Item 7 - Clydebank Surface Water Management Plan
West Dunbartonshire Council · 19 August 2026
Back to Infrastructure, Regeneration & Economic Development Committee — 19 August 2026 and its agenda
Text extracted from the council's PDF. Layout and reading order may differ from the original.
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Unmarked WEST DUNBARTONSHIRE COUNCIL Report by Chief Officer Roads and Neighbourhood Infrastructure, Regeneration and Economic Development on 19 August 2026 Subject: Clydebank Surface Water Management Plan 1. Purpose 1.1 The purpose of this report is to present the findings of the Clydebank Surface Water Management Plan (SWMP) and to seek Members' agreement of the proposed strategic approach to managing surface water flood risk across Clydebank. 1.2 The report provides an overview of the principal flooding mechanisms identified within the catchment area, summarises the updated hotspot assessment, and outlines the recommended future actions required to develop a coordinated and sustainable flood risk management programme. 2. Recommendations 2.1 It is recommended that the Committee: a) Note the completion of the Clydebank Surface Water Management Plan; b) Note that surface water flooding and the sewer network capacity have been identified as the principal causes of flooding at a number of locations across Clydebank; c) Note the revised hotspot assessment following publication of the 2025 SEPA Flood Maps; d) Agree the recommendation that future flood mitigation measures are developed through a collaborative catchment-wide approach involving West Dunbartonshire Council, Scottish Water, SEPA, Network Rail and Scottish Canals; e) Support continued collaboration with Scottish Water through development of the Dalmuir System Plan and associated sewer flood investigations; and f) Note that future capital projects will be subject to detailed appraisal, design development, funding allocation and committee approval. ITEM 7
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Unmarked 3. Background 3.1 Under the Flood Risk Management (Scotland) Act 2009, local authorities are required to undertake Surface Water Management Planning within areas identified through Scotland's Flood Risk Management Planning process. Clydebank was identified within the Clyde and Loch Lomond Local Flood Risk Management Plan as requiring further assessment of surface water flood risk. 3.2 West Dunbartonshire Council commissioned a consultant to undertake a Surface Water Management Plan for Clydebank. The original report was completed in April 2024 and subsequently reviewed following publication of updated SEPA Flood Maps in 2025, stakeholder workshops and ongoing Scottish Water investigations. 3.3 The study area forms part of a Potentially Vulnerable Area (PVA) where approximately 1,800 people and 1,200 homes and businesses are currently estimated to be at risk of flooding. Climate change projections indicate this could increase to approximately 2,700 people and 1,700 homes and businesses by 2080. 3.4 Responsibility for flood risk management in Clydebank is shared across a number of partners as well as individual property owners. 3.5 West Dunbartonshire Council is responsible for: • Road drainage and gullies; • Local flood risk management duties under the Flood Risk Management (Scotland) Act 2009; • Emergency planning and response; • Planning and development management; and • Maintenance of Council owned drainage assets and watercourses where applicable. 3.6 Scottish Water responsibilities include: • Public sewer networks; • Investigating sewer flooding; • Delivering investment through programmes such as the Dalmuir System Plan; and • Maintaining public freshwater infrastructure. 3.7 SEPA responsibilities include: • National flood mapping; • Flood forecasts and alerts; and • Strategic flood risk management planning. 3.8 Other stakeholders such as Network Rail, Scottish Canals and developers will also have a key role to play where their assets influence drainage or flooding patterns.
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Unmarked 3.9 Additionally local property owners can take measures to address flood risks locally through proper maintenance of private drains and drainage systems within their boundary, taking reasonable steps to protect their property from flooding and through continued reporting of flooding incidents to the Authority to support and develop the understanding of flood risk in the area. 3.10 The Surface Water Management Plan was developed in accordance with Scottish Government guidance and follows the recognised approach of: • Understanding flood risk; • Identifying flood hotspots; • Establishing objectives; • Appraising mitigation measures; • Developing recommendations and future actions. 4. Main Issues 4.1 A comprehensive assessment of flood risk was undertaken to identify the vulnerable locations, understand the likelihood and potential impacts of flooding and to identify the root cause at each identified hotspot. By developing a clear understanding of underlying flood mechanisms, it allows the service to ensure that appropriate and effective mitigation and adaption measures can be implemented. Historic flooding records, stakeholder information and hydraulic modelling outputs are essential when assessing flood risk and prioritising investment. The assessment included review of: • Historic flood records; • Scottish Water sewer data; • SEPA Flood Maps; • Hydraulic modelling; • Stakeholder information; • Site observations. 4.2 The study confirms that flood risk in Clydebank is not solely attributable to surface water runoff. Instead, flooding is often influenced by complex interactions between: • Surface water runoff; • Combined sewer network exceedance; • Watercourse interactions; • Highway drainage systems; • Local topography. 4.3 As part of the initial assessment potential surface water flood risk locations were identified using SEPA flood maps. Surface water occurs when rainfall generated runoff exceeds the capacity of the watercourse or drainage system resulting in water collecting on the surface and flowing overland.
