Lower Mole Flood Alleviation Scheme revised shortlisted options

Closed 6 Nov 2024

Opened 15 Aug 2024

Contact

Lower Mole Project Team

03708 506 506

fasproject.lowermole@environment-agency.gov.uk

Results updated 29 Jan 2025

Introduction

The Lower Mole Flood Alleviation Scheme protects around 1,300 homes and businesses in the area from flooding. The Scheme was constructed in response to the 1968 flood event which saw several thousand properties along the River Mole subject to flooding. The Scheme is now reaching the end of its design life and needs to be refurbished to maintain its standard of flood protection into the future and to ensure it is the best scheme for the environment, people and wildlife. There are six main sluice structures along the length of the Scheme and we need to make decisions on their future. Following on from engagement with the community and other stakeholders in 2019 to share initial concepts and in 2021 to gather feedback on an original options shortlist, we created a revised shortlist of options to consider what the consultees had told us. Throughout the project the content of the Government Flood and Coastal Risk Management appraisal guidance has been used to steer and guide the project. The details of that guidance can be found here https://www.gov.uk/guidance/flood-and-coastal-erosion-risk-management-appraisal-guidance/8-compare-and-select-the-preferred-option 

In 2024, we consulted and engaged the community on the revised shortlist to hear their views on the options named as Red, Blue, Pink and Orange (the national economically preferred option) to help us make the final decision on the preferred option for the Scheme. 

How we ran the consultation

The consultation was open for 12 weeks from 15 August to midnight 6 November 2024. We consulted stakeholders using our online consultation tool, Citizen Space. We also provided paper copies on request. Before the consultation we updated our project website on Engagement HQ https://engageenvironmentagency.uk.engagementhq.com/hub-page/lower-mole-flood-alleviation-scheme with information about each option as well as the wider information about the Scheme and promoting the forthcoming consultation.  

We also promoted the consultation on our Environment Agency Southeast X account and via partners on their social media accounts. We issued a press release to local media and posted articles on BBC Surrey and the Elmbridge Borough Council website. We sent posters to community spaces, including libraries, council buildings and village halls located in and around the Scheme extent. We carried out two mail drops to residents geographically closest to the scheme, the first on the 6 September 2024 and the second on 28 October 2024. We sent update emails throughout the year leading up to and during the consultation to partners, councils, the local MP, local Councillors and stakeholders on our mailing list. We provided updates in the River Mole Catchment Partnership newsletter and spoke about the options and consultation at one of their regular meetings. During the consultation period, we ran 3 public drop in events at different locations across the Scheme from East Molesey to Esher.  

The Scheme covers a large area. We recognised that not all parts of the river and the different sluice structures would be of interest to everyone viewing or responding to the consultation. Therefore, we created sections within the consultation based on the geographical locations of the existing sluice structures and the surrounding parts of the river they are located on. This meant that consultees had the choice to answer any specific sections or questions that were most applicable to them. For those interested in the scheme as a whole, there was also the opportunity for respondents to answer all questions within the consultation. 

We received 203 responses in total, of which 197 were individual responses, 4 responded on behalf of an organisation or group, 2 responded as other. Respondents told us that the main three ways they found out about the consultation were from us directly, from one of our posters or fliers and via social media.  

Summary of key findings

We asked you to rank the options Red, Blue, Pink and Orange (the national economically preferred option) in order of the one you most prefer to the one you least prefer.  

  • Option Red received 128 votes, which equates to 63% of votes. 
  • Option Orange received 56 votes, which equates to 28% of votes 
  • Option Blue received 14 votes, which equates to 7% of votes. 
  • Option Pink received 5 votes, which equates to 2% of votes. 

These figures are based on consultees first choice option only. The percentage of votes has been calculated using these figures as a proportion of the total number of responses. Asking you to also rank your second, third and fourth option preferences allowed us to collect valuable data for the long-term project, offering insights that enhance future project planning and deepen our understanding of the scheme in the context of all our stakeholders. Having an idea of what consultees selected as their other choices and in what order helps us understand what is, and what is not, important to you across the scheme. Also, if two options happened to receive the same amount of first choice votes, we could then use the broader data collected to assist in understanding stakeholder preference and which option for the project to aim to take forward. 

From the open text box, it was possible to see some common themes on how and why consultees had chosen to rank the options. 

  • 106 consultees ranked the options because of reasons related to water levels, 91 of the 106 voted for option Red. 
  • 53 consultees ranked the options because of reasons related to biodiversity impacts, 49 of the 53 voted for option Red. 
  • 45 consultees ranked the options because of reasons related to amenity impacts, 43 of the 45 voted for option Red.  
  • 43 consultees ranked the options because of reasons related to atheistic, 40 of the 43 voted for option Red. 
  • 39 consultees ranked the options because of reasons related to flood risk, 31 of the 39 voted for option Red. 

