Frequently Asked Questions

Background



1. What are the Bow Back Rivers?
   
   The Bow Back Rivers are a 5½-km network of industrial tributaries of the River Lea which criss-cross the Olympic Park. They have been shaped by man over many hundreds of years for industry, transport and flood relief.


2. Why are they in such poor condition?
   
   The waterway infrastructure is actually in relatively good condition, largely dating back to a major works programme in the 1930s. Nonetheless the rivers have suffered from contamination from local industries, from pollution and fly-tipping from neighbouring businesses, as well as the decline in commercial boat movement. Furthermore, the 1968 British Waterways Transport Act effectively limited investment in their upkeep.


3. What are they used for now?
   
   With the exception of a few local people and enthusiasts the rivers are largely unknown and rarely visited. Despite the continuing problems of pollution, however, the waterways today host a range of wildlife habitats, have a relatively good network of towpaths and even a small community of narrowboats.




Restoration Plans



4. How have restoration plans developed?
   
   Restoration of the Bow Back Rivers has been a national priority for BW since 2002 and is one of the Mayor of London's policies in the London Plan. After London was chosen to host the 2012 games, the Defra agencies (Environment Agency, Natural England and British Waterways), and a range of other stakeholders (including London Thames Gateway Development Corporation, TfL and PLA), worked with the ODA on a plan to maximise the use of the waterways for wildlife, navigation, people and flood conveyance. The proposals extend beyond the Olympic Park - from Hackney to the Thames - and seek to create the most sustainable waterway restoration possible.


5. What is being proposed?
   
   The most sustainable waterway restoration possible. Improvements to the existing waterway infrastructure (walls, locks, channels etc), reinstatement of a water control structure (with lock) at Prescott Channel, resolution to the poor water quality in the area, naturalisation of the Old River Lea and enhancement of inter-tidal habitats on Abbey and Bow Creeks.


6. What is ‘Three Mills Lock'?
   
   The new lock and water control structure will reinstate an historic water control structure on Prescott Channel, Three Mills Island near Bromley-by-Bow, controlling water levels on the navigations to the north. It will incorporate a new navigable lock, fish pass and footbridge with a twin water control structure on Three Mills Wall River . This sluice will control water levels coming out of the navigable 'pound' and prevent the influx of the tide from under the tidal mill.


7. Why do we need a new lock?
   
   Currently around half the Bow Back Rivers are largely unnavigable, with too little water at low tide and too much at high tide. Without the lock commercial and leisure boating would be unsafe and impractical.


8. Where does the name come from?
   
   The lock has had various names throughout the construction project, and in June 2009 the lock was officially opened and named Three Mills Lock, reflecting its location on the historic Three Mills Island. The lock is also sometimes referred to as Prescott Lock. This name comes from a Major Prescott, who was a member of the Lee Conservancy Board which undertook the construction of the eponymous flood conveyance channel in the 1930s.


9. What does the new structure do?
   
   The structure retains the water on Prescott Channel and Waterworks River at a controlled, but naturally flowing, level, and 'lock-out' tidal waters, returning the system to its previously navigable state. By including a lock in the structure, we can open up navigation for larger vessels entering the Olympic Park.


10. What does it look like?
    
    The lock chamber will be 62m x 8m wide x 3m deep, enabling access for up to two 350t barges and a tug - with two pairs of hydraulic 'sector' gates. There is an adjacent water control structure comprising 'fish-belly' sluice gates, with a similar structure on Three Mills Wall River . The structure also has a 'fish pass' (enabling passage of fish upstream and downstream) and an access bridge for pedestrians and maintenance work.


11. What are the benefits of the scheme?


• 24-hour navigation north of Three Mills access for large (350t) barges
• saving up to 170,000 lorry journeys during the Olympic construction period alone removes need for temporary works for river wall improvements
• prevents influx of debris and detritus to Olympic Park on incoming tides
• increases fluvial flood storage
• improves access and leisure opportunities on and around water
• enables future restoration of House Mill on Three Mills Island


12. When will there be public access to the lock?
    
    The lock was opened to freight traffic in June 2009. The lock site will be open to the public from late summer 2009.


13. What other related works are planned on the rivers?
    
    Some spot dredging and bridge fendering is being undertaken and should be complete by the end of summer 2009. We also plan to complete the restoration of City Mill Lock and aim to restore Carpenter's Road Lock.




Water Transport



14. How will this help with water transport?
    
    By enabling access for large (350t) barges we will be helping to make water transport an economically viable and competitive alternative to road haulage for the Olympics and Legacy.


