme of repair and replacement works. It is noted that the downstream weir structure is likely to be a greater priority for barrier alleviation work.

3.7 Feddal Abstraction

3.7.1 Verification of ownership This structure is owned by a local landowner who has constructed the weir to maintain water levels for abstraction of water to the neighbouring fishing ponds. The land in this area is sometimes used for shooting parties, and a gamekeeper is employed by the landowner.

3.7.2 Recommended options and justification

Rank Option Description Retain the weir but modify the downstream conditions by removing the ford (adding a bridge over the top if access needed), deepening Downstream the pool and reinstating the river banks on either side. This would 1 condition need to be carefully designed to avoid the risk of undermining the modifications existing weir structure if the pool is deepened. A simple solution, but not necessarily effective for all fish species. As above, but build an additional structure to the front of the existing weir (either pre-barrages or a rock ramp) to improve access for a full range of species at a range of flows, while retaining the upstream 2 Additional structure water level. This is likely to be more effective than option 1, but potentially also more expensive. Pre-barrages or a rock ramp would be more visually sympathetic to the surroundings than a technical fish pass solution.

Given that a low cost solution is likely to be preferred for this relatively small structure, modifying downstream conditions by restoring the river channel and if necessary adding an additional structure to aid fish passage is considered to be the most affordable and practical solution at this site. Full or partial

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removal at this site is not considered feasible as upstream water levels need to be maintained so that water can still be abstracted for the fishing ponds. Flows are considered insufficient to support a bypass channel.

3.7.3 Estimated costs for next step The next step for both solutions is discussion with the weir owner regarding the importance of the ford at that location (and the weir structure for abstraction), to identify a scope for works that is likely to gain their approval. The best option for further consideration of options and engineering investigations is a (cheap and informal) on-site discussion with a local contractor.

Approximate Activity cost estimate The work is likely to be most cost effective to be carried out by the landowner themselves (with support from RFFT to advise of fisheries and geomorphological £8k-£15k aspects) TOTAL £8k-£15k

This is a potential site with a simple solution given that it is a small structure in a site where the river is already carefully managed (noting that the benefits of any solution will still be limited by additional structures a short distance upstream).

3.8 Feddal Dam

3.8.1 Verification of ownership This structure is owned by a local landowner who also owns the abstraction and associated fishing ponds downstream. The land in this area is sometimes used for shooting parties, and a gamekeeper is employed by the landowner.

3.8.2 Recommended options and justification

Rank Option Description Undertaken controlled, phased removal of the dam structure, recognising that the structure is already failing and any alternative would entail considerable 1 Dam removal repair works. This assumes that the dam is no longer used and this option is not limited by the potential impacts on the nearby Feddal Castle Listed Building. If the dam structure cannot be removed, redesign and repair the existing Dam redesign structure to improve the fish pass in line with current standards, especially at 2 and repair the base of the dam structure. This is likely to be the most cost effective option, though it may not be effective for the full range of native species. Install a large Larinier (with eel pass) technical fish pass from the overflow sluice on the left hand side. This is likely to take the form of at least three Technical fish 3 flights with resting pools. This option would be effective but expensive, and pass would require considerable engineering work including reinforcement and repair of the current structure.

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This structure is considered to be in poor condition, and any alternative to full removal is likely to entail considerable repair works. Carefully controlled, phased removal of this dam is therefore considered to be the most affordable and practical solution to the restoration of fish passage at this site.

3.8.3 Estimated costs for next step The next step for all solutions is discussion with the weir owner regarding the current use and importance of the dam structure, any planned repair works and whether there is scope for removal works that is likely to gain their approval.

This should be followed by outline design, including topographical, structural and ecological surveys and flow/ sediment modelling. Comprehensive flow and sediment modelling with and without the proposed option in place will be particularly important to inform discussions with the landowner and SEPA.

Approximate Activity cost estimate* Topographic survey £2.5-3k Continuous flow monitoring downstream (It may be cost effective if done by trust £15k in collaboration with local university). Characterise upstream sediment - volume, grain size distribution, contamination £3k risk Hydraulic and sediment modelling to determine downstream flood risk, £8k geomorphological instability and impact on fishing ponds downstream. Ecological surveys (protected species) £2k Structural assessment of current dam (visit by engineers and cores from £5k structure) - assumes original designs are not available An outline design for phased removal £10k TOTAL £45.5-£46k *Note that all costs are considered essential at this site given potentially highly significant risks downstream of removing this structure.

3.9 Wester Cambushinnie Dam

3.9.1 Verification of ownership This structure is owned by a local landowner (details given in Appendix 3).

3.9.2 Recommended options and justification

Rank Option Description Create a bypass channel from the right hand corner of dam (less steep), going under the adjacent road (using a bridge or culvert) with a 1 Bypass channel Larnier pass or similar in the steepest section (at the top end). This is likely to need to include a resting pool given the length and gradient.

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Modification of existing outflow, either by installing a multiple-flight Larinier (with eel pass) technical fish pass or extending and improving 2 Outflow modification the boulder ramp downstream to reduce the gradient, create a narrow low flow channel to increase water depth and provide resting points every 5 m.

A bypass channel from the right hand corner of the pond is considered to be the most affordable and practical solution at this site. Full or partial removal at this site is not considered feasible as the dam is required to maintain the upstream pond and removal would present a considerable risk to downstream roads and houses. Installation of a technical fish pass is possible, though it would not be in keeping with the rural area and would require regular maintenance.

3.9.3 Estimated costs for next step The next step for fish pass solutions is outline design, including topographical, structural and ecological surveys and flow modelling, if further work at this barrier can be justified.

Approximate Activity cost estimate Topographic survey £1.5 - £2k Flow monitoring downstream (it may be cost effective if done by trust in £6k* collaboration with local university). Flow modelling for downstream flood risk and to ensure there are sufficient flows £5k* to support a bypass channel Ecological surveys (protected species) £2k* Structural assessment of current dam (visit by engineers and cores from £5k* structure) Outline design for bypass channel incorporating technical fish pass (and bridge/ £15k culverts under road) TOTAL £34.5-£35k *Costs marked with a star may be optional: flood risk modelling requirements may be determined by SEPA/ local planning authority based on likely/ perceived flood risk downstream; protected species survey needed prior to construction, not necessary for outline design; structural assessment not needed if already held by the owner.

3.10 Auchinlay Culvert

3.10.1 Verification of ownership This structure is the responsibility of Transport Scotland and is managed by their Area Manager for this section of the A9. Note that this is a different contact compared to the Greenloaning A9 culverts and other Task 2 sites; Transport Scotland have advised that due to the smaller diameter, this culvert is considered to be a “drain” and is managed differently.

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3.10.2 Recommended options and justification

Rank Option Description Completely replace the structure with a larger culvert incorporating varied flows and resting places, designed to enable fish to navigate the 1 Culvert replacement steep gradient. This is only likely to be possible during major repair works to this section of the A9 road.

Most fish pass options are unfeasible at this site as the culvert is small and long, located deep beneath the road. Full replacement of the culvert with a larger structure incorporating areas of varied flow and resting places is therefore considered to be the most affordable and practical solution at this site. The small diameter and long length of the structure means it is not feasible to modify the existing structure (for example by adding baffles inside the existing culvert). Improving fish access to the downstream end of the culvert is unlikely to improve passage through this structure given the high velocities of flow through the culvert itself. Full or partial removal of the culvert is not considered practical as a route is required for the burn beneath the road.

3.10.3 Estimated costs for next step The next step for the culvert replacement solution is further survey work, including culvert surveys and flow modelling, if further work at this barrier can be justified.

Approximate Activity cost estimate Culvert survey (assuming data not available from Transport Scotland) £2.5k* Continuous flow monitoring upstream and downstream. It may be cost effective if done by trust in collaboration with local university (assuming data not available £15k* from Transport Scotland) Hydraulic modelling to determine upstream and downstream flood risk to A9 trunk road (to inform discussion with Transport Scotland), and inform designs in terms £3k* of fish passage performance criteria TOTAL £20.5k *Costs marked with a star may be optional: culvert survey, flow monitoring and modelling not needed if already held by Transport Scotland.

