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Irwell Catchment Flood Management Plan Summary Report December 2009 managing flood risk We are the Environment Agency. It’s our job to look after your environment and make it a better place – for you, and for future generations. Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are making your environment cleaner and healthier. The Environment Agency. Out there, making your environment a better place.

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Environment Agency Richard Fairclough House Knutsford Road WA4 1HT Tel: 0870 8506506 Email: [email protected] www.environment-agency.gov.uk

© Environment Agency

All rights reserved. This document may be reproduced with prior permission of the Environment Agency. December 2009 Introduction

I am pleased to introduce our summary of the Irwell Catchment Flood Management Plan (CFMP). This CFMP gives an overview of the flood risk in the Irwell catchment and sets out our preferred plan for sustainable flood risk management over the next 50 to 100 years.

The Irwell CFMP is one of 77 CFMPs for and is the main area at risk and in 1946, some Wales. Through the CFMPs, we have assessed inland 5000 properties flooded. It is estimated that 7,500 flood risk across all of England and Wales for the properties in the catchment have a 1% probability of first time. The CFMP considers all types of inland fluvial flooding each year. We estimate that by 2100 flooding, from rivers, groundwater, surface water approximately 10,000 properties in the Irwell CFMP and tidal flooding, but not flooding directly from the area could be at risk of fluvial flooding. This is an 8% sea (coastal flooding), which is covered by Shoreline increase compared to the current number. Management Plans (SMPs). Our coverage of surface We cannot reduce flood risk on our own, we will and groundwater is however limited due to a lack of therefore work closely with all our partners to improve available information. the co-ordination of flood risk activities and agree The role of CFMPs is to establish flood risk management the most effective way to management flood risk in policies which will deliver sustainable flood risk the future. To develop this plan and ensure social, management for the long term. This is essential if we economic and environmental issues were taken are to make the right investment decisions for the into account we worked with, and consulted many future and to help prepare ourselves effectively for organisations. These include amongst others: AGMA, the impact of climate change. We will use CFMPs to Peel Ports, Defra, , Natural England and help us target our limited resources where the risks English Heritage. are greatest. This is a summary of the main CFMP document, if you This CFMP identifies flood risk management policies to need to see the full document an electronic version assist all key decision makers in the catchment. It was can be obtained by emailing enquiries@environment- produced through a wide consultation and appraisal agency.gov.uk or alternatively paper copies can be process, however it is only the first step towards an viewed at any of our offices in North West Region. integrated approach to Flood Risk Management. As we all work together to achieve our objectives, we must monitor and listen to each others progress, discuss what has been achieved and consider where we may need to review parts of the CFMP.

In the Irwell catchment, the main source of risk is flooding from rivers (fluvial flooding). Localised floods due to overloaded urban drainage/sewer systems, Tony Dean surface water and blocked culverts also occur. Regional Director

Environment Agency Irwell Catchment Flood Management Plan 1 Contents

The purpose of a CFMP in managing flood risk 3

Catchment overview 4

Current and future flood risk 6

Future direction for flood risk management 10

Sub-areas 1 City Centre to 12 2 Salford, Swinton and Eccles 14 3 to 16 4 Middleton, Radcliffe and 18 5 Bury, and 20 6 22 7 Rural Areas 24 8 Bradford and 26 9 Heywood, Whitefield and South 28 10 North Oldham, , Whitworth and Littleborough 30

Map of CFMP policies 32

Cover photo of used with permissions of Ian Roberts

2 Environment Agency Irwell Catchment Flood Management Plan The purpose of a CFMP in managing flood risk

CFMPs help us to understand the • Internal Drainage Board, water CFMPs aim to promote more scale and extent of flooding now companies and other utilities to sustainable approaches to managing and in the future, and set policies help plan their activities in the flood risk. The policies identified in for managing flood risk within the wider context of the catchment. the CFMP will be delivered through a catchment. CFMPs should be used combination of different approaches. • Transportation planners. to inform planning and decision Together with our partners, we making by key stakeholders such as: • Landowners, farmers and will implement these approaches land managers who manage through a range of delivery plans, • The Environment Agency, who will and operate land for projects and actions. use the plan to guide decisions agriculture, conservation on investment in further plans, The relationship between the CFMP, and amenity purposes. projects or actions. delivery plans, strategies, projects • The public and businesses to and actions is shown in figure 1. • Regional planning bodies and enhance their understanding local authorities who can use of flood risk and how it will the plan to inform spatial be managed. planning activities and emergency planning.

Figure 1 The relationship between CFMPs, delivery plans, projects and actions

Policy planning • CFMPs and Shoreline Management Plans. • Action plans define requirement for delivery plans, projects and actions.

Policy delivery plans (see note) Projects and actions • Influence spatial planning to reduce risk • Make sure our spending delivers the best and restore floodplains. possible outcomes. • Prepare for and manage floods • Focus on risk based targets, for example (including local Flood Warning plans). numbers of households at risk. • Managing assets. • Water level management plans. • Land management and habitat creation. Note: Some plans may not be led by us – we may • Surface water management plans. identify the need and encourage their development.

Environment Agency Irwell Catchment Flood Management Plan 3 Catchment overview

The River Irwell catchment drains mill buildings, reservoirs and the SSSIs are also Special Areas the highly urbanised area to the mill lodges. In addition there are of Conservation (SACs) including north of Manchester. The catchment a number of Scheduled Ancient The Rochdale and The South covers over 700 square kilometres Monuments (SAMs), and parts Pennine Moors which is also a and is home to over two million of Manchester and Salford have Special Protection Area (SPA). people. The towns with the highest recently been nominated as populations include Manchester, candidates for World Heritage Bolton, Oldham, Salford and Status. Rochdale. The main rivers are the The highly urbanised nature of Irwell, Roch, Croal, Medlock and Irk, the catchment means it is one of all of which flow (via the Irwell) into the least naturally wooded areas the . in the North West. Despite the The sources of the main rivers are predominance of urban areas, there found in the , where land are numerous nature conservation rises to 450 metres above sea sites of national and international level in the north and east of the importance, including 14 Sites of catchment. In the lower catchment, Special Scientific Interest (SSSIs) in the south and southwest, the including, , Hodge Clough, elevation is 20 metres above sea Tonge River Section, Longworth level. A large proportion of the Clough and Oak Field. Some of catchment’s geology and soils are relatively impermeable, meaning that water is more likely to remain on the surface than drain through to groundwater. There are many towns and two cities within the catchment, along with agricultural areas which include pasture for sheep and cattle, some of which are in upland moorland areas.