15. Why is water transport important?
    
    Water transport is intrinsically cleaner and greener than road haulage and the purpose for which many of London 's waterways were originally used. Each 350t barge will be able to save up to 34 lorry journeys and so reduce CO2 emissions and other environmental impacts.


16. What would the navigable dimensions of the rivers be?
    
    Above Three Mills Lock the water level would be 2.4m deep and have a 3m headroom under the lowest bridges (Stratford High Street and the Northern Outfall Sewer). Below Three Mills Lock the tidal creeks would have a four to six-hour tidal 'window' (depending on the state of the tide).


17. What sort of materials will be carried?
    
    During the construction phase, non-time sensitive bulk materials such as aggregates, sand, steel and waste. During the Games and the Legacy, construction materials, waste and recyclates.


18. Will the waterways be used for carrying visitors to the Games?
    
    We are discussing the potential use of the waterways for passenger transport both during the Games and in the Legacy period. This could include water buses, trip boats, restaurant boats and water taxis.




Wildlife



19. What impact will it have on wildlife habitats?
    
    The structure will have no affect on the richest habitats in the Lower Lea Valley - the reedbeds and intertidal mudflats which exist on Bow Creek and Abbey Creek. It will change the very poor inter-tidal regime north of Three Mills into a fluvial (freshwater river) system, creating opportunities for habitat enhancements all the way up to Hackney Marsh.


20. What species will be affected?
    
    Despite the poor quality of the habitats, pollution and hard river walls, the area provides a habitat for a variety of flora and fauna. These are often choked by a range of invasive species including Japanese Knotweed, Giant Hogweed, Himalayan Balsam and Chinese Mitten Crabs - which need to be destroyed under licence.
    Over time the environment will alter as the waterway will be changing from semi-tidal to fluvial habitat. But working with the Environment Agency, Natural England and other partners we plan to improve wildlife habitats in the area by improving water quality, removing invasive species, planting native species, putting in soft bank protection. The aim is to improve habitats for existing wildlife, such as kingfishers and sand martins, while encouraging colonisation by more species, such as water voles, otters, salmon and bats.




House Mill – the tidal mill on Three Mills Island



21. How will this impact on future plans to restore the mill?
    
    The new lock is an essential enabling work to any future restoration of the wheels under the tidal mill. We are part of the Three Mills Partnership that consists of representatives from: The River Lea Tidal Mill Trust, The Waterways Trust, English Heritage, London Heritage Trust, British Waterways, London Development Agency, London Thames Gateway Development Corporation, London Borough of Newham, Lea Valley Regional Park Authority and Leaside Regeneration. The partnership has submitted an application to English Heritage and other bodies to raise funds for an options appraisal which would help determine a sustainable solution for the House Mill and site. The options appraisal will tell the Partnership what is practically and technically feasible, the Partnership will then launch a fundraising campaign to restore the mill’s wheels and interior. Eventually it is hope that the Grade-1 listed structure will be restored for both education and interpretation and for hydro-electricity production.


22. How much energy could the mill generate?
    
    We estimate 160,000 kW hours - or the equivalent power usage of a small village of 40 homes. This would create a highly appropriate and sustainable revenue for the trust to maintain this important building.




Project Backing



23. Who supports the project?
    
    The project has been supported by a wide variety of stakeholders, statutory agencies and Government departments including: Defra, Department for Transport, Department for Culture, Media & Sport, Transport for London, Olympic Delivery Authority, London Thames Gateway Development Corporation, London Borough of Newham, the Environment Agency, Natural England, Greater London Authority, Port of London Authority, Lee Valley Regional Park Authority, Leaside Regeneration, Sea & Water, The Inland Waterways Advisory Council, the Parliamentary Waterways Group, The Inland Waterways Association, National Association of Boat Owners, Association of Waterways Cruising Clubs and the River Lee Tidal Mill Trust


24. How has the the project been funded?
    
    A funding partnership between the ODA, LTGDC, TfL, DfT and BW met the project cost of £23m.


25. How does this link with proposals for a 'Water City'?
    
    This is an important component of the ' Water City ' - a scheme backed by British Waterways, Leaside Regeneration and the Bromley-by-Bow Centre and making up part of London Thames Gateway Development Corporation's Lower Lea Valley Regeneration Strategy. The 'Water City ' seeks a mix of sustainable development and parkland in the area, set around a network of revived waterways rich with wildlife, footpaths, cycleways and boating activity.