This will inform detailed options appraisal. We also recommend early engagement with the Asset Protection team at Transport Scotland to discuss their concerns and priorities for culvert management, and to identify potential opportunities for fish passage improvement based on their planned programme of repair and replacement works. If the survey/ modelling work listed above has already been carried out and is available from Transport Scotland, and Transport Scotland are happy to discuss options to replace this culvert, then works can progress straight to detailed options appraisal.

3.11 Scouring Burn Sediment Retention Wall

3.11.1 Verification of ownership This structure is owned by Network Rail and is the responsibility of the Route Asset Manager (Structures).

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3.11.2 Recommended options and justification

Rank Option Description Modify (or replace) the existing structure to incorporate a Larinier (with eel pass) type technical fish pass that passes through the structure, so that the gradient of the pass is reduced. Given the height of the structure, this may Technical fish 1 need to comprise two Larnier flights and a resting pool. This is likely to be pass best positioned on the right hand side of the retaining wall, rather than across the entire width of the structure. Additional engineering would be required to retain/ protect the wall on the left hand bank. Modifying the existing structure to incorporate a technical fish pass is considered to be the most affordable and practical solution at this site. Any engineering work in this reach is limited by space, both in terms of space in the channel between the retaining wall and the railway bridge (less than 6 m), and space along the steep banks for access. Full or partial removal at this site is not considered practical as it is assumed that the wall needs to be maintained to protect the downstream railway culvert. A bypass channel is also not feasible given the space restrictions associated with the railway line and steep river banks.

3.11.3 Estimated costs for next step The next step for this solution is outline design, including topographical, structural and ecological surveys and flow/ sediment modelling. Comprehensive flow and sediment modelling with and without the proposed option in place will be particularly important to inform discussions with the Asset Protection team at Network Rail.

Approximate Activity cost estimate Topographic survey £2-£2.5k* Protected species survey/ Phase 1 £1.5k* Continuous flow monitoring upstream and downstream (it may be more cost £15k* effective if done by trust in collaboration with local university). Characterise upstream sediment - volume, grain size characteristics, £2k* contamination risk Hydraulic and sediment modelling to determine downstream flood risk and likely changes in geomorphological processes (sediment transport and erosion risk to rail £8k* bridge culvert) An outline design (including expert fisheries input) £15k TOTAL £43.5-£44k *Costs marked with a star may be optional: protected species survey needed prior to construction, not necessary for outline design; topographic survey, flow monitoring and modelling not needed if already held by Network Rail; understanding upstream sediment characteristics would be beneficial but not essential given option is not to remove or lower structure.

This will inform detailed design including CAR licence applications and planning permission (as needed).

We recommend early engagement with the Asset Protection team at Network Rail to discuss their concerns and priorities for this structure, and to identify potential opportunities for fish passage improvement based on their planned programme of repair and replacement works. It may be worth

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discussion whether the wall is still working effectively, given that it appears to be bankfull of sediment upstream.

We also recommend investigation of historic channel development at this site (whether there was a natural fall/ barrier here prior to construction of the retaining wall and railway bridge) and what historic habitat utilisation upstream is likely to have been.

3.12 Muckle Weir

3.12.1 Verification of ownership This structure is owned by Loig Farm. It was initially understood that a utility runs underneath the rock ramp, however the landowner subsequently confirmed that there are no utilities under the weir structure (the nearest is a mains gas pipe under the road bridge upstream), and the ramp was built over 30 years ago as part of a series of measures to slow river flows and prevent flood risk. Sediment was dredged out of the channel and used to create embankments during the same period.

3.12.2 Recommended options and justification

Rank Option Description Modify the existing ramp, retaining the areas that fish already use and improving Ramp the rest (by adding and removing boulders and smaller stones to provide a 1 modification greater range of flows and depths, notching the weir lip and providing additional cover for the resting pool downstream). Fully or partially remove the weir. This would fully restore natural processes, however it is potentially an expensive option, with the risk of considerable head 2 Full removal cut threatening bank stability and potentially the road upstream. Alternative solutions to slow the flow in the river (e.g. large woody debris, channel meandering) should be considered as part of this option. Build a bypass channel on the left hand bank, where there is space for one if the Bypass 3 cost can be justified. This option would be expensive but natural looking and channel would fit with surrounding landscape. Install a Larinier or Denil (with eel pass) type technical fish pass on the current Technical structure to enable a wide range of species over the structure. However, the 4 fish pass appearance would not be in keeping with surrounding landscape, and it would need to be regularly maintained.

There is a range of options available at this relatively rural site depending on the concerns of the landowner for the flood risk reduction role of the rock ramp and fisheries assessment of its current functionality for fish passage. The most affordable, practical and simple solution at this site is to modify the existing structure to improve those specific sections of it that currently hinder fish passage. If the landowner is amendable and the risk to upstream banks and infrastructure is considered to be acceptable, then the rock ramp could also be fully removed.

3.12.3 Estimated costs for next step The next step for the Muckle Weir is further technical assessment to investigate how fish use the existing weir under a range of flows, to ensure any mitigation does not negatively affect features that work. This

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will include discussion with the local landowner to identify the current benefits of this structure (if any) from a flood risk perspective and how these can be improved.

Approximate Activity cost estimate Fish migration survey, using local fisheries specialists to observe how fish £2k navigate the current structure under a range of flow conditions Topographic survey of weir £1k-£1.5k* Flow monitoring downstream (it may be cost effective if done by RFFT and/or £6k* fisheries surveyors). Flow modelling to inform design £5k* Outline design (including specialist engineering and fisheries input) £5k-£10k TOTAL £19k-24.5k *Costs marked with a star may be optional: topographical survey, flow monitoring and modelling would be beneficial but not essential given option is not to remove or lower structure.

This is a potential site with a simple solution for modification and enhanced work once how fish currently ascent the structure is better understood, and provides the best solution if the structure need to be retained.

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4 Task 2 Method

4.1 Site locations and rationale for targeting the reach A high-level desk-based review was undertaken of additional pressures and issues in the Allan Water catchment beyond the sites already highlighted by SEPA, in order to identify additional barrier structures for the targeted walkover survey. This was supported by the review of key utilities and infrastructure in the catchment (see Section 2.2.3) and observations made in the field during the Task 1 structure surveys.

The additional pressures identified through this review were combined with the list of barriers already identified by the RFFT which were not on SEPA’s current database of impassable barriers. This list of sites was then discussed with the Project Officer to agree a shortlist of sites where significant fish passage issues have been identified and barrier easement work is particularly likely to be beneficial, for the targeted walkover survey for Task 2.

4.2 Targeted walkover survey A Task 2 site visit was undertaken on 14th January 2016 to gain a sound understanding of each of these six barriers and their context within the catchment. A team of specialists in fisheries and geomorphology visited each site over the course of one day. Given the short programme for this project, the Task 2 target walkover survey was undertaken the day after the Task 1 surveys to save on travel time. This had the added advantage of allowing some potential Task 2 sites where access was restricted on the day of survey to be visited earlier in the week. A further survey was undertaken by our fisheries specialist with representatives from the RFFT and AWAIA on Thursday 28th January 2016 to discuss fisheries and habitat aspects in more detail and revisit several of the high priority sites with the Project Officer to discuss constraints and opportunities in more detail.

A survey sheet was used to gather site information and focus discussion on the passability of each structure to fish and the opportunities and constraints for barrier removal, modification or mitigation at each site (a copy is provided in Appendix 4). Supporting photographs were taken at each site and digital copies have been provided with the final report.

4.3 Level of assessment used The findings from the Task 2 targeted walkover survey have been presented as succinct write-up of the notes for each additional site in Section 5.2, supported by relevant photographs, clearly stating the team’s expert opinion on the fish passage issues, recommended options and next steps at each site. This note also discusses the benefits of tackling these additional catchment pressures in terms of the improved effectiveness of the barrier easement works already considered for Task 1 for restoring fish passage processes.

At this stage the assessment of Task 2 sites was focussed on the justification to SEPA of including these additional sites in the plan of works for the catchment going forward. The assessment was therefore undertaken at a lower level of detail than for the Task 1 sites, and did not include verification of ownership, specific engineering input or geomorphological surveys, or estimated costs for next steps.