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Unmarked The initial Surface Water Management Plan identified eleven flooding hotspots: 1. Second Avenue / Ramsay Street 2. Western Isles Road 3. Duntocher Road 4. Livingstone Street 5. Melbourne Avenue 6. Low Crescent 7. Dumbarton Road 8. Dunedin Terrace 9. Kilbowie Road 10. Station Road 11. Dumbarton Road (West) 4.4 The hotspots are defined as areas containing six or more residential and/or commercial properties which are located within areas which have a medium likelihood of experiencing a 1 in 200 year (0.5 Annual Exceedance Probability) event. In addition, any location where flooding could cause significant disruption to transport, access for emergency services or wider economic activity were also included. 4.5 As more data and understanding of flood risk is collected SEPA review and update the Flood Maps on a regular basis. After the publication of updated SEPA Flood Maps in 2025 the hotspots were reviewed to determine any changes to the extent and severity of surface water flooding.
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Unmarked 4.6 As a result of these revisions some hotspots identified from the initial assessment no longer met the required screening criteria. The updated maps highlighted the flood risk at several locations to be lower than previously understood. It should be noted that flood risk will remain present at these locations albeit at a reduced level than previously considered. Locations where flood risk is now considered lower than previously understood include: • Low Crescent; • Dumbarton Road; • Dunedin Terrace; • Livingstone Street (currently subject to further Scottish Water investigation). 4.7 The Linnvale area has been identified as a high impact area by Scottish Water and they are leading investigations to better understand the causes of flooding in this area. The outcome of these investigations will be crucial in understanding the flooding and identifying long term solutions. Despite the reduced risk at Livingstone Street flood risk remains an important consideration within the area and should be reviewed again after Scottish Water investigations are concluded. 4.8 From the original list, 6 locations were still considered to present significant flood risk. These include: Location Main Flooding Issue Second Avenue / Ramsay Street Surface water and sewer flooding Western Isles Road Surface water and drainage capacity issues Duntocher Road Surface water and sewer flooding Melbourne Avenue Surface water and sewer flooding Kilbowie Road Surface water flooding affecting commercial areas Station Road Surface water flooding affecting a key transport route 4.9 Full details of the root causes for each location are highlighted within section 4 of the Surface Water Management Plan however a review of the principal flooding mechanisms at each location highlights sewer capacity as a major contributor at all locations. 4.10 The report concludes that sewer capacity constraints within the wider Dalmuir catchment have a significant influence on flood risk. At Second Avenue, hydraulic modelling identified approximately 1,500m³ of predicted sewer flooding during a 1 in 30-year rainfall event, highlighting the significance of sewer capacity limitations in the area.
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Unmarked 4.11 The flooding experienced in Clydebank is increasingly understood to be a catchment-wide issue rather than a series of isolated local problems. Significant sewer flooding is a major contributing factor at several hotspots highlighting the importance of partnership working with Scottish Water. Ongoing investigations by Scottish Water may further improve our understanding of flood mechanisms, particularly within the Duntocher Road and Livingstone Street areas. 4.12 The Surface Water Management Plan highlights the need for a coordinated catchment-wide approach due to the interconnected nature of flooding mechanisms within Clydebank. Partnership working has already been established between: • West Dunbartonshire Council; • Scottish Water; • SEPA; • Scottish Canals; • Network Rail. The report recommends that future investment and intervention planning is aligned with Scottish Water's Dalmuir System Plan to maximise opportunities for joint funding and delivery. 4.13 The Surface Water Management Plan considered a wide range of structural and non-structural flood mitigation measures to develop appropriate solution options at each of the hotspot locations. The interventions considered included: • Sustainable Drainage Systems (SuDS); • Swales; • Surface water attenuation basins; • Rain gardens; • Permeable paving; • Surface water separation; • Underground storage; • Enhanced maintenance regimes; • Blue-green infrastructure. • Additional investigation and study • Opportunities for property level protection • Flood forecasting and warning 4.14 These solutions were further assessed against a multi-criteria assessment to reduce the number of priority measures taken forward and focus the options on those which will provide the most viable means of managing flood risk.