The rapid expansion of industrial development in the late 19th century and its subsequent decline in the late 20th century has left many of the watercourses in the Irwell catchment in a heavily modified condition, with many kilometres of walled banks and culverts. The same industry means the catchment has a rich cultural heritage, including a wealth of Flood storage Salford Basin in operation

4 Environment Agency Irwell Catchment Flood Management Plan Map 1 Irwell CFMP main features

Environment Agency Irwell Catchment Flood Management Plan 5 Current and future flood risk

Overview of the current flood risk

Flood risk has two components: to peak in these generally narrow • Sewer flooding is usually caused the chance (probability) of a valleys, and the local population by an inadequate sewer capacity particular flood and the impact (or has insufficient time to react or blockages within the network. consequence) that the flood would and reduce the consequences of Sewer flooding is known to affect have if it happened. The probability flooding. The flooding regime in parts of , Rochdale of a flood relates to the likelihood of these areas is often described as and Littleborough, as well as a flood of that size occurring within “flashy”. The middle catchment Bolton and Oldham and in part a one year period, it is expressed is characterised by a flatter and is thought to be due to run- as a percentage. For example, lower topography. Settlements off surcharging the drainage a 1% flood has a 1% chance or such as Bury, Radcliffe and systems. Sewers may also flood probability of occurring in any one Middleton are found here. The due to backing up as a result of year, and a 0.5% flood has a 0.5% time to peak is around four to five high river water levels during chance or probability of occurring in hours and for fluvial flooding to times of flood. Areas within any one year. The flood risks quoted occur here, it normally requires Salford and Manchester are in this report are those that take more widespread heavy rain and/ known to be affected by this type account of flood defences already in or a prolonged period of wet of flooding, although there are place. weather. The lower catchment limited records of this occurring is where the topography is in recent years. United Utilities The Irwell Catchment has a history the lowest, and is the most have an ongoing programme of of flooding with Salford being the extensively urbanised area of work to maintain and improve worst affected. In 1946 over 5000 the catchment, with the cities of public sewers. properties were flooded from the Manchester and Salford located • Even though the Irwell CFMP area River Irwell. A few years later Salford here. Flooding is caused by contains areas of permeable was flooded affecting 600 properties. widespread heavy rain and/or bedrock at or near the land surface The area has settlements close to prolonged periods of wet weather and some underlying the banks of the rivers due in part to throughout the catchment. The groundwater flooding is not seen the industrialisation in the 19th effects of these are twofold: as a major issue in the area. century. This means communities firstly, dangerously fast flowing are at risk of flooding from the Irwell water and, secondly, large areas and its many tributaries. Rochdale of ponded water up to two metres What is at risk? flooded in 1991 affecting over 80 deep. The Irk and the Medlock properties and join the Irwell in Manchester City Using hydraulic models and flooded in 1999 affecting over 50 centre and these rivers then flow floodmaps where no models exist properties. into the Manchester Ship Canal we estimate that 7,500 properties in the catchment have a 1% chance of The main sources of flooding in the where its flows are regulated. fluvial flooding each year. There are Irwell catchment are as follows: • Surface water flooding is caused five areas of special scientific interest • River flooding in the upper by water collecting or flowing (Nob End, Hodge Clough, Tonge River catchment affects the relatively over the surface before soaking Section, Longworth Clough and Oak small settlements and towns into the ground or entering Field) and one scheduled ancient such as Littleborough, Rochdale, a watercourse. This type of monument within the 1% annual , , Ramsbottom, flooding can occur throughout probability flood extent, which could , Whitworth and the catchment but usually only be affected by a flood. The Rochdale Rawtenstall. There is a short time causes a low level of risk. Canal (SSSI and SAC) has a small area at risk in an extreme flood. 6 Environment Agency Irwell Catchment Flood Management Plan Where is the risk? Table 1. Locations of Towns and Villages with 100 or more properties at risk in a 1% annual probability river flood The catchment has a history of flooding. Salford, Rochdale and Number of properties at risk Locations parts of the Rossendale Valley have been most affected by past fluvial Over 1000 Salford, flood events. In many of the areas at risk, socially vulnerable groups can 500 to 1000 Rossendale Valley, Radcliffe, be found who might find it difficult Rochdale Area to recover from a major flooding incident. The rapid expansion of 100 to 500 Swinton and Eccles, Bradford industrial development in the late and Deansgate, Ramsbottom, 19th century and its subsequent Rural Areas, Bury, South Oldham/ decline in the late 20th century , Bolton left the Irwell Catchment with an unfortunate legacy. Many of the 50 to 100 North Oldham, Whitefield, Kearsley/ watercourses are heavily modified Kersal, Milnrow/ Shaw, Middleton/ and riverside development has resulted in approximately 5,000 properties at risk from main river 25 to 50 None flooding. There are over 1300 culverts in the catchment, the Table 2. Critical infrastructure at risk: condition and capacity of which has a significant effect on flood risk. 2.5km of Motorway, 8.5km of A-roads, 10 sections of railway line, 8 Radcliffe, Ramsbottom, Rochdale Police Stations, 3 Fire/Ambulance Stations, 176 Gas/Electricity assets, and Salford have areas where there 1 Telephone Exchange, 5 Works, 1 Water Treatment is significant flood risk to people Plant, 41 Schools, 21 Care Homes, 1 Hospital, 59 Health Centres. as either the depth of flooding or the velocity of the water is enough to pose a serious hazard in a significant flood event.