Habitat survey data (RFFT and AWAIA, 2016; see Appendix 5) and electrofishing data (RFFT, 2011 – 2015) were reviewed to understand the quality and quantity of available upstream habitat for each barrier and the extent to which each structure is a full or partial barrier to migration for a range of fish species. This information was fed back into the information sheets for Task 1 sites (Appendix 2) and Task 2 sites (Section 5.2).

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These combined findings were used to identify high priority areas of the catchment for barrier easement works (for example, areas where it appears a barrier is completely preventing the nearby fish population from accessing a large area of good quality habitat available upstream). This was used to develop a catchment-scale plan of where to target effort on fish passage and geomorphological improvement work in the Allan Water catchment.

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5 Task 2 Results

5.1 Desk study of additional significant pressures Findings from desk study including review of utilities and infrastructure were used to identify additional sites that are likely to act as a barrier to fish migration in the Allan Water catchment. The six barriers identified by the RFFT which were not on SEPA’s current database of impassable barriers (and not already covered by Task 1) provided an important starting point for likely barriers based on local knowledge of the catchment.

Given the relatively rural nature of the catchment and the nature of the barriers already identified by SEPA and the RFFT, it is likely that the main pressures on fish passage in the catchment from a utilities and infrastructure perspective are the A9 trunk road that runs parallel with the mainstem Allan Water to the south, as well as the railway line, and the network of minor roads.

In the field, a range of additional barriers were identified which were considered likely to significantly affect the benefit of any barrier easement works at Task 1 sites upstream or downstream. In practice, therefore, a long list of around ten potential Task 2 sites were visited in the field, and this list was refined down to those sites of highest priority once the structures had been surveyed.

The following six sites were identified as being the highest priority for action from the additional barriers not already covered by Task 1:  Feddal Burn: rock ramp (between two Task 1 sites).  Danny Burn: A9 culvert and sediment retaining wall (downstream of Task 1 site).  Burn of Ogilvie: A9 culvert (neighbouring tributary to Danny Burn).  Buttergask Burn: A9 culverts (downstream of Task 1 site).  Upper Rhynds Dam (upstream of Task 1 site).  Ashfield Weir (downstream of most Task 1 sites on the mainstem Allan Water).

These six Task 2 sites are shown on Figure 5.1. The findings and recommendations for each site are given in Section 5.2.

The main change from the original list of potential Task 2 sites identified by RFFT is the addition of the rock ramp on Feddal Burn and the removal of the series of man-made ponds on Park Burn. The Park Burn sites were removed from the list because there were considered to be such a large number of obstacles to be addressed (at high cost, given the proximity to nearby housing) for a relatively small benefit in terms of upstream habitat availability that work on this reach was unlikely to be simple or cost effective. By contrast, the Feddal Burn rock ramp was considered to be a barrier to fish migration but required relatively little extra work to improve passage for fish, thus significantly enhancing the benefit of any works at the Feddal Dam upstream and the Feddal abstraction downstream (see Figure 5.1).

Figure 5.2 Example of fish pass obstacle on the series of ponds downstream of Park Burn

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Key: ± (! Task 2 Sites (! Task 1 Sites Rivers and Water Bodies

Upper Rhynds Dam (! (! (! Buttergask Burn Danny Burn A9 Culverts A9 Culverts and Sediment Retaining Wall (!(! (! (! (! Feddal Burn (! Rock Ramp (! Burn of Ogilvie Title A9 Culvert Task 2 Sites Overview (! (! (! Project (! Allan Water Barrier Easement Project Phase 1

Client River Forth Fisheries Trust

Date Scale

26/02/2016 1:60000

Figure

Figure 5.1 Ashfield Wi(!er Drawn by Checked by Number

JP CR v2

(! (!

Dunb(! lane 0 1,250 2,500 Meters © Crown Copyright and database rights 2015

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5.2 Targeted walkover survey

Danny Burn A9 culverts and sediment retaining wall Location: 289335,708475 Water body: Allan Water (Source to Nearby Task 1 sites: Danny Weir (upstream) Greenloaning) 4601 Site description Brief description of structure This barrier comprises of a series of obstacles downstream of the distillery abstraction weir on Danny Burn: a small sediment retaining wall, an A9 culvert and another minor road culvert. The sediment retaining wall is a small weir consisting of a degrading gabion basket mattress (approximately 2 m wide, 3 m long and 0.4 to 0.5 m high), presumably constructed to protect the downstream culvert. From the retaining wall to the culvert, the channel walls and bed are reinforced with gabion baskets which have degraded leaving exposed mesh in the channel. The culvert base consists of a smooth concrete base (approximately 2 m wide by 90 m long) with a low-to-moderate gradient which runs beneath two roads. At the downstream end of the culvert there are four baffles (approximately lower 20 % of culvert length) with 0.3 m jump required over the first baffle and a 0.5 m depth of water downstream of baffles. Views on impassability to fish The fish data available (RFFT, 2015) suggest that the sediment retaining wall and downstream culverts contribute to a significant decrease in the fish densities found upstream of this section of river (from 0.47 to 0.08 salmon/m2, and 1.28 to 0.43 trout/m2). The whole section provides no resting areas for fish and the degrading gabion baskets and mattress present a fish welfare hazard that is likely to worsen as the condition of the baskets deteriorates. The shallow depth of water downstream (0.2 m) and over (0.1 m) the retaining wall are likely to be a partial barrier to salmon and trout. The fish data suggest that the culverted reach is a partial barrier to salmon and trout (< 50 % of density upstream compared to upstream) and full barrier to stone loach (present downstream) despite similar habitat type and condition. The shallow depth of the water (less than 0.1 m) in the upper 80 % of the culvert and high flow rate (no baffles) are also likely to be significant barriers for fish. Brief review of options

Recommended option: Extensively modify this reach and improve fish passage along the bed. Remove the retaining wall obstacle if possible or alternatively replace the degraded gabion basket structure with a formal concrete notched weir with sufficient depth downstream for resting fish in a range of flows. Remove the gabion baskets as far as possible, particularly from the bed were they are beginning to degrade. Modify the culverted section to increase water depth and provide frequent resting locations with low velocity flows for fish of up to 1 m length. This may be achieved with 0.3 m high baffles constructed within a low flow channel. A pre-barrage may also be required downstream of the culvert to improve access and provide deeper water resting points (with instream or overhead cover). The main constraints at this site are the culvert structures.

The next step at this site is outline design, including a topographic channel survey and flow monitoring/ modelling to assess flood risk implications of potential easement options. We also recommend early engagement with the Asset Protection team at Transport Scotland to discuss their plans, concerns and priorities for culvert management in this area.

Wider benefits Improving fish passage at this structure would improve access to the Danny Weir Task 1 site upstream. It is noted that the river channel between these sites also comprises of gabion mattresses and baskets which present a physical hazard to fish and prevent the habitat being utilised for spawning.

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Burn of Ogilvie A9 culvert Location: 289043,708445 Water body: Allan Water (Source to Nearby Task 1 sites: none on Burn of Greenloaning) 4601 Ogilvie Site description Brief description of structure This barrier is a large culvert under the A9, close to the culvert for Danny Burn. The base consists of a smooth concrete base (approx. 3 m width by 70 m length) with a low-to-moderate gradient. At the downstream end of the culvert there are low (0.1m high) steel baffles (approximately lower 20% of culvert length) set in a chevron pattern, originally designed to improve passage for fish. There is also a 0.3 m jump required into the first baffle with a 0.5 m depth of water downstream of the baffles.

Views on impassability to fish The shallow depth of the water (less than 0.1 m) in upper 80 % of the culvert and high flow rate (no baffles) are likely to be significant barriers for fish. The current “fish pass” baffles in this culvert are not compliant with current standards and are unlikely to be fit for purpose for the full range of native migratory species, particularly during low flows.

The fish data available (RFFT, 2015) indicate that the A9 culvert stream crossing is a partial barrier to salmonid fish and may be a full barrier when the optimal flow conditions do not occur (densities decrease from 0.32 to 0.23 salmon/m2, and from 0.76 to 0.53 trout/m2). There is a relatively large area (0.48 ha) of good mixed habitat suited to salmonid fish recruitment upstream of the culvert and is therefore a high priority for fish and fisheries interests.