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Unmarked Multi-Criteria Assessment Scoring 4.15 The categorisation reflects the latest understanding of flood risk based on historic flooding records, hydraulic modelling, stakeholder engagement and the updated 2025 SEPA Flood Maps. The categorisation will be reviewed regularly as further information becomes available through Scottish Water investigations and future flood events. 4.16 To support decision making and future investment planning, the hotspots were prioritised against set criteria to identify which factors should be addressed first (short term) and which factors can be addressed in the medium and long term. 4.17 This initial list of prioritise has been reviewed as part of the option appraisal process. Whilst detailed appraisals were undertaken for high priority hotspots, medium and low priority actions were also subject of a high-level assessment to identify potential future actions and investigations. Hotspot Interventions and costs Hotspot Name Priority Preferred Option Indicative Capital Cost Range Short Term Actions (0-2 years) Indicati ve Cost Second Ave/Ramsay Street High Attenuation basin at junction and school- based storage measures £0.8m- £2.0m Detailed flood study and design scoping £0.10m Western Isle Road High Roadside swales and attenuation measures £0.3m - £0.8m Detailed flood study and design scoping £0.05m Duntocher Road High SuDS basin adjacent to Kilbowie Roundabout £0.8m - £1.8m Detailed flood study and design scoping £0.10m Livingstone Street High SuDS basin and associated drainage works £0.5m – £1.2m Detailed flood study and design scoping depending on SW investigations £0.08m Station Road Medium Consider future appraisal of options focused on protecting access and transport resilience if flooding continues to affect the route. n/a Detailed flood study and options appraisal £0.05m
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Unmarked Kilbowie Road Medium Consider future appraisal of options n/a Detailed flood study and options appraisal £0.05m Melbourne Avenue Low Swale and underground geocellur storage £0.6m - £1.5m Detailed flood study and design scoping £0.07m Low Crescent Low Not included in option appraisal but should be reviewed as more information is received n/a Monitor and continue data collection n/a Dumbarton Road Low Not included in option appraisal but should be reviewed as more information is received n/a Monitor and continue data collection n/a 4.18 In the short term it would also be recommended to continue to develop a better understanding of flooding in the area through partnership working. Proposed actions would also include: • Completion of Scottish Water investigations at Duntocher Road, Livingstone Street and the wider Dalmuir catchment. • Developing opportunities for joint investment with Scottish Water. • Continued flood recording and monitoring. • Updating of emergency response procedures. • Continuing to review 2025 SEPA mapping and hotspots as new data is collected. 4.19 The report points towards a medium to long-term programme of investment rather than a single flood scheme Period Actions Medium Term Programme (2 – 5 years) Reassess the preferred options using updated understanding of flood mechanisms Develop outline design and update cost estimates for interventions Seek funding opportunities/decisions and align to Scottish Water Investment plans Deliver any “quick win” interventions where appropriate, including SuDS, drainage improvements and runoff reductions Long Term Programme (5 to 15 years) Progress major flood alleviation schemes Deliver integrated sewer and surface water management projects Implement wider blue-green infrastructure Align with regeneration, roads and capital investment programmes Build resilience to projected climate change impacts
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Unmarked 4.20 The report advises that these options should not proceed directly to implementation until ongoing Scottish Water investigations are complete and flood modelling has been reviewed using the latest available information. 4.21 The Surface Water Management Plan is intended to provide a strategic framework for future flood risk management rather than an immediate construction programme. The next 2 to 3 years are likely to focus on ongoing investigations, partnership working and development of funding opportunities. Subject to the outcomes of Scottish Water's investigations and future capital programming, delivery of significant flood mitigation measures is likely to occur over a medium to long-term period of approximately 5 to 15 years. 4.22 Surface water flooding remains one of the most significant climate resilience challenges facing Clydebank. The combination of increasingly intense rainfall, ageing drainage infrastructure, urban development pressures and local topography continue to place pressure on existing drainage systems. 4.23 The Surface Water Management Plan provides a structured approach to understanding flood mechanisms, prioritising investment and identifying sustainable, long-term solutions. Through targeted infrastructure investment, nature-based drainage measures and continued partnership working, the Council can improve resilience, reduce flood risk and support the long-term wellbeing of communities across Clydebank. 5. People Implications 5.1 There are no direct staffing implications arising from adoption of the SWMP 6. Financial and Procurement Implications 6.1 There are no immediate financial implications arising from this report . 6.2 Future flood mitigation projects will require detailed design, appraisal and separate funding approvals. Potential funding sources may include: • Council capital budgets; • Flood Risk Management funding; • Scottish Water investment programmes; • Developer contributions; • External grant funding.
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Unmarked 7. Risk Analysis 7.1 If the SWMP recommendations are not progressed there is a risk of: • Continued flood damage to property and infrastructure; • Increased disruption to transport networks; • Reduced resilience to climate change impacts; • Increased maintenance liabilities; • Missed opportunities for partnership investment. . 7.2 Uncertainty remains regarding some flood mechanisms pending completion of ongoing Scottish Water investigations within the Dalmuir catchment 8. Equalities Impact Assessment (EIA) 8.1 An Equality Impact Assessment is not required for this report as it relates to the adoption of a strategic study and recommendations. 8.2 Individual mitigation projects will be assessed separately as they progress 9. Consultation 9.1 Preparation of the SWMP included consultation and engagement with: • Scottish Water; • SEPA; • Scottish Canals; • Network Rail; • West Dunbartonshire Council services. . 9.2 A stakeholder workshop was undertaken in December 2025 to consider flood mechanisms, opportunities for collaboration and future investment priorities 10. Strategic Assessment 10.1 The review sets out actions to support the successful delivery of the strategic priorities and objectives of the Council, in particular: • sustainable communities and resilient infrastructure Chief Officer Gail Macfarlane Service Area Roads and Neighbourhood Date: 5 August 2026
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Unmarked Person to Contact: Liam Greene, Roads and Transport Manager, Liam.greene@west-dunbarton.gov.uk Appendix Surface Water Management Plan Wards Affected: Clydebank Central Clydebank Waterfront