The map overleaf shows where the properties are at risk of flooding in a 1% annual probability event.

We recognise the potential risk from surface water and sewer flooding. Further studies, following on from the CFMP, will be carried out to quantify this potential risk.

Salford Quays

Environment Agency Irwell Catchment Flood Management Plan 7 Map 2 Risk to property across catchment for a 1% annual probability fluvial event (undefended)

How we currently manage the risk in the catchment

The Irwell Catchment contains an off-line flood storage basin Activities that reduce the probability a large amount of historic and with a capacity of 650,000m3 and of flooding include: more recently constructed flood provides protection for a 1.3% • Maintaining and improving defences. Some small local Annual Probability Event (APE). existing flood defences, structures flood embankments protecting • Construction of flood defences and watercourses. The catchment agricultural land are also evident, in Ramsbottom, Rochdale and has over 40km of raised as are mill walls and industrial Littleborough provide design defences and 1,300 culverts. structures close to rivers that were protection for a 1% event. The Environment Agency has to not constructed to act as flood inspect and maintain a significant defences. In addition to these engineering proportion of these structures, but schemes, other flood risk Recent schemes have benefited the many are owned by third parties. management activities are carried following communities as follows: out in the catchment. These include • Enforcement where riparian • The construction in Salford of activities that help to reduce the owners and others carry out the River Irwell Flood Control probability of flooding, and those work detrimental to flood risk, or Scheme. The scheme consists of that address the consequences of neglect their responsibilities. flood walls, embankments, and flooding.

8 Environment Agency Irwell Catchment Flood Management Plan The impact of climate change and future flood risk

• Identifying and promoting new In the future, flooding will be We estimate that by 2100 flood alleviation schemes or influenced by climate change, approximately 10,000 properties studies where appropriate, such changes in land use (for example in the Irwell CFMP area could be at as in Manchester City Centre urban development) and rural risk of fluvial flooding. This is a 30% and in Salford where a second land management. In the Irwell increase compared to the current flood alleviation basin has been catchment, sensitivity testing number. Flood levels are expected proposed. There is also strategy revealed that climate change has the to increase by up to 1m at Salford, work ongoing in Ramsbottom, greatest impact on flood risk, with by 0.9m at Radcliffe and 0.5m in Radcliffe, Rossendale and for the urbanisation, having a smaller effect. Rochdale by 2100. One additional Irk and Medlock. The catchment is not very sensitive environmental site is very close to to land use change. Whilst we do not the predicted future flood extent • Working with local authorities to know exactly what will happen in the as are three further heritage sites, influence the location, layout and future the key trends are: these may be at risk of flooding design of new and redeveloped in the future. The flood depth and property and ensuring that only • More frequent and intense extent of flooding is expected to appropriate development is storms causing more widespread increase slightly at the sites in the allowed on the floodplain through flooding from drainage systems current 1% flood extent. the application of Planning Policy and some rivers. Statement 25 (PPS25). Figure 2 shows the shows the • Wetter winters increasing the difference between current and Activities that reduce the likelihood of large-scale flooding. future flood risk for a 1% annual consequences of flooding include: The future scenarios used in the probability event at key areas in the • Flood risk mapping, Irwell CFMP were: catchment (new data used where understanding where flooding is available). • A 20% increase in peak flow in likely to occur. all watercourses. The predicted Following on from the CFMP • Operation of floodline and flood increase in flow can affect the organisations need to work together warning services to over 8000 frequency, timing, scale of to investigate flood risk from other properties in six areas of the Irwell flooding and the flood levels. sources (e.g. surface water and catchment. sewer flooding) in more detail. • Increased urbanisation, up to 12%. • Providing flood incident management. Figure 2 Current and future (2100) flood risk to property from a 1% annual • Promoting awareness of probability river flood, taking into account current flood defences. flooding so that organisations,

communities and individuals are 3000 aware of the risk and are prepared in case they need to take action in 2500

time of flood. 2000

• Promoting resilience and 1500 resistance measures for those properties already in the 1000

floodplain. 500 Number of Properties at Flood Risk at Properties Number of

0 Bolton Bury * Salford Radcliffe ** Whitefield Ramsbottom Rural Areas Rochdale Area Kearsley/Kersal * Estimate from 0.5% flood outline ** North Oldham Swinton & EcclesMilnrow & Shaw Rossendale Valley ** Estimate from flood zone 2 Manchester City Centre ** Bradford & DeansgateMiddleton & Chadderton ** South Oldham & Droylsden Current Future

Environment Agency Irwell Catchment Flood Management Plan 9 Future direction for flood risk management

Approaches in each sub-area

We have divided the Irwell and raising defences. This is why This document does set out our CFMP area into ten distinct sub- we have to look catchment wide at policies for managing flood risk, areas that have similar physical how we direct effort and resources recognising the constraints that characteristics, sources of flooding to ensure sustainable solutions. do exist. Our future direction for and levels of risk. These sub- We have assessed what will be managing flood risk is expressed areas will allow us and the key the most sustainable approach by applying one of our six standard stakeholders to promote flood to managing flood risk in each policy options to that sub area. To risk management approaches, sub-area. This is presented in the select the most appropriate policy, policies and actions that are most following sections and they outline: the plan has considered how social, appropriate in that area to deliver economic and environmental the various Government and • The key issues in that area. objectives are affected by flood risk regional strategies, in particular the • The vision and preferred policy. management activities under each Making Space for Water strategy. In policy option. The six policy options the face of increasing risk, it often • The proposed actions to are explained on page 11. is not sustainable to keep building implement the policy.

Map 3 Sub-areas

10 Environment Agency Irwell Catchment Flood Management Plan Table 3 Policy options ➜ Policy 1 Areas of little or no flood risk where we will continue to monitor and advise This policy will tend to be applied in those areas where there are very few properties at risk of flooding. It reflects a commitment to work with the natural flood processes as far as possible.