We asked if you would be interested in attending one of our guided tours around the Lower Mole to find out more about the work. 100 consultees said yes and we are currently arranging the tours for Spring 2025. We will be in touch with those who expressed interest.  

We asked you whether there were any issues that stop you using the river corridor for informal recreation and exercise. Of the 144 consultees who answered this question 52 of you responded that there were issues, which mainly focused on improving amenities. Using the open text box 30 of the 52 consultees raised issues around currently limited access to and along the river and footpaths due to gates and fencing, with requests to provide a continuous path for walking on riverside. A total of 32 consultees said there are no issues currently impacting their use of the river area.  

We asked you to propose ideas for improvements to the river corridor for amenity, leisure and recreation purposes. We received 145 responses with 58 of these responses referring to amenity improvements and with 20 of the 58 responses suggesting improvements to active travel routes, especially footpaths, along the riverside to provide continuous and connected routes. Both biodiversity improvements and water levels were mentioned in 19 responses. Requests were made to regularly reduce the number of invasive species such as Pennywort, Knotweed or Himalayan balsam and to control the mink population as they endangered other wildlife. 

We asked you if there is anything else important to you about the rivers, what they mean to you and how you use them. From the 159 responses we received, amenity impacts were raised 32 times. These consultees expressed concerns over reduced opportunities for water recreation due to lower water levels under certain options and limited safety for children. 

We know water levels are really important to the community. We asked two questions about water levels at Molember Sluice and Viaduct Sluice. Of the 153 who responded for Molember Sluice, 104 (51%) of you indicated that they strongly favour retaining existing water levels at Molember Sluice, compared to 23 (11%) who favoured lower water levels. Of the 135 who responded for Viaduct Sluice, 80 (39%) of you indicated that you strongly favour retaining existing water levels, compared to 26 (12%) in favour of lower water levels. 

We will explore the possibilities of providing permissive access along the west bank of the river around Island Barn Sluice. We asked if permissive paths along the west bank of the river around Island Barn Sluice would be useful to the community. 74 (36%) of you said yes, 31 (15%) people said no, this question was not answered by 69 (34%) consultees. 

When asked about the permissive path around Island Barn Sluice, 74 consultees were supportive. 52 responses relating to amenity improvements. 48 of the 52 responses stating they will use the new path and that it will improve access to the river for walkers and boats, providing new opportunities to engage with nature and make walking in this area easier and more pleasant.  

A total of 31 consultees said that the permissive path around Island Barn Sluice would not be useful and 10 said they would not use the path, that it would not provide any benefit because they already have sufficient access to the river, or they do not frequent this area in general. 

We asked you if there were any specific features you would like to see along this route: 

  • 37 consultees asked for seating areas 
  • 34 consultees asked for an accessible surface 
  • 22 consultees asked for information boards 
  • 22 consultees asked for “other” 
  • 88 consultees did not answer this question  

We asked you to select the measures you would like to see to help mitigate access for lower water levels upstream of Viaduct: 

  • 68 consultees said they would like steps/ramps for foot access  
  • 65 consultees said they would like planting/screening 
  • 46 consultees said they would like viewing areas 
  • 41 consultees said they would like boat ramps  
  • 89 consultees did not answer this question  

 Next steps

The full analysis report from the consultation which will contain more detail on the responses received will be made available by April 2025. The responses and feedback from our consultation will help us to select the final option for the Scheme. We are aiming to reach a decision on which option we are seeking to take forward during Spring 2025. 

We thank you for giving us your views. We will continue to listen to your feedback to help refine the direction of the project and future designs. If you would like to follow up on your response or points made within this document, in more detail, please contact us at fasproject.lowermole@environment-agency.gov.uk. 

Published responses

View submitted responses where consent has been given to publish the response.

Overview

The Lower Mole Flood Alleviation Scheme protects around 1,300 homes and businesses in the area from flooding. It was designed to reduce the risk of flooding in the lower reaches of the River Mole catchment following a significant flood event in September 1968. Construction of the scheme took several years and was completed in the 1980s.

The Scheme covers the stretch of the River Mole from Hersham up to the River Thames. This also includes the River Ember, an engineered channel created as part of the flood scheme, along with side channels at Royal Mills and the Ember Loop. The enlarged river channel provides additional capacity for high flows in the river during periods of prolonged and heavy rainfall. The sluice gates regulate water levels under normal circumstances but are opened during times of high river flows to allow water to pass to the Thames as quickly as possible.

The Scheme is now reaching the end of its design life and needs to be refurbished to maintain its standard of flood protection and to ensure it is the best scheme for the environment, people and wildlife. There are six main sluice gates and we need to make decisions on their future.

A map showing the whole Lower Mole Flood Alleviation area. There are multiple black river lines curving across a landscape from top right to bottom left. There are six bright green dots along the river from top right to the middle of the picture showing the six sluice gates structures. There is a purple dot which represents Albany Bridge. There are red and green lines across the map depicting roads and a few green areas. There is a blue semicircle in the top right (north east) which is a reservoir.