Brief review of options

Recommended option: Remove the existing “fish pass” baffles and modify the culvert to increase water depth with 0.3 m high baffles constructed within a low flow channel. Provide frequent resting locations with low velocity flows for fish up to 1m length. A pre-barrage may also be required downstream of the culvert to improve access and provide deeper water resting point (with instream or overhead cover). The main constraints to work at this site are the size of the structure and overhead A9 trunk road, and limited site access for machinery.

The next step at this site is outline design, including a topographic channel survey and flow monitoring and modelling to assess flood risk implications of potential easement options. We also recommend early engagement with the Asset Protection team at Transport Scotland to discuss their plans, concerns and priorities for culvert management in this area.

Wider benefits Improving fish passage at this structure would improve access to and utilisation of the rest of the Burn of Ogilvie (an estimated 4800m2 of habitat) upstream. It is noted that there are no Task 1 barriers on this tributary, which may increase the benefits of undertaking fish passage improvements at this site.

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Buttergask Burn A9 culverts Location: 287720,708555 Water body: Allan Water (Source to Nearby Task 1 sites: Buttergask Weir Greenloaning) 4601 (upstream) Site description Brief description of structure This barrier is a large culvert under the A9, downstream of Buttergask Weir. The base of the culvert consists of smooth concrete (approximately 2 m wide by 40 m long) with a bend. There are baffles at the lower end of the culvert. At the upstream end of the culvert, the water depth is shallow (<0.1 m) with a high velocity.

At the downstream end of the culvert there is a set of two steps of approximately 0.5 m height. The lower step is constructed with gabion baskets (over a length of 0.4 m and are in reasonable condition) with 0.5 m water depth below. The second step is a 2 m long sloping concrete slab which forms the base of the culvert with shallow fast flowing water; this forms a significant obstacle to fish entering the culvert. This is exacerbated by a watergate which sits on the base of the culvert and has no sufficiently large gaps to allow larger fish to pass.

Views on impassability to fish Fish data (RFFT, 2012 and 2015) indicate that the culvert is a full barrier to salmon migration, but is a partial obstacle to trout (no other species were found downstream; note RFFT data do not distinguish between brown and sea trout).

Brief review of options

Recommended option: Modify the culvert to increase water depth using 0.3 m high baffles constructed within a low flow channel (removing or modifying the existing baffles), and provide frequent resting locations for fish with low velocity flows up to 1 m length. Improve access into the culvert by increasing the length of the steps and raising them in height, as well as replacing / modifying the water gate to prevent it being a barrier to fish movement. A pre-barrage may also be required downstream of the culvert to improve access and provide deeper water resting point (with instream or overhead cover). An alternative approach to improving access to the culvert would be to install and technical “pool and traverse” style fish pass at the downstream end with a new retaining wall. The main constraints to work at this site are the size of the structure and overhead A9 trunk road, limited site access for machinery and potential water quality issues from the drain on the downstream right hand bank.

The next step at this site is outline design, including a topographic channel survey and flow monitoring and modelling to assess flood risk implications of potential easement options. We also recommend early engagement with the Asset Protection team at Transport Scotland to discuss their plans, concerns and priorities for culvert management in this area.

Wider benefits Improving fish passage at this structure would improve access to the Buttergask Weir Task 1 site upstream. Compared to some of the other A9 culvert sites, this one is relatively small (below main trunk road only, no other minor roads) which provides a good opportunity for improvement. It is noted that diffuse pollution (fine sediments in the stream bed) impairs the condition of the habitat upstream.

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Upper Rhynds Reservoir Location: 285998,709881 Water body: Orchill Burn 4607 Nearby Task 1 sites: Lower Rhynds Dam (downstream) Site description Brief description of structure This barrier is a spillway from a reservoir upstream of the spillway from Lower Rhynds Dam on Rhynds Burn. The spillway consists of a smooth concrete base (approximately 2 m wide by 40 m long) with moderate-to-high gradient and head difference of 2 – 3m, but unlike the lower weir has no steps. There is high velocity shallow water flow (< 0.1 m) across the spillway.

Views on impassability to fish Fish data (RFFT, 2015) suggest that the lower weir is a full barrier to salmon and trout. The similar design of the upper weir suggests that this is also a full barrier to fish migration and therefore the restoration of fish passage is required at both weirs if fish are to be able to reach a small area of fish habitat in two tributary streams (recorded as 0m in RFFT and AWAIA habitat survey, so not likely to be significant). It is noted that these two tributary streams that flow into Upper Rhynds Reservoir appears to have a limited amount of habitat suitable for recruitment of trout. The stream channels appear to be modified (straightened) and fine sediments may impair the condition of the habitat. Brief review of options and justify:

Recommended option: Modify the existing structure to provide a range of depths and flows, similar to the recommendation made for the downstream spillway. It may be possible to focus water flow over the reservoir outflow into a narrower channel to increase water depth and establish a technical fish pass with resting locations within the existing structure. More detailed structural surveys are required to inform the type of technical fish pass that is most suitable here, for example single flight Larinier passes at the top and bottom with a naturalised channel providing flow variability between the two and a series of resting pools. There is sufficient depth of water and cover for fish downstream and upstream of the obstacle. An alternative option would be to construct a bypass channel, though this would require major earthworks in a protected area and the effectiveness may be limited by relatively low flows out of the reservoir. The large dam structure itself is the main constraint at this site, in addition to which it is located within a designated site (Carsebreck and Rhynd Lochs SSSI and South Tayside Goose Roosts SPA). Potential disturbance to protected species is likely to be a key deciding factor for fish passage improvement opportunities at this site.

The next step at this site (if work to improve fish passage here can be justified) would be detailed options appraisal and major survey work (including ecological, topographical and structural surveys) for the next phase of works here.

Wider benefits Improving fish passage at this structure would improve the benefits of fish passage improvement works to the Lower Rhynds Dam Task 1 site downstream. Restoration of fish passage is required at both outflows if fish are to be able to reach a small area of fish habitat in two tributary streams. However, it is noted that these streams are small and of poor quality for spawning, indicating that this site is likely to be a low priority for fish and fisheries improvements.

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Feddal Burn rock ramp Location: 282672,708574 Water body: Allan Water Nearby Task 1 sites: Feddal dam (upstream) (Greenloaning to Dunblane) 6833 and Feddal abstraction (downstream) Site details Brief description of structure This barrier is a large curved artificial rock ramp at the outflow of a second online pond on Feddal Burn (the pond acts as a sediment trap and has no second outflow / bypass channel). The dam impounds water in the pond for 125 m upstream. The rock ramp channel bed and walls are composed of large boulders set in a concrete base. The ramp is approximately 20 m long, 3-4 m wide and has a head difference of approximately 3 m. A rounded concrete beam, 0.3 m wide, forms an artificial lip at the top of the ramp.

Whilst originally designed to enable fish passage when constructed, the structure has now eroded at the downstream end so gradient is steep. There is significant erosion on the outside of the bend as seen by the slips in the adjacent hill side and the artificial bank protect that has been put in place to reduce this.

Views on impassability to fish There is a shallow depth of water (< 0.05 m) across the ramp at moderate flow and is therefore likely to be a full barrier to salmon and partial barrier to trout in all but exceptionally high flows. The Feddal Burn in general is a moderate-to- high gradient section of stream habitat with some areas of suitable gravel habitat for recruitment of salmonid fish between and upstream of the series of in-line ponds upstream of this weir. Salmon and trout are present downstream and moderate densities of trout fry are found upstream of the weir (RFFT, 2015). There is a large pond upstream of this weir which may act as a further barrier to fish migration before fish reach Feddal Dam. This upper pond has filled with fine and course sediment and the stream habitat downstream appears to be starved of coarse substrate, which impairs the condition of the habitat for fish.