➜ Policy 2 Areas of low to moderate flood risk where we can generally reduce existing flood risk management actions This policy will tend to be applied where the overall level of risk to people and property is low to moderate. It may no longer be value for money to focus on continuing current levels of maintenance of existing defences if we can use resources to reduce risk where there are more people at higher risk. We would therefore review the flood risk management actions being taken so that they are proportionate to the level of risk.

➜ Policy 3 Areas of low to moderate flood risk where we are generally managing existing flood risk effectively This policy will tend to be applied where the risks are currently appropriately managed and where the risk of flooding is not expected to increase significantly in the future. However, we keep our approach under review, looking for improvements and responding to new challenges or information as they emerge. We may review our approach to managing flood defences and other flood risk management actions, to ensure that we are managing efficiently and taking the best approach to managing flood risk in the longer term.

➜ Policy 4 Areas of low, moderate or high flood risk where we are already managing the flood risk effectively but where we may need to take further actions to keep pace with climate change This policy will tend to be applied where the risks are currently deemed to be appropriately-managed, but where the risk of flooding is expected to significantly rise in the future. In this case we would need to do more in the future to contain what would otherwise be increasing risk. Taking further action to reduce risk will require further appraisal to assess whether there are socially and environmentally sustainable, technically viable and economically justified options.

➜ Policy 5 Areas of moderate to high flood risk where we can generally take further action to reduce flood risk This policy will tend to be applied to those areas where the case for further action to reduce flood risk is most compelling, for example where there are many people at high risk, or where changes in the environment have already increased risk. Taking further action to reduce risk will require additional appraisal to assess whether there are socially and environmentally sustainable, technically viable and economically justified options.

➜ Policy 6 Areas of low to moderate flood risk where we will take action with others to store water or manage run-off in locations that provide overall flood risk reduction or environmental benefits This policy will tend to be applied where there may be opportunities in some locations to reduce flood risk locally or more widely in a catchment by storing water or managing run-off. The policy has been applied to an area (where the potential to apply the policy exists), but would only be implemented in specific locations within the area, after more detailed appraisal and consultation.

Environment Agency Irwell Catchment Flood Management Plan 11 Sub-area 1

Manchester City Centre to Irlam

Our key partners are: Flood maps indicate there are risk in this urban area and issues approximately 1,200 properties related to development. potentially at risk from river flooding in a 1% APE, although this does not currently indicate risk from The key messages Borough Council the canal. There are also potential flood risk issues with increased • Flood risk in the areas bounding Peel Ports development and surface water the Manchester Ship Canal is currently low, but this relies on British Waterways flooding. In the future, by 2100, we estimate 1,800 properties may be continued maintenance of the at risk in a 1% event. canal structures. Flood risk in the City Centre area is thought The issues in this Development adjacent to the Irwell, to be high, but this is based on such as the recent limited information. There are sub-area and planned Irwell City is no computer models of flood This is an urban area containing thought to be above likely flood flows in parts of the city centre the centre of Manchester and the levels, but potentially hundreds of and further work is required to areas that line the land along the commercial premises could be at evaluate the flood risk. Manchester Ship Canal including risk in an extreme flood. • In Manchester City centre much and . of the flood risk management It contains important cultural, work is concerned with the industrial and commercial The vision and continued maintenance of the developments. In the centre preferred policy ageing channel (walls) along the of Manchester, the Irwell was previously navigable, and has a Policy option 4: Areas of low, Irwell. canal-like character, with raised moderate or high flood risk where • Valuable commercial and retail walls creating a channel with a we are already managing the flood premises lines much of the river very large capacity to convey flows. risk effectively but where we may and canal, and there is potential Here the Rivers Irwell and Irk meet need to take further actions to keep for further development in the to form the Manchester Ship Canal pace with climate change. future - this could cause future that takes the flow downstream problems with surface water where the Medlock joins. Although Should flooding occur in the future, flooding/drainage. the canal is used for navigation, it potential damages would be high also plays a role in reducing flood due to the value of surrounding • Any future increase in flows from risk in Manchester and other areas. development. Therefore, a policy the Irwell catchment would affect The sluice structures that regulate to take further action to prevent the area and the Ship Canal, the Ship Canal were designed to flood risk increasing in the future therefore any future flood risk keep canal water levels relatively is justified. Initially this may be management activities further constant, and raised embankments achieved by working in partnership upstream are important. and walls create a channel with a with Peel Ports and with the City very large capacity to convey flows. Councils to better understand flood

12 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Undertake more detailed studies to identify current and future flood risk in Manchester City Centre, including formation of a steering group with representatives from partner organisations.

• Develop a flood risk strategy for the Central Manchester area (including the non-main sections of the River Irwell) to improve understanding of flood risk and identify future management needs.

• Continue to provide advice on development issues so as not to increase direct flood risk and/or surface runoff.

• Undertake more detailed studies to identify current and future flood risk from the Manchester Ship Canal.

• Explore options to manage future increases in flow.

