The River Pinn Project information page

Closed 1 Oct 2019

Opened 10 Oct 2018


Updated June 2019

Welcome to the River Pinn project information page. This page provides background information to flooding along the River Pinn and a summary of our work to reduce the flood risk to homes, businesses and infrastructure along the river


Communities in the River Pinn catchment have experienced flooding several times, most recently in June 2016. The Environment Agency are working with Hillingdon and Harrow Councils as well as Thames Water to better understand the causes of this flooding and identify actions that could reduce the risk in the future.

The River Pinn catchment is in the west of the Greater London area. It flows through the London Boroughs of Harrow and Hillingdon before joining the Frays River in Uxbridge. The Pinn is joined by several smaller rivers along its length, including the Cannon Brook in Ruislip. It is also fed by numerous drainage outfalls which carry rainwater to the river. Generally the water flows in open earth channels, regularly passing through various bridges and culverts.

How you can help us:

  • champion the projects locally
  • help us identify additional sources of funding
  • tell us how you have been impacted by the River Pinn flooding
  • tell us about your local knowledge of the environment and flooding
  • if you have been affected by flooding from a sewer, then please report this to Thames Water using their sewer flooding questionnaire here
  • let us know if you have any questions or are part of a community group that would like to work with us

The project team’s contact details are at the right hand side of this page.


  • better understanding of the risk of flooding in the River Pinn and Cannon Brook catchments
  • collaborate with others to develop flood reduction proposals which maximise benefits for people and the environment
  • work with local communities to ensure they understand our proposals and what actions they can take to be more prepared for flooding
  • work with our partners to secure additional funding from other sources to help us deliver viable projects

Please understand that our proposals will not eliminate the risk of flooding altogether, only reduce it.

What is the latest?

In our last update in January 2019, we explained that we will be focusing our detailed design of options on the East Ruislip area first. We have now separated this project out from this page and it has its own separate webpage here:

The next detailed information we will be able to share with communities will be once we have completed our flood risk model update later this summer. Accurate information on how flooding occurs is key to developing solutions to reduce flood risk. An important part of this is developing a computer model which replicates where the water flows during rainfall. We have been working with our consultants AECOM to produce this model so that we can use this to test how potential options to reduce flooding will affect where the water goes.

We will need to utilise local knowledge to make sure that our model represents flooding as it is experienced on the ground.

This work started in March 2019 and will take up to 6 months to complete.

The River Pinn – individual project updates

As explained in our previous updates we have made a decision that the project will be progressed as 4 individual projects for the next steps. This is to enable us to focus on the specific areas, and progress each of them as soon as we are able to. The infographic below shows the different areas we are looking at and the potential options we are investigating.

For each of the study areas across the catchment we have determined which options or combination of options are most technically, financially and environmentally viable based on the information we have available at the moment.

The responses to our consultation told us people want to see more detail about how the options will affect them. The work we are starting now will continue to develop our understanding of how the options need to be designed to be most effective. We will continue to provide further information as it becomes available.

Individual project information:

Pinner and Hatch End

Our current preferred options for this area are a combination of:

  • embankments, walls and/or flood storage at Albury Drive
  • operational changes and control structure modifications to George V Reservoir (an existing flood storage area above George V Avenue)
  • natural flood management (NFM) in Pinner Wood

Following the model updates we will be able to look at the benefits of these options in more detail and refine our understanding of how much they will cost.

We will then need to find additional funding from other sources to enable us to progress this project any further.

West Ruislip

In the West Ruislip area, the options which we identified are not currently being taken forward as the costs are too high for the benefits that they would provide. Hillingdon Council have therefore created a long list of smaller-scale options. They will be reassessing their benefits and costs and are exploring taking forward alternative options in this area.

Following the model updates, the next step for the West Ruislip area is for us to work with Hillingdon, using all of the information we have gathered from communities, partners, and through the work we have done looking at options to establish the best way to take the project forward. We would like you to continue to work with Hillingdon and us to influence how this develops.

Even though we have not yet identified a solution which is financially, technically and economically viable, we have learnt a lot about the catchment and feel we are in a better place than we were when our project started. We would like you to continue to work with us to influence how this develops.

There has been a lot of concern and enquiries from residents relating to the silt build up in the Cannon Brook. We have reviewed all of the information we have been provided and discussed the issue with local experts. As a result we will be putting together a separate case study to outline our understanding of the silt processes in the catchment and any actions we think need to be taken to investigate it further. This document will be available on this page, and we will email our stakeholder list when it is published.

Lower Pinn

Our current preferred options for this area are a combination of:

  • embankments and/or walls - Dawes Road to Hillingdon Road, Uxbridge
  • embankments and/or walls – Church Road, Uxbridge
  • flood storage - south of Church Road, Uxbridge
  • embankments and/or walls - Zodiac Business Park, Yiewsley

Following the model updates we will be able to look at the benefits of these options in more detail and refine our understanding of how much they will cost.
We will then need to find additional funding from other sources to enable us to progress this project any further.

East Ruislip

We now have a separate page for the East Ruislip project here:

Regular watercourse maintenance:

Our regular watercourse maintenance work along the River Pinn and its tributaries continues throughout the year, and is carried out at the following intervals:

The River Pinn (main channel – shown in red on the below diagram) has 2 maintenance checks a year. This is broken into smaller sections of the river and staggered throughout the year. This consists of the field teams walking the channel and removing any large blockages and debris, they will then feedback accordingly about any issues.

The main tributaries of the River Pinn (shown in green on the below diagram) has a maintenance check every other month and one grass cut in the peak growth season to trim up the banks to maximise capacity and ensure conveyance.

The Cannon Brook (shown in blue on the below diagram) has a monthly maintenance check and a grass cut in the peak growth season.

If you see blockages in the channel which pose an immediate flood risk then this should be reported directly to our incident line on 0800 80 70 60

Working with communities:

During March 2018 over 180 people attended three public drop-in sessions in Ruislip, Pinner and Uxbridge. This was an opportunity for the public and other local stakeholders to look at our proposals for the River Pinn projects and discuss them with our colleagues and specialists. It also provided an opportunity for the public to tell us how flooding has impacted them in the past.

Our public consultation was available online for 6 weeks. We received over 120 responses from the public on our project plans. Please click here to view our consultation response report.

We will continue to gather the views and knowledge of local people as these projects progress. We will also continue to work with local flood action groups to develop emergency flood plans and share knowledge.

The next time we will be able to share information with communities is in summer 2019 when we will have our new modelling information. We need to make sure that the model represents what happens on the ground so that we can use it to make decisions about the best ways to manage flooding.

If you would like to be kept updated or share your experiences of flooding please fill out the forms in the sections below. If you are already on our list you do not need to fill out a form.

Our next webpage update will be later this summer. We will be developing separate pages for the other 3 areas as these projects develop,

Thank you for visiting our project information page. For any comments or feedback on our information page, please email





  • Recreational and commercial river users
  • Members of the public with an interest in the river, the species and conservation
  • Businesses
  • Charities
  • Statutory organisations
  • Members of the public
  • Elected representatives, including MPs
  • Local councils
  • Environment Agency customers
  • Local authorities
  • District and parish councils
  • Environmental bodies
  • Land owners
  • RFCCs
  • Water companies
  • Members of the public
  • Community groups
  • Flood action groups
  • Members of the public
  • Community groups
  • Members of the public


  • Flood management
  • Water resources
  • Habitats and wildlife