Brief review of options

Recommended option: Extend (and repair) the rock ramp at the downstream end to reduce the gradient. Increase the depth of water around the inside bend of the fish pass to provide a channel of sufficient depth during low flows for fish passage, and create a resting pool halfway up the ramp. An alternative option would be to construct a bypass channel, though this is likely to be prohibitively expensive (and unpopular with the landowner) compared to modification of existing structure. The main constraints to work at this site are limited benefits (in terms of upstream habitat availability), the size of the structure, limited access for machinery, and potential changes to flow and sediment inputs / contamination of the fish ponds downstream which are managed for recreational fishing.

The next step at this site would be a structural assessment of the outflow and if / how it is used by fish during migratory periods.

Wider benefits Improving fish passage at this structure would improve access to the Feddal Dam Task 1 site upstream. It is noted that the river channel between the two sites appears to be starved of substrates which impairs the condition of the habitat for fish.

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Ashfield Weir Location: 278304,703869 Water body: Allan Water Nearby Task 1 sites: none on (Greenloaning to Dunblane) 6833 mainstem Allan Water

Site details Brief description of structure This barrier is a large weir at Ashfield, on the mainstem Allan Water. The weir is formed by a 2 m high, 35 m wide vertical wall associated with a historic mill which has been restored to incorporate a hydroelectric generation scheme.

Views on impassability to fish There is an existing fish pass on the right bank of the structure, which at moderate-to-high flow condition (January 2016) appears to have a high level of turbulence. At the high flows present during the site visit, the fish pass appeared to be flooded out and is not working effectively, in addition to which the structure appears to have degraded over time. While it was not possible to view the downstream entrance of the fish pass, it does not appear to reach the bedrock pool below. Improvement or replacement of the pass is therefore required to meet current guidelines.

The weir is located at the head of a long (100 m or more) set of natural bedrock cascades and waterfall obstacles. Water flow in the upper half of the natural obstacle is also likely to be affected by water abstraction for the hydroelectric generation scheme.

Brief review of options

Recommended option: Modify the existing weir to maintain an effective flow of water through the pass that optimises the period of time when the pass is usable by fish and increase the length of the pass so that it may be accessed from the pool downstream. This could take the form of replacing the existing pass with a dual flight Larinier (with eel pass) technical pass with a rest location along the right hand bank (ca. 20-30 m long) which would help to meet current guidelines. It is also necessary to establish if the natural waterfalls downstream of the fish pass form a significant obstacle when water is being abstracted by the hydroelectric scheme. The main constraints to work at this site are limited access for machinery on the right hand bank (noting that this has not inhibited previous fish passage work at this site).

The next step at this site would be outline design, including flow monitoring and modelling, and topographic and structural surveys of the current weir and fish pass (under low flow conditions). Comprehensive flow modelling will be particularly important to inform fish passage conditions over the natural obstacles downstream and consider how this can best be addressed, either by potential low cost modifications to the bed, or additional licencing restrictions to the abstraction.

Wider benefits Improving fish passage at this site for the full range of species and sizes of native migratory fish is a high priority for fish and fisheries, to maximise fish health and numbers in the wider Allan Water catchment. Given the weir is located in the lower part of the catchment, the potentially significant expenditure of energy and delays in migration at this site have implications for the migration of fish into the rest of the catchment and their ability to ascend other obstacles assessed by this study.

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5.3 Review of salmon presence and habitat survey results

5.3.1 Introduction The Allan Water is a major spate fed tributary of the lower River Forth. The main channel of the Allan Water flows over some 33.6km and has a number of significant tributary streams which are utilised for recruitment of migratory salmonid fish which is defined as an associated protected area for fish.

Habitat survey data (RFFT and AWAIA, 2016; see Appendix 5) and electrofishing data (RFFT, 2011 – 2015) have identified juvenile Atlantic salmon and brown trout (including sea trout) to be relatively widespread, while European eels, lamprey, stickleback, stone loach and European minnow had very limited distribution in some tributaries. Habitat details such as river width length and natural limits to migration are also given in the habitat survey data in Appendix 5.

Recreational fisheries for salmon and trout on the Allan Water are a significant local amenity and support local economic activity. The socio-economic potential of the fishery is impaired by the sub-optimal recruitment of fish, mainly caused by man-made obstacles. These have inhibited the use of all naturally available habitat that may be used to recruit new fish to the fishery. The target species of the fishery, salmon and trout, are known to enter the Allan Water from April and subsequently spread throughout the main river before entering the tributaries in the autumn (in higher water flows) to spawn. It is noted that the initial migration of migratory salmonid fish through the main river is likely to be delayed by Ashfield Weir (approximately 10 km from the River Forth confluence; see Section 5.2) where fish kills have been recorded in low flow conditions. Additionally, the weir may also influence the distribution of other species in the catchment, but this requires further data to establish if this is the case.

A number of man-made obstacles to fish passage have also been identified in the tributaries, which influence the use of spawning and juvenile nursery habitat of fish. Partial obstacles may be passable in optimal flow conditions and water temperatures but may also significantly delay or prevent migration entirely in some years when optimal flow conditions do not occur. Even if fish are able to pass such obstacles it may have further implications for the subsequent use of the habitat found upstream due to the limited energy resources of spawning adult fish, and therefore even partial barriers need to be considered as a significant influence on local fish populations. Full barriers to fish migration are more easily identified by fish surveys but their influence on the fish population may vary according to the area and quality of the habitat found upstream.

The obstacles identified here have been created by a number of developments in local infrastructure over a long period of time, but it is the upgrading of the A9 trunk road which appears to have had a particularly significant influence on the movement of fish into the tributaries flowing from the south. The culverted stream crossings are poorly designed in terms of fish migration and their location in the lower part of these tributaries has meant that relatively large areas of habitat have become disconnected and are no longer able to support the recruitment of migratory fish.

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Figure 5.3: Examples of culverts beneath the A9

5.3.2 Danny Burn A combination of three obstacles to fish passes were assessed on the Danny Burn: the A9 stream crossing, a sediment retaining wall and the distillery water offtake weir upstream of the culvert. Fish data available (RFFT, 2015) indicate that the distillery water offtake weir is a full barrier to salmon and non- salmonid fish and a full or partial barrier to trout moving upstream. These data also suggest that the sediment retaining wall and downstream culverts contribute to a significant decrease in upstream fish densities. Assessment of habitat upstream of the obstacles show a large area (6050m2) of good quality mixed habitat for salmon and trout recruitment over a 2 km length of stream and is therefore a high priority for fish and fisheries interests.

5.3.3 Buttergask Burn Two obstacles to fish passage were assessed on the Buttergask Burn: the A9 stream crossing and Buttergask Weir approximately 400 m upstream. Fish data (RFFT, 2012 and 2015) suggest that the culvert is a full barrier to salmon migration and both are partial barriers to trout. Initial assessment indicates that the fish habitat is of moderate-to-high gradient channel between the culvert and the weir. There is some (756m2) of habitat suitable for trout recruitment upstream of weir but diffuse pollution (fine sediments in the stream bed) impair the condition of the habitat and is therefore of low priority for fish and fisheries interests.

5.3.4 Burn of Ogilvie Fish data (RFFT, 2015) indicate that the A9 culvert stream crossing over the Burn of Ogilvie is a partial barrier to salmonid fish and may be a full barrier in some years possibly when the optimal flow conditions do not occur (densities decrease from 0.32 to 0.23 salmon/m2, and from 0.76 to 0.53 trout/m2). There is a relatively large area (4800m2) of good mixed habitat suited to salmonid fish recruitment upstream of the culvert and is therefore a high priority for fish and fisheries interests.

5.3.5 Rhynds Burn Two obstacles have been assessed, the lower of which is the spillway from the lower reservoir and the upper structure is the spillway between the lower and upper reservoirs. Fish data (RFFT, 2015) suggest that the lower spillway is a full barrier to salmon and trout. The similar design of the upper spillway suggests that this is also a full barrier to fish migration and therefore the restoration of fish passage is required at both spillways if fish are to be able to reach a small area of fish habitat in two tributary streams (recorded as 0m2 in RFFT and AWAIA habitat survey). These tributary stream have limited resources for salmonid fish recruitment and Rhynds Burn is therefore of low priority to fish and fisheries.