River Medlock

Environment Agency Irwell Catchment Flood Management Plan 13 Sub-area 2

Salford, Swinton and Eccles

Our key partners are: In Salford New development has water levels in the future by up to been carefully designed to be one metre (Salford). Salford City Council resilient to flooding, and a Flood • Flood defences, including walls Protection Scheme involving a United Utilities and a storage basin, protect storage basin was completed in Salford from most floods, but a Landowners 2005. This basin successfully very large event could bypass or protected Salford from flooding in overtop some of these defences. January 2008. In the future, due to climate change, we estimate using • We provide a free flood warning The issues in this flood maps over 3,000 properties service to over 7000 homes and sub-area may be at risk in a 1% event. businesses in this area, however sign up to the service is low Salford is an urban area with which means that people may not a mixture of residential and The vision and be able to react in time to save commercial property. It is the possessions or leave the area. location of the largest historic flood preferred policy in the Irwell catchment in 1946, Policy option 5: Areas of moderate • Numerous sites have been when an estimated 5000 properties to high flood risk where we can identified for development, with were flooded. The area is a key site generally take further action to some of these covering a fairly for regeneration in the North West reduce flood risk. substantial area - this could and many properties are located in cause future problems with the floodplain of the River Irwell. Due to the high current and future surface water flooding/drainage. risks to property and infrastructure, In this policy area is the low high levels of community disruption • There are a significant number lying suburban area that drains a and risk to life if flooding occurred of culverts within the area. The number of small watercourses into (Salford), the policy is to take condition of the culverts and the the Manchester Ship Canal in the further action to reduce risk. This flood risk that they pose vary Swinton and Eccles area. will encompass an appraisal of the widely. Limited channel capacity increases the flood risk and The main cause of flood risk in various flood risk management the problem is accelerated by this area is insufficient channel options for the sub-area and may increased debris build up and capacity leading to flooding of small include making properties more sedimentation. watercourses or culvert blockages resistant and resilient to flood this combined with development events and through effective within the natural floodplain, planning and development control. increases surface water and sewer flooding. The key messages Flood maps indicate that this policy area has nearly 2,000 properties • Flood risk in area is high, with a at risk of flooding in a 1% APE, historic record of flooding (incl. although flood maps are currently sewer flooding) and thousands being revised in the Brook of properties located in the area. floodplain. Predicted increase in

14 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Continue to provide advice on development issues, and ensure inappropriate development does not take place in flood risk areas, so as not to increase direct flood risk and/or surface run-off.

• Develop a Flood Risk Management Study for the Swinton and Eccles areas as part of the wider Glaze catchment study to assess viable options to reduce flood risk.

• Identify routes of culverts and monitor their condition. Undertake a risk based assessment where the condition and hydraulic capacity is unknown. Consider remedial work such as debris screens and removal of culverts where appropriate.

• Further investigations into the potential for a second flood storage basin in Salford or upstream, or look at alternatives to reduce future flood risk.

• Promote the Flood Warning Service to local residents and businesses to increase the number of people receiving warnings. Look to improve flood forecasts and timing of warnings.

Irwell at Salford

Environment Agency Irwell Catchment Flood Management Plan 15 Sub-area 3

Kearsley to Kersal

Our key partners are: The issues in this shown that substantial upstream sub-area storage is required. There may be Salford City Council suitable land for this type of action in this sub-area. The policy is Bolton Metropolitan Borough The area has a variety of land therefore to take action with others Council uses including urban, agricultural, parkland and woodland areas. It to store water or manage runoff in United Utilities is an area containing important this area, to potentially reduce flood infrastructure such as part of the risk further downstream in Salford M60 motorway, sewage treatment and Manchester. works at Ringley Fold, railways and a prison at Hall Hill. The area has environmental and cultural The key messages importance, with two Special Sites • Flood risk in this area is currently of Scientific Interest (SSSIs) located low, with the exception of on the river banks. The risk from isolated sites. Predicted future fluvial flooding is low. Flood maps increase in water levels is low at indicate that 75 properties are at 0.3 metres. risk of flooding in a 1% event. It is estimated this will increase to • Ash Clough and Nob End SSSIs 150 by 2100 due to the effects of should be protected from any climate change. An environmental negative impacts from river and risk is present at Ringley Fold flood management, operations Sewage Treatment Works which, have been highlighted which are if flooded, could cause ecological likely to damage the SSSIs. damage to the river. • We are producing a strategy for the Lower Irwell to look into the The vision and feasibility of flood storage in this preferred policy area.

Policy option 6: Areas of low to moderate flood risk where we will take action with others to store water or manage run-off in locations that provide overall flood risk reduction or environmental benefits.

A review of potential measures to combat future increases in flood risk across the whole catchment has

16 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Develop a Flood Risk Management Strategy for the Lower Irwell. This will focus on possible ways of reducing flood risk in Salford.

• Identify potential storage areas (either natural floodplain storage or sites for storage basins) in this area.

• Continue to provide advice on development issues so as not to increase direct flood risk and/or surface run-off, including working with United Utilities to assess flood risk to sewage treatment works.

Ringley Old Bridge

Environment Agency Irwell Catchment Flood Management Plan 17 Sub-area 4

Middleton, Radcliffe & Milnrow

Our key partners are: flood defences (Radcliffe). Flooding and regeneration. Reducing sewer problems may be made worse by flooding will help improve water Bury MBC build-ups of gravel and debris, and quality within the Irk, and the lower culvert capacity issues. Around parts of the Irwell. Manchester City Council Milnrow and Shaw rapid run-off Rochdale MBC from the steep-sided catchment, flows through extensively modified The key messages Oldham MBC and constrained watercourses that can lead to flooding. There are also • Flood risk in this area is high, local landowners sewer-flooding problems identified at in some places the predicted United Utilities and Middleton, although increase in future water levels is the Crumpsall problems are remote around 0.8 metres. We need to County Council from the main watercourse and not better understand this level of thought to be linked to high river flood risk, and decide whether it levels in the Irk. should be managed differently. The issues in this Hydraulic models suggest that • Flood risk in this area is sub-area water levels in many areas are localised and in places it is sensitive to future changes in flow linked to historical development This sub-area consists of three that could increase flooding in the along the watercourse which separate urban areas much of it area. We estimate, by 2100, over included modifying the river by developed during the industrial 1,100 properties may be at risk of straightening and culverting. revolution. There are still industrial flooding in a 1% APE due to effects There are some existing defences. and commercial buildings in use of climate change. • Flood defences currently protect next to the rivers. The area extends Close Park in Radcliffe and from Manchester City Centre and commercial land at Pioneer follows the upstream The vision and Mill and from most through Cheetham Hill, Crumpsall, preferred policy floods, but a very large event Middleton and Chadderton. It could bypass these structures. includes the areas around Radcliffe Policy option 5: Areas of moderate Some of the defences are in poor on the River Irwell and around its to high flood risk where we can condition and it is uncertain confluence with the Roch. Included generally take further action to whether these will continue to also are Milnrow and Shaw in the reduce flood risk. protect properties as they fall upper part of the catchment on the into disrepair, or if flood risk , a significant tributary Current and future flood risk to increases in the future. of the . Within the area, property, infrastructure and the there is important infrastructure and environment are high. Levels of • The Irwell Flood Warning a number of recorded historic and community disruption and risk to Management Plan recommended environmentally sensitive locations. life in this area necessitates a policy that a Flood Warning System be to take further action to reduce risk. developed in the area. The main risk areas are at Radcliffe, This might include constructing new Blackford Bridge, Pioneer Mills, flood defences, improving current • Parts of this area will be Milnrow and Middleton. Flood maps structures or decrepit channels. redeveloped in the future, indicate there are over 850 properties Communities and properties need and may offer opportunities to at risk of flooding in a 1% APE, 400 to be made more resilient to flood reduce flood risk, for example, by of which are currently protected by events through effective planning restoring floodplain.