A Map showing the Rivers Mole and Ember, black line, and where the six main sluice gates, bright green dots, are located along the rivers to form the Lower Mole Flood Alleviation Scheme. Source: Environment Agency.

Why your views matter

In 2019, we engaged with stakeholders and the community on our initial options and heard your views around proposed changes to existing water levels. As a result of that feedback, we ran sessions with the community on how the scheme currently works and how we operate the sluice gates. Following this, we began work to better understand the dynamics of the river in more detail to help inform further investigations and designs. This work included bathymetric surveys, biodiversity net gain reviews, bat surveys, fish and invertebrates surveys.

In 2021, we shared a short list of options with the community. This was only carried out through online engagement due to Covid 19 restrictions. Using this feedback, we carried out additional work that included further modelling and several studies carried out by our engineers. This modelling work was key in ensuring that the updated designs would not increase flood risk. After completing all this work, we have created a revised shortlist of options.

For all flood risk management schemes, we follow funding rules set by the Government. We can attract funding for schemes through Grant in Aid (GiA) and other sources. For this Scheme the costs of all the options exceed the maximum amount of funding we can attract through GiA. This means that additional funding would need to come from external sources. This could come from Local Authorities, partners, businesses and the community. All of the options identified as part of the appraisal work will require additional partnership funding to deliver them.

We consider the cost and benefits of each option, using the decision rules set out in the appraisal guidance. We have also reassessed the changes in water levels, environmental benefits, cost, carbon footprint and maintenance implications, for each option.

Following the process, we have identified the national economically preferred option. Delivery of Options Red, Blue and Pink will require a greater proportion of additional funding. You can find more detail about the national economically preferred option on the whole scheme, funding and rating the options page and in the Government appraisal guidance links below.

The new revised shortlisted options

Option Purple - Do minimum to the Lower Mole Scheme

A purple rectangle demonstrating the colour of the option

We would only carry out reactive maintenance and repairs as the structures gradually failed. There would be similar levels of plant and animal habitat along and in the river. The water levels would remain similar to the current situation.

Option Red - Maintain the current water levels and habitat throughout the Lower Mole Scheme

A red rectangle demonstrating the colour of the option

We will keep the gates at Island Barn and Viaduct. There will be a combination of gates and fixed weirs at Molember. Plant and animal habitat along and in the river will not change.

Option Blue - Reduce changes in the water level and increase habitat by using fixed weirs and building a rock ramp

A blue rectangle demonstrating the colour of the option

We will keep the gates at Island Barn, replace the gates with fixed weirs at Molember. We will also remove the gates at Viaduct and build a new rock ramp upstream. There could be small increases in plant and animal habitat along and in the river.

Option Pink - Reduce changes in the water level and increase habitat by building two rock ramps

A pink rectangle demonstrating the colour of the option

We will keep the gates at Island Barn. We will also remove the gates at Molember and Viaduct and build new rock ramps upstream of both structures. There could be small increases to plant and animal habitat along and in the river.

Option Orange (national economically preferred option) - Reduce the water levels and significantly increase habitat

An orange rectangle demonstrating the colour of the option

We will keep the gates at Island Barn. We will also remove the gates at Molember and Viaduct. The river would start to become a more natural environment. There would be increases to plant and animal habitat along and in the river for at least 2km upstream of the scheme.

Your views on the Options Red, Blue, Pink and Orange are vital throughout the consultation period to help us make the final decision. The full shortlist includes Option Yellow ‘Do nothing' which is a requirement of the appraisal process to allow for the comparison of options. This helps us understand what the impact would be, if we did not deliver the project. Option Yellow is non-viable as it would lead to an unacceptable increase in flood risk if the gates at the main structures were not opened when river flows are high.

Option Purple ‘Do Minimum’ is also included in the full shortlist. This offers the same outcomes for the river in terms of water levels as Option Red, but at greater cost and in a less sustainable way with a higher carbon footprint. Therefore, although Option Purple is a viable option to maintain the current level of flood risk protection it is not considered an option we would seek to progress as the preferred option for the scheme.

This work over the last 5 years has been vital in helping us understand what is important to the communities of the River Mole and Ember. We thank you in advance for giving us your views. We will continue to listen to your feedback to help refine the direction of the project and future designs. Please share this with others in your community, so we may hear their views as well. Please click the online consultation link below to begin.

What happens next

Thank you for your views. We will now review them and update the Lower Mole community.

Events

Audiences

  • Recreational and commercial river users
  • Fishing clubs and representative associations
  • Businesses
  • Charities
  • NGOs
  • Members of the public
  • Elected representatives, including MPs
  • Local authorities
  • Land owners
  • Water companies
  • Community groups

Interests

  • Flood management
  • Fishing and boating
  • Water quality
  • Habitats and wildlife
  • Flood and coastal pages