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5.3.6 Millstone Burn The Millstone Burn is a moderate-to-high gradient section of stream with patches of suitable habitat for recruitment of salmonid fish located between less suitable bedrock substrates. Fish surveys (RFFT, 2015) found that salmon and trout are present downstream of lower obstacle (weir) while only trout are found in 1650m2 of habitat upstream of the weir (downstream of the A9 culvert obstacle). Bedrock cascade obstacles located between the lower weir and the A9 culvert may be a full or partial barrier to salmon. The easement of the upper A9 culverted stream crossing is required in addition to the lower weir barrier to provide fish access to a further 874m2 of mixed habitat suited to trout recruitment upstream of the A9 culvert and easing these obstacles are therefore a moderate priority for fish and fisheries interests.

5.3.7 Feddal Burn The Feddal Burn is a moderate-to-high gradient section of stream habitat with patches of suitable habitat for recruitment of salmonid fish between and upstream of the obstacles which are associated with the construction of a series of in-line ponds along the study section. Salmon and trout are present downstream of lower obstacle (abstraction weir) and moderate densities of trout fry are found upstream of both obstacles (RFFT, 2015). The upper pond has filled with sediment and the stream habitat downstream appears to be starved of substrates, which impairs the condition of the habitat for fish. There is approximately 980m2 of mixed habitat suited to trout upstream of the upper pond which is a moderate priority for fish and fisheries interests.

5.3.8 Muckle Burn The Muckle Burn is a low-to-moderate gradient section of stream habitat with suitable habitat for recruitment of salmonid fish downstream and upstream of the weir obstacle. Salmon and trout densities upstream of the weir suggest that the weir is a partial barrier to salmon and possibly trout and is a full barrier to other species (RFFT, 2011). There is more than 15,000m2 of good quality habitat suited to salmon and trout recruitment upstream of the weir which makes the easement of this obstacle a high priority for fish and fisheries. Given the area of habitat available upstream, the obstacle is likely to have a significant impact on the use of this habitat and the production of juveniles and smolts.

5.3.9 Park Burn The Park Burn at Wester Cambushinnie is a relatively high gradient section of stream habitat with limited patches of suitable habitat for recruitment of trout between a series of in-line ponds, which create a series of impassable obstacles to upstream and downstream passage of fish. The condition of habitat for fish (trout) is impaired by channel modification and heavily grazed riparian habitat and fine sediment. Trout numbers (RFFT, 2015) downstream of the obstacles are similar to numbers found in the small area of habitat found upstream of obstacles (135m2) and is therefore of low priority to fish and fisheries interests.

5.3.10 Auchinlay Burn Downstream of the culvert obstacle at the A9 stream crossing, there is a short area of stream habitat (30 m long and 2.5 m wide) upstream of the confluence of the Allan Water where fish surveys have found trout to be present (RFFT, 2015). No fish were found by survey upstream of the culvert. The habitat upstream of the culvert is a relatively small area (545m2) of mixed habitat suited to trout and is therefore a low priority for fish and fisheries interests.

5.3.11 Scouring Burn The Scouring Burn has a number of natural cascades acting as partial obstacles downstream of the railway line and associated Sediment Retention Wall, which are passable to salmonid fish in elevated flow

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conditions. Fish surveys (RFFT, 2011) found both salmon and trout to be present downstream of a Sediment Retention Wall and railway culvert and only a lower density of trout upstream which suggest that the wall is a full barrier to fish. There is a relatively large area (2550m2) of good mixed habitat suited to salmonid fish recruitment upstream of the wall and is therefore a high priority for fish and fisheries interests.

5.3.12 Allan Water (Ashfield Weir) Ashfield Weir on the mainstem Allan Water is known to be a partial barrier to salmonid fish and possibly a full barrier to other non-salmonid species. The weir is located at the head of a long (100 m or more) set of natural bedrock cascades and waterfall obstacles. Water flow in the upper half of the natural obstacle is also likely to be affected by water abstraction for the hydroelectric generation scheme at this weir. Given the weir is located in the lower part of the catchment on the main Allan Water, this is a high priority for fish and fisheries interests as significant expenditure of energy and delays in migration have implications for the migration of fish into the rest of the catchment and ability to ascend other obstacles assessed by this study.

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6 Discussion: Catchment Plan

6.1 Catchment scale planning considerations There are a wide range of types and sizes of barrier to fish migration in the Allan Water catchment, which are fully or partially impeding access for the full range of native migratory fish species to available spawning habitat in the upstream tributaries.

A comprehensive and robust plan for addressing the issues caused by these structures needs to consider each structure within the context of the catchment as a whole. Generally, fish passage improvement projects tend to be most effective if starting at the most downstream barriers and working up the system. This helps to ensure that the effectiveness of each solution is not limited by the remaining barriers in place downstream.

However, the Allan Water catchment is more complicated because so many of the key barriers are on tributaries. Assuming that fish passage along the mainstem Allan Water is unimpeded (except for Ashfield Weir, which will be discussed separately), the order in which the barriers on a tributary-by-tributary basis are addressed is not an overriding concern. It is more important to consider each tributary as a standalone river reach, and prioritise each tributary (and the barriers on it) in terms of the benefit to fish habitat availability it will provide as well as the ease of achieving fish passage improvement. The prioritisation of tributaries is set out in Section 6.2, and used to inform the prioritisation of barriers in Section 6.3.

It may be worth seeking within each tributary to address the most downstream barrier first, however given that many of the barriers on the same tributary tend to be located close to one another and are often owned by the same individual or organisation, the exact order may not have a big influence on the effectiveness of these solutions in the medium to long term. In some cases it may also be beneficial to undertake construction works on several sites along one tributary in one go (if possible) to save costs relating to, for example, mobilisation, equipment hire and by sharing the site compound.

In the context of the wider catchment, it has been argued that Ashfield Weir is one of the most high priority sites as the ease of fish passage at this weir essentially controls the species, quantity and health of fish subsequently accessing the remaining upstream catchment. Whilst there is a fish pass at this site, it is argued that it is essential to ensure that this pass works as effectively as possible for as many native migratory species as possible (including eel and lamprey) in order to maximise the benefits of fish passage improvement works on the nine Task 1 sites and five Task 2 sites upstream. The same can also be said for any further barriers and fish passes downstream between Dunblane and the Firth of Forth (noting that this reach was outside the study area for this project).

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6.2 Catchment scale prioritisation To inform the catchment plan, the review of fisheries and habitat data has been used to produce a prioritised list of the tributaries considered in this study in Table 6.1. This list has been based on the benefits (habitat available upstream of barriers) of addressing the fish passage issues caused by barriers along each tributary. The lower end of Allan Water where Ashfield Weir is located has also been included.

Table 6.1 Catchment scale prioritisation of tributaries in the Allan Water catchment Significant barriers to fish Upstream habitat availability (above Tributary Priority migration uppermost barrier)

Mainstem All of upper catchment >240,000m2 (ca. 10m  Ashfield Weir (Task 2) High Allan Water width and 24,000m length) More than 15,000m2 (ca. 3m width and Muckle Burn  Muckle Weir (Task 1) 5,000m length) of good quality habitat suited High to salmon and trout recruitment upstream

 Danny Weir (Task 1) 6,050 m2 (ca. 2.75m width and 2,200m Danny Burn  Danny Burn A9 culverts and length) of good quality mixed habitat for High sediment retaining wall (Task 2) salmon and trout recruitment Over 4,800m2 (ca. 2m width and 2,400m Burn of  Burn of Ogilvie A9 culvert (Task length) of good mixed habitat suited to High Ogilvie 2) salmonid fish recruitment upstream 2,500m2 (ca. 1.7m width and 1,500m length) Scouring  Sediment Retention Wall (Task of good mixed habitat suited to salmonid fish High Burn 1) recruitment upstream

 Feddal abstraction (Task 1) 980m2 (ca. 1.4m width and 700m length)of Feddal Burn  Feddal Dam (Task 1) Mod. mixed habitat suited to trout upstream  Feddal Burn rock ramp (Task 2)

 Millstone Weir (Task 1) 874m2 (ca. 2.3m width and 380m length) of Millstone  Greenloaning A9 culverts (Task mixed habitat suited to trout recruitment Mod. Burn 1) upstream 756m2 (ca. 1.8m width and 420m length)of  Buttergask Weir (Task 1) Buttergask habitat suitable for trout recruitment upstream  Buttergask Burn A9 culverts Low Burn of weir but diffuse pollution impairs habitat (Task 2) quality Small area of habitat 135m2 (ca. 0.9m width  Wester Cambushinnie Dam Park Burn and 150m length) found upstream of Low (Task 1) obstacles Small area of mixed habitat 545m2 (ca. 1.25m Auchinlay  Auchinlay Culvert (Task 1) width and 436m length) suited to trout Low Burn upstream Two small tributary streams above upper  Lower Rhynds Dam (Task 1) reservoir, with limited resources for salmonid Rhynd Burn Low  Upper Rhynds Dam (Task 2) fish recruitment (recorded as 0m in RFFT and AWAIA habitat survey)

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Table 6.1 shows that there are clearly some key areas of priority for fish passage work in this catchment based on upstream habitat availability alone. The next step is to combine this information with understanding of the ease (or cost) of achieving fish passage improvement at each structure within these tributaries.