18 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Develop a Flood Risk Management Strategies for the Radcliffe area, for the River Beal, (as part of the River Roch) and for the River Irk (as part of a wider Central Manchester Strategy) to assess viable flood risk reduction options.

• Continue inspecting the condition of existing defences, investigating where appropriate local schemes to refurbish or improve defences where suitable.

• Identify and monitor culvert condition and undertake a risk-based assessment where the condition and hydraulic capacity is unknown; undertake remedial works where appropriate.

• Continue to provide advice on development issues so as not to increase direct flood risk and/or surface run-off.

River Beal natural channel

Environment Agency Irwell Catchment Flood Management Plan 19 Sub-area 5

Bury, Bolton and Ramsbottom

Our key partners are: In the sub-area, around 1,000 increase in the future due to properties are at risk of flooding in increased urban development. Bury Metropolitan Borough Council a 1% APE, mainly in Ramsbottom and Bury. In very large floods, areas Rossendale Borough Council of commercial and residential The key messages Bolton Metropolitan Borough property in Bury are at risk in the Council Redvales and Elton districts as well • Flood risk in this area is currently as Blackford Bridge Waste Water low, and limited to localised areas, Landowners Treatment Works. In Ramsbottom, but development of land adjacent a flood warning service is provided. to the watercourse can increase The main contributing factors to risk. Greater flows are predicted flood risk are channel capacity due to climate change. This could The issues in this problems, thought to be caused by cause future problems with surface sedimentation. Particular problem sub-area water flooding/drainage. areas are around culverts that This sub-area consists of three can block if debris is not cleared • Many of the raised defences separate mainly urban areas. Bolton regularly. In the future due to along the Irwell are believed to be centre and settlements on the climate change it is estimated in a poor condition, with concerns outskirts, along with the town of around 1,200 properties will be at such as broken bricks and bare Ramsbottom. risk in a 1% event by 2100. ground on the banks. There are many culverts, some in poor The areas are located in the centre of condition and some on minor the catchment where the gradient of The vision and the Irwell is flatter and surrounded tributaries. It is believed over 120 by moorland. Much of the area preferred policy properties are near enough to be grew rapidly during the Industrial affected by high flows or flooding Policy option 4: Areas of low, Revolution with the development resulting from blockages. moderate or high flood risk where of mill buildings and commercial we are already managing the flood • Flood risk in this area is currently and residential properties on the risk effectively but where we may managed with localised floodplain. Most of the watercourses need to take further actions to keep defences, but this relies on are heavily modified and contain a pace with climate change. continued monitoring of channel large number of culverts and weirs. capacity, sedimentation and The growth of urban areas, the need operation of existing defences. Bury does not have a history of to maintain channel capacities and significant flooding but Ramsbottom value of surrounding land justifies a • Consideration should be given does have a history of flooding, and policy to take further action to sustain to long-term gravel/sediment in 2000 a scheme was constructed current levels of flood risk in the management strategy for this and which defends around 115 low lying future. This may include development neighbouring areas with the aim properties from flooding. In Bolton, and planning measures, such as of finding a more sustainable the principal sources of flood risk identifying areas of floodplain approach. are from the abundance of culverts storage, in preference to constructing on ordinary watercourses and the new defences and long-term gravel/ • In Bury, future increase in flows capacity of the sewerage system. sediment management strategies could potentially affect Nuttall Fluvial flooding along the principal where it is critical channel capacity Park, where there is a risk of rivers of the Croal and Tonge has not is maintained. We will look to environmental due to been identified as a significant issue. reduce flood risk from smaller the location of the wastewater watercourses that may otherwise infrastructure.

20 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Undertake studies in the Ramsbottom, Bolton and Bury areas to assess options to reduce future flood risk.

• Consider identifying potential flood storage areas.

• Review Gravel Management Strategies (Upper Irwell and Roch) to identify how sustainable sediment management influences flood risk in Ramsbottom and alter maintenance strategies as appropriate.

• Continue localised investigation of flooding from small watercourses, such as Bessy Brook, to assess feasibility of defences and install where suitable.

• Continue to provide advice on development issues so as not to increase direct flood risk and/or surface run-off.

Ramsbottom Weir

Environment Agency Irwell Catchment Flood Management Plan 21 Sub-area 6

Rossendale Valley

Our key partners are: The issues in this valley sides, increases will be sub-area greater. We will take action to Rossendale Borough Council decrease flood risk, and to account for future increases in risk. Actions Local Landowners The towns in the Rossendale Valley have developed in narrow, might involve maintaining channel steep sided valleys adjacent to capacity by ensuring culverts the watercourse. They have a long and river-side walls are in good history of flooding from the river, condition, managing gravel where it urban drainage and from surface increases flood risk, and increasing run-off from fields and moorlands. flood resilience. Small settlements like , Chatterton, Stubbins and generally have little protection from The key messages floods. The area has many culverts • Flood risk in this area is high, on the main river, some of these there is a history of flooding and are collapsing or have low capacity. hundreds of properties located Build-up of gravel and debris in along the river in the narrow the river might increase flood valley of the Upper Irwell are at risk and gravel removal has been risk. undertaken historically. Flood maps show around 650 properties are at • There are few formal flood risk of flooding in a 1% APE and by defences, but much of the 2100 climate change is expected channel is walled and there are to increase this figure to 1,000 many culverts. Some of these properties. structures are in poor condition and future maintenance is essential; responsibility for The vision and these structures lies with the preferred policy landowners.

Policy option 5: Areas of moderate • As the towns are quite high in the to high flood risk where we can catchment, it is not possible to generally take further action to give flood warnings to all areas reduce flood risk. and where we do, we can only offer 2-3 hours warning of floods. Analysis of the water level at Floods can occur rapidly due Stubbins, where there is a relatively to the steep valleys and lack of wide floodplain, shows that climate natural floodplains. change could result in a small increase in water level. Further upstream, where the channel is more confined by walls and the

22 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Carry out a study of flood risk in the Upper Irwell area to identify possible ways of reducing flood risk. This might include removing old walls and culverts where possible, or identify natural floodplains that could be used for flood storage. It should also include a review of how gravel affects flood risk and how its management could be changed in the future for flood risk and environmental gain.

• Look at culvert condition in urban areas, and undertake an assessment of risk where the condition and hydraulic capacity is unknown; carry out remedial works such as redesign or removal where possible for flood risk and environmental gain.

• Continue to provide advice on development issues so as not to increase direct flood risk and/or surface run-off.

Irwell upper reaches

Environment Agency Irwell Catchment Flood Management Plan 23 Sub-area 7

Rural Areas

Our key partners are: The issues in this The vision and

Rossendale Borough Council sub-area preferred policy

Blackburn with Borough Located in the middle and north Policy option 6: Areas of low to Council of the Irwell catchment, this area moderate flood risk where we will is mostly upland, surrounding the take action with others to store Borough Council steep sided valleys of the Upper water or manage run-off in locations Irwell catchment and Rossendale that provide overall flood risk Bolton Metropolitan Borough Valley. This area contains the reduction or environmental benefits. Council headwaters of the Roch and Natural land cover in this area is Rochdale Metropolitan Borough Spodden and the principal rivers likely to have been changed by Council that drain the Croal catchment. grazing, peatland management and It is sparsely populated with the deforestation. These changes could Edge Forest exception of some villages and contribute to increased run-off. Land historic industrial sites. The current Natural England management could potentially play level of flood risk to people and a key role in reducing local flood risk Red Rose Forest property is low, because of the low by reducing rates of runoff, and may density of development. Local landowners have a benefit further downstream The headwaters are characterised in the more urbanised Rossendale by moorland and large reservoirs Valley, Croal valley around Bolton such as Delph, Jumbles, and the Roch valley around and Watergrove Littleborough and Rochdale. that regulate flows in the main tributaries. The key messages There is another source of flooding is surface water run-off from steep • Flood risk in this area is low, due to fields and moorland, especially low population and small streams. after heavy rainfall. There are frequent but isolated floods on • Actions to reduce run-off from brooks and streams, and some the upper catchment could risk to individual properties from have local benefits and provide small tributaries with blocked some help to reduce peak flows culverts. The rural land use means downstream. that flooding does not create major • Part of this area near Rochdale risks. Approximately 240 properties is a site of international have a 1% chance of flooding each environmental importance and year over this large rural sub-area. it is designated as a Sites of This is expected to increase to Special Scientific Interest (SSSI) around 275 by 2100 due to climate on ecological and geological change. grounds, which may constrain flood risk actions.

24 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Explore ways of achieving land management change to reduce run-off from the upper catchment, for example through blocking of moorland grips, creation of storage ponds, targeted woodland creation.

• Part of this rural area is a site of international environmental importance and it is designated as a SSSI on ecological and geological grounds, which may constrain flood risk actions.

Belmont Reservoir

Environment Agency Irwell Catchment Flood Management Plan 25 Sub-area 8

Bradford and Deansgate

Our key partners are: The issues in this The vision and

Manchester City Council sub-area preferred policy

Landowners This is an urban area containing Policy option 5: Areas of moderate areas of high value commercial and to high flood risk where we can Peel Ports residential properties, including generally take further action to the current BBC building on Oxford reduce flood risk. British Waterways Road and several listed buildings The high value of development in along Deansgate. The this area justifies a policy to take is highly modified in this area with further action to reduce flood risk, a low gradient that increases the initially by increasing understanding potential for sediment and debris of the flood risks. to build up in the channel. The area contains no functional floodplain as the channel is deepened and the areas prone to flooding are The key messages paved and artificially drained. • Historic flood risk in this area There is no detailed hydraulic is thought to be low, but this is model for the Medlock, therefore based on limited information as the scale of flood risk is not well there are no computer models understood, but currently we of flood flows in this part of the estimate using flood maps around catchment. 150 properties are thought to be at risk in a 1% event. Climate change • In the Bradford area, there is is estimated to increase this to 350 some large residential and by 2100. Just downstream of this commercial development area, the Medlock discharges into adjacent to the new City of the Manchester Ship Canal via a Manchester Stadium. Some number of syphons and sluices. The proposed developments are Environment Agency liaises with located close to the watercourse - the Peel Ports over the operation of this could cause future problems the sluices to ensure the Medlock with surface water flooding/ can discharge freely during flood drainage. events. • Many walls along the Medlock are believed to be in poor condition, or are not formal defences. Approximately 2% of walls contain gaps either caused by deterioration or breaches.

26 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Investigate conveyance capacity, identify and mitigate flood risk in Tue Brook and Deys Brook.

• Establish policies within Local Development Frameworks that work towards long term protection and re-creation of watercourse corridors / floodplain through sustainable land use management.

• Encourage Sustainable Drainage Systems (SuDS) as a means of reducing overall flood risk and controlling pollution from urban run-off.