6.3 Prioritisation of Task 1 and Task 2 barriers To develop the catchment plan, the findings from the Task 1 and Task 2 surveys have been combined with the review of fisheries and habitat data to produce a prioritisation of barriers in Table 6.2. This assessment is based on the ease of achieving fish passage improvements at each structure, combined with the benefit to fish habitat availability assessment in Section 6.2. This has also been presented in map form in Figure 6.1.

The ease (or cost) of achieving fish passage improvement at each structure incorporated a range of considerations, including nearby infrastructure and/ or designated sites, the accessibility of the site and the extent of works that would be needed in order to restore fish passage for as many native migratory fish species as feasible. It follows that it is likely to be easier to restore fish passage at those barriers which are currently already considered to be passable to some species under a certain range of flows. In line with the aim of this project to identify simple solutions to barriers and fish passage issues if there is one, these structures that are only partial barriers to fish migration are often considered higher priority than full barriers, as simpler and cheaper solutions are available at these sites to provide benefits to a wide range of species.

The matrix below shows how the overall priority level for each site was derived based on the priority of the tributary (in terms of upstream habitat availability) and the priority of the site (in terms of the ease of achieving improvement). Habitat availability was the overriding consideration in this assessment.

Upstream habitat availability for tributary High Moderate Low High HIGH MODERATE MODERATE Ease of achieving improvement for Moderate HIGH MODERATE LOW individual structure Low MODERATE MODERATE LOW

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Table 6.2 Catchment scale prioritisation of barriers in the Allan Water catchment Upstream Ease of Overall Barrier Tributary habitat achieving Justification priority availability improvement Potential simple solution here to improve passage to a significant area of upstream habitat. Moderate modifications to Muckle Weir (Task Muckle Burn High High HIGH existing structure, most works can be carried out by the 1) landowner themselves (with support from RFFT and AWAIA) plus engineering support. Moderate modifications to existing fish pass and limited Ashfield Weir Mainstem High Moderate HIGH additional risk in return for very high benefit in terms of access to (Task 2) Allan Water upstream habitat. Relatively minor modifications to existing structure, to enable Burn of Ogilvie A9 Burn of access to moderate area of habitat upstream. Flow and High Moderate HIGH culvert (Task 2) Ogilvie sediment modelling needed to inform discussion with Transport Scotland.

Clear current user benefiting from this relatively small structure Danny Weir (Task Danny Burn High Moderate HIGH and mechanism (CAR licence) for delivering and maintaining fish 1) passage improvements to large area of upstream habitat.

Danny Burn A9 Relatively minor modifications to existing structure, to improve culverts and effectiveness of Danny Weir fish pass for large area of upstream Danny Burn High Moderate HIGH sediment retaining habitat. Flow and sediment modelling needed to inform wall (Task 2) discussion with Transport Scotland. Moderate modifications to existing structure needed in return for Sediment high benefit in terms of access to upstream habitat. Flow and Retention Wall Scouring Burn High Moderate HIGH sediment modelling needed to inform discussion with Network (Task 1) Rail.

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Upstream Ease of Overall Barrier Tributary habitat achieving Justification priority availability improvement Potential simple solution here, works can be undertaken directly Feddal abstraction and relatively cheaply by the landowner themselves (with Feddal Burn Moderate High MODERATE (Task 1) support from RFFT and AWAIA) in return for moderate benefit in terms of upstream habitat access.

Moderate modifications to existing structure in return for Millstone Weir Millstone Burn Moderate Moderate MODERATE moderate benefit in terms of upstream habitat. Flood risk and (Task 1) sediment modelling needed to inform risk to nearby properties.

Relatively minor modifications to existing structure in return for Greenloaning A9 moderate benefit in terms of upstream habitat. Flow and Millstone Burn Moderate Moderate MODERATE culverts (Task 1) sediment modelling needed to inform discussion with Transport Scotland.

Moderate modifications to existing rock ramp structure, limited Feddal Burn rock Feddal Burn Moderate Moderate MODERATE risks in return for moderate benefit in terms of upstream habitat ramp (Task 2) access.

Potential simple solution here, works can be undertaken directly Buttergask Weir Buttergask and relatively cheaply by the landowner themselves (with Low High MODERATE (Task 1) Burn support from RFFT and AWAIA) to enable access to low quantity and quality of upstream habitat.

Significant engineering work required to enable fish to access

the pond in return for moderate benefit in terms of upstream Feddal Dam (Task Feddal Burn Moderate Low MODERATE habitat access. Significant monitoring, flood risk and sediment 1) modelling required to inform risk to downstream assets.

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Upstream Ease of Overall Barrier Tributary habitat achieving Justification priority availability improvement Relatively minor modifications to existing structure, to improve Buttergask Burn Buttergask effectiveness of Buttergask Weir fish pass work for small area of A9 culverts (Task Low Moderate LOW Burn upstream habitat. Flow and sediment modelling needed to 2) inform discussion with Transport Scotland. Wester Significant design and construction requirements for Cambushinnie Park Burn Low Low LOW recommended bypass channel (and bridge/ culverts under road) Dam (Task 1) for little benefit in terms of upstream habitat. Very large structure in a nature reserve. Significant engineering Lower Rhynds work required to enable fish to access reservoir for little benefit. Rhynd Burn Low Low LOW Dam (Task 1) Considerable survey requirements in advance of any design work. Very large structure in a nature reserve. Significant engineering Upper Rhynds work required to enable fish to access reservoir for little benefit. Rhynd Burn Low Low LOW Dam (Task 2) Considerable survey requirements in advance of any design work. Significant changes required to existing structure below major Auchinlay Culvert Auchinlay Low Low LOW trunk road, likely to include significant disturbance to road users, (Task 1) Burn for little benefit in terms of upstream habitat.

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Key: (! High Ease of Achieving Improvement ± (! Moderate Ease of Achieving Improvement (! Low Ease of Achieving Improvement High Upstream Habitat Availability Moderate Upstream Habitat Availability Low Upstream Habitat Availability

Upper Rhynds Dam Rivers and Water Bodies Lower Rhynds Dam (! (!

Feddal Dam (! Feddal Buttergask Burn Danny Burn A9 Culverts Abstraction Buttergask Burn A9 Culverts and Sediment Retaining Wall (!(! (! (! (! Feddal Burn (! Danny Weir Rock Ramp Buttergask Weir (! Burn of Ogilvie A9 Culvert Title Catchment Scale Prioritisation of Reaches and Barriers (! Millstone Weir Muckle Weir (! (! Project Wester Cambushinnie Dam Greenloaning Allan Water Barrier Easement Project Phase 1 (! A9 Culverts

Client River Forth Fisheries Trust

Date Scale

19/02/2016 1:60000

Figure

Figure 6.1 (! Ashfield Wier

Drawn by Checked by Number

JP CR v1

Auchinlay Culvert (!