River Medlock near UMIST

Environment Agency Irwell Catchment Flood Management Plan 27 Sub-area 9

Heywood, Whitefield and South Oldham

Our key partners are: hydraulic model for the Medlock; The key messages therefore the scale of flood risk is Oldham Metropolitan Borough not well understood. • Flood risk in the area is low as Council development is mostly situated Heywood and Whitefield are not above the floodplain and there Borough Council thought to be at significant risk are few formal defences. from fluvial flooding but much of Bury Metropolitan Borough Council the area is urbanised so properties • On the Medlock there are no Rochdale Metropolitan Borough could be at risk if culverts become computer models of flood flows Council blocked or collapse. United Utilities so there is some uncertainty has identified a number of potential about the number of properties sewer flooding sites within the at risk. Many of the floodwalls Oldham and areas. along the Medlock are believed The issues in this to be in poor condition and sub-area there are issues with sediment The vision and deposition. This sub-area features three geographically separate areas with preferred policy • There are also over 100 culverts in the areas, for which the similar flood risk characteristics. Policy option 3: Areas of low to condition and capacity are There are urban areas in Droylsden, moderate flood risk where we are unknown, these could pose a Openshaw, Failsworth and Oldham generally managing existing flood flooding risk these and may but also semi-rural land and open risk effectively. space around the Medlock, and require future maintenance. in the east of the area. Whitefield A policy to continue with existing or • Parts of the area on the River sits to the south of the Roch/Irwell alternative actions to manage flood Roch may be included in a wider confluence. The land is generally risk at the current level was chosen study of flood risk on that river. flat but elevated above the river. as current management actions The area contains some important appear to be adequate and it is not road links including the M66 and thought that future climate change M62/M60 motorways. Heywood is scenarios will increase the risk located on the River Roch, between from fluvial flooding significantly. Rochdale and Bury. Options to reduce run-off and control development may present Flood maps identify approximately the most sustainable options to 500 properties are at risk in a ensure no increase in flood risk. 1% APE most of which are in the The proximity of a large number South Oldham to Droylsden area. of properties to culverts justifies We estimate this could increase to continuing the development over 600 properties in the future of a prioritised inspection and due to climate change. There is no maintenance regime.

28 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Develop hydraulic models for the Medlock to increase understanding and extent of flood risk.

• Carry out a study of flood risk on the River Roch to better understand the risk now and in the future, and identify possible management options.

• Develop a Flood Risk Management Strategy for the Medlock, as part of a wider Central Manchester Strategy, to increase understanding and extent of flood risk and suggest possible management options.

• Continue to provide advice on development issues so as not to increase direct flood risk and/or surface run-off.

• Identify and monitor culvert condition and undertake a risk-based assessment where the condition and hydraulic capacity is unknown; remedial works where appropriate.

Parr Brook - Whitefield

Environment Agency Irwell Catchment Flood Management Plan 29 Sub-area 10

North Oldham, Rochdale, Whitworth and Littleborough

Our key partners are: in 2005, to reduce flood risk in with up to a half metre rise at the Rochdale and Littleborough. We confluence of the Oldham Metropolitan Borough estimate over 750 properties have and Roch. The identified future Council a 1% chance of flooding each year. increase in risk supports a policy to In future, by 2100, we estimate continue to do more to ensure that Rochdale Metropolitan Borough this will increase to over 1,100 flood risk does not increase in the Council properties due to climate change. future. Rossendale Borough Council Culverts and bridges that obstruct high flows, as well as build up of Local landowners gravel at some points in the river, The key messages United Utilities increase flood risk. • Flood risk is high in the Rochdale area and combinations of high The vision and river levels and surface water run- off have been known to cause The issues in this preferred policy sub-area flooding. Risk in other parts of Policy option 4: Areas of low, the sub-area is relatively low In the north of this sub-area is moderate or high flood risk where compared to other areas of the Rochdale and Littleborough, which we are already managing the flood Irwell catchment. sit to the upstream end of the River risk effectively but where we may • Maintenance of culverts on the Roch, and Whitworth that lies along need to take further actions to keep relatively small watercourses is the River Spodden. The south of pace with climate change. important to prevent any increase this sub-area covers the wider Irk in flood risk. catchment, comprising urban areas There are over 80 culverts in the to the north and west of Oldham, area, a quarter of which have been • Limitations of the wider drainage and to the north of Middleton, and assessed as needing remedial and sewerage system have links contains small tributaries of the works in the short to medium term. to flood risk in some areas. River Irk and . The current level of fluvial flood risk is relatively low, and does not • There are plans to re-develop In the south of the area the risk increase significantly with climate some parts of Rochdale town of fluvial flooding is lower than in change. However the risk from centre, including areas that neighbouring areas, but some areas sewer flooding appears to be a are protected by floodwalls have a history of sewer flooding problem in certain areas (such as constructed in 2005. and there are many culverts that Failsworth and Moston). This could • It is uncertain whether recent may need future maintenance. The be addressed through improved defences will protect properties town centre of Rochdale sits within integrated drainage. There are a if flood risk does increase in the a broad low-lying valley with steep number of areas that have been future, and the level of protection sides and consequently, it crosses a highlighted for future development, the floodwalls offer will need to corridor of high flood risk. The River including in the city centre along be reviewed as part of a study on Roch capital scheme was completed the course of the Roch. This area the River Roch. is sensitive to increases in flow,

30 Environment Agency Irwell Catchment Flood Management Plan Proposed actions to implement the preferred policy

The essential actions to achieve our policy aim are listed below:

• Continue to provide advice on development issues so as not to increase direct flood risk and/or surface runoff.

• Continue to investigate causes of sewer flooding (including links to river processes) and the standards of service in relation to problems, followed by appropriate remedial works where necessary.

• Look at culvert condition and undertake an assessment of risk where the condition and hydraulic capacity is unknown and carry out remedial works such as redesign or removal, where possible, for flood risk and environmental gain.

• Carry out a study of flood risk on the River Roch (on a sub-catchment scale) to better understand the future flood risk, and identify possible management options. This may investigate a range of issues relating to recent flooding including reassessing standards of protection, gravel management and the potential for storage basins and local defences.

River Roch at Rochdale

Environment Agency Irwell Catchment Flood Management Plan 31 Map of CFMP policies

32 Environment Agency Irwell Catchment Flood Management Plan

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