(! Sediment Retention Wall

(! 0 Dunbla1n,2e50 2,500 Meters © Crown Copyright and database rights 2015

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Based on this assessment, the following order of priority is proposed for fish passage work in the Allan Water catchment (from highest to lowest). Note actions are grouped by tributary as the benefits of tackling barriers in isolation from others on the same tributary are considered to be limited. The tributaries are ranked in individual order of priority (incorporating factors such as the number and complexity of barriers on the tributary), as well as being grouped under the main categories of High, Moderate and Low Priority for addressing barriers in that tributary or river reach as a whole :

HIGH PRIORITY 1. Muckle Burn: Modification of Muckle Weir (Task 1). 2. Mainstem Allan Water: Modification of fish pass on Ashfield Weir (Task 2). 3. Burn of Ogilvie: Modification of A9 culvert (Task 2). 4. Danny Burn: Replacement of Danny Weir (Task 1) and modification of A9 culverts and sediment retaining wall (Task 2). 5. Scouring Burn: Technical fish pass on Sediment Retention Wall (Task 1).

MODERATE PRIORITY 6. Millstone Burn: Modification of Millstone Weir (Task 1) and modification of Greenloaning A9 culverts (Task 1). 7. Feddal Burn: Modification of Feddal abstraction (Task 1), modification of Feddal Burn rock ramp. (Task 2) and phased removal of Feddal Dam (Task 1). 8. Buttergask Burn: Removal of Buttergask Weir (Task 1) and modification of A9 culverts (Task 2).

LOW PRIORITY 9. Park Burn: Bypass channel for Wester Cambushinnie Dam (Task 1). 10. Rhynd Burn: Modification to spillway from Lower Rhynds Dam (Task 1) and Upper Rhynds Dam (Task 2). 11. Auchinlay Burn: Replacement of Auchinlay Culvert (Task 1).

6.4 Factors limiting response to mitigation The biggest factor limiting ecological response to fish passage improvements in the Allan Water catchment is the interdependency between different barriers located upstream and downstream of one another, which has been discussed further in the earlier part of this Section.

Further to that, another limiting factor that may be significant even if fish passage mitigation measures are put in place at all sites is sediment transfer and other geomorphological processes. Many of the barriers to fish migration covered by this study are also a barrier to sediment movement downstream, as discussed in the Task 1 survey sheets in Appendix 2. Impoundment of sediment upstream of these structures limits the quality of the downstream habitat for fish, in particular by restricting the amount of suitable spawning gravels available (Feddal Burn is a notable example). Where possible it was recommended that these structures be fully or partially removed to enable the full range of geomorphological processes to be restored, however this was not always considered to be the most feasible or appropriate, particularly as many barriers are associated with a specific use such as retaining water for abstraction. Under these circumstances, many barriers will continue to impound sediment upstream even once fish passage issues have been addressed, and it is therefore recommended that a sediment management plan is included in the CAR licence for the barrier where feasible. It is noted that transfer of sediment up to 10m upstream of an impoundment to the reach immediately downstream can be covered by the General Binding Rules under the CAR guidance (GBR12).

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Two localised factors limiting ecological response to fish passage improvements were noted in the field. The first is the presence of invasive species (giant hogweed) along the Millstone Burn, Feddal Burn and Auchinlay Burn, which has the potential to spread to the wider catchment. The RFFT are seeking to address these issues in parallel with fish passage improvement works through the Forth Invasive Non Native Species Programme. In addition, a strict protocol is needed for wash downs on all work sites where seed in the soil may be spread and colonise new areas. The second factor is diffuse pollution (fine sediments in the stream bed), noted particularly in Buttergask Burn due to poaching of the soft river banks, which impairs the condition of the habitat for fish downstream. Engagement with the landowner to discuss suitable livestock management measures alongside barrier easement works in this catchment is therefore also recommended to improve the benefits of this work for fish.

Based on the site survey and WFD data available for the water bodies in the Allan Water catchment, there are two further catchment scale pressures (both on the mainstem Allan Water) which could limit the ecological and morphological recovery once mitigation measures are implemented: 1. Change from natural flow conditions (for renewable electricity and aquaculture). 2. Depletion of base flow from groundwater body (abstraction for mineral water production).

It is recommended that discussions are held throughout this process with key stakeholders involved in addressing these other pressures (abstractors and SEPA), to improve the effectiveness of measures to restore fish migration and river habitats in the Allan Water catchment.

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7 Conclusions and Recommendations

This project has used a combination of desk-based studies and site surveys to undertake a technical assessment of structures and identification of next steps for the eleven barriers identified by SEPA and RFFT as barriers to fish migration, considering the mitigation options available to restore fish passage at each and review the impact of additional features in the Allan Water catchment that might limit the effectiveness of mitigation measures for restoring fish passage in these rivers.

The study has produced a prioritised list of barriers for the next phased of work, grouped by tributary. High priority tributaries have the maximum benefit in terms of upstream habitat availability and the lowest number and difficulty of options to be implemented. The final recommended order of prioritisation (from highest to lowest) is:

1. Muckle Burn: Modification of Muckle Weir. 2. Mainstem Allan Water: Modification of fish pass on Ashfield Weir. 3. Burn of Ogilvie: Modification of A9 culvert. 4. Danny Burn: Replacement of Danny Weir and modification of A9 culverts and sediment retaining wall. 5. Scouring Burn: Technical fish pass on Sediment Retention Wall. 6. Millstone Burn: Modification of Millstone Weir and modification of Greenloaning A9 culverts. 7. Buttergask Burn: Removal of Buttergask Weir and modification of A9 culverts. 8. Feddal Burn: Modification of Feddal abstraction, modification of Feddal Burn rock ramp and phased removal of Feddal Dam. 9. Park Burn: Bypass channel for Wester Cambushinnie Dam. 10. Rhynd Burn: Modification to spillway from Lower Rhynds Dam and Upper Rhynds Dam. 11. Auchinlay Burn: Replacement of Auchinlay Culvert.

In addition to the specific recommendations for each site set out in earlier Sections, this report has made the following general recommendations:

According to a 2006 report by the AWAIA, at least seven of these structures (including most of the culverts) have a CAR licence attached to them, and most structures without a licence are likely to require one in future, particularly where they provide a clear benefit to the owner (e.g. for abstraction or to reduce flood risk). It is therefore recommended that the RFFT confirm what the requirements of the CAR licence are for each structure through discussion with SEPA, as that may provide an alternative driver for restoring fish passage at each site.

Several of the structures were identified as being in relatively poor condition, or likely to need regular checks and maintenance (e.g. to support an abstraction). In these cases it is recommended that the RFFT discuss with the barrier owner if/ when there are plans to renew the structure, as this could be the best opportunity to incorporate a more “fish friendly” design.

Similarly, it was noted that the organisation responsible for the largest number of these structures is Transport Scotland. It is therefore recommended that the RFFT (and SEPA, as appropriate) engage with the Asset Protection team at Transport Scotland at an early stage to discuss their concerns and priorities for A9 culvert management, and to identify potential opportunities for fish passage improvement based on their planned programme of repair and replacement works. A similar approach is recommended with the Asset Protection team at Network Rail for Scouring Burn.

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The project has identified several relatively small sites where simple fish passage improvement works could be carrier out by the landowner. It is therefore recommended that the RFFT (and SEPA, as appropriate) explore available funding mechanisms for this type of work with local landowners which would help to encourage fish passage improvements at these sites.

Additional work is needed to address the limiting factors discussed in Section 6.4 that may inhibit the recovery of fish passage in the Allan Water catchment even if barrier easement works are put in place. They are: 1. Implement a sediment management plan (e.g. through the CAR licence) to address barriers to sediment movement where these cannot feasibly be removed as part of the barrier easement works. 2. Continue to tackle the spread of invasive species (particularly giant hogweed) in the Allan Water catchment. 3. Engagement with landowners to discuss suitable livestock management measures alongside barrier easement works in catchments with diffuse pollution issues (fine sediments in the stream bed). 4. Engage with SEPA and key water abstractors in the catchment (for mineral water, aquaculture and renewable electricity) to limit changes from natural flow conditions along the mainstem Allan Water.

Allan Water is a catchment with some excellent areas of upstream habitat for fish, where the use of these habitats is limited by a range of different structures which act as a barrier to fish migration. This study is an important step towards identifying suitable ways of addressing these issues for each barrier in order to create a healthier and more resilient river ecosystem for the future in the Allan Water catchment as a whole.

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