Facts and Issues Associated With The Bristol Avon (by Alan Aldous)

This summary is a compilation of facts and issues as understood based on many years of involvement with the Bristol Avon. It does not claim to be definitive as legislation and responsibilities change and reference documents are updated.

River Avon Users

This group was formed in 1979, originally under the auspices of the South West Sports Council, to minimise potential conflict between different ‘users’ of the river. Representatives include sailing, rowing, canoeing, angling, cruising, commercial interests, environmental groups, Kennet & Avon Canal Trust, Saltford PC, plus Canal and River Trust (CRT - ex British Waterways) and/or other parties as and when necessary.

The Waterway

  • 12 miles of the River Avon from Hanham to Bath was made navigable in 1727, and eventually became part of the 89 miles of the Kennet & Avon Waterway to Reading, completed in 1810.
  • Until the completion of the restoration of the canal section of the Kennet & Avon, the river was an isolated section of waterway as far as Bath.
  • The Kennet & Avon Waterway now forms the only cross country route suitable for wide beam ‘barge’ style craft in the south of England.

Governing Authorities

  • Canal & River Trust (CRT) is the navigation authority from Hanham Lock to Thimble Mill in Bath (where the Widcombe lock flight of the canal joins the river).
  • There is no official navigation authority for the 1 kilometre upstream of Thimble Mill to Pulteney Weir in Bath, which is the limit of navigation for all craft. (In such circumstances, information presented at a recent Coroners enquiry was that under Common Law the role defaults to the County, ie now Local Authority).
  • Two ‘Trip Boats’ also operate on the isolated section above Pulteney Weir as far as Bathampton Weir.
  • The Port of Bristol (PBA) is the Navigation Authority below Hanham Lock.
  • The river is designated ‘Main River’ by Environment Agency (EA) for flood protection and land drainage purposes, and EA is responsible for environmental topics on the whole river.
  • All structures in the river bed need Flood Defence Consent from the EA (previously known as Land Drainage Consent). See EA's website.
  • Sewage Discharge Consents are issued by EA to Water Companies to discharge water and sewage from CSO’s at times of heavy rainfall.
  • Local Authorities are responsible for development and Planning Permission.

Ownership

  • Most of the river remains in private ownership, including mills and weirs.
  • CRT as Navigation Authority owns the locks and islands, and very little land.
  • Bath & North East Somerset Council owns some riverside land, the exact amount and location is not public knowledge.
  • South Gloucestershire Council owns no riverside land.
  • Riparian ownership includes the bank and half the bed of the river.

Riparian Water Rights (or simply Riparian Rights)

  • The origins of riparian rights are in English Common Law, and in England and Wales are premised on Natural-Flow Doctrine, where each riparian owner has the right to receive natural water-flow of undiminished quantity and unimpaired quality.
  • Each owner has ‘Rights’ but also ‘Responsibilities and Duties’ reflecting Common Law that are set out in an EA document entitled ‘Living on the Edge’. Available at EA's website.

Usage

  • The river has always been a leisure attraction due to its location between Bath and Bristol. Some locations such as the Shallows at Saltford were described as ‘honeypots’ by the South West Sports Council over 30 years ago. There are long established rowing clubs and a sailing club on the river, three off-line marinas, and the river is heavily used by canoes.
  • Since the full reopening of the Kennet & Avon waterway, the size and type of craft using river has changed dramatically from small GRP cruisers to substantial wide beam craft of steel construction.
  • There are several large hire boat fleets located on the canal section between Bath and Devizes whose craft use the river (CRT licence covers to Hanham Lock).
  • The river has good coarse fishing. Fishing Clubs purchased angling ‘rights’ on some lengths in the 1930’s, so there is potential conflict of interest if there is mooring on these lengths. In the 1970/80’s the river was used for national angling competitions, but is less well used now due to increased boat traffic.
  • Several Rowing Clubs are located on the ‘long mile’ above Kelston Lock, and this stretch is extensively used for rowing, with several regattas being held each year. A Heritage Lottery Fund grant was given in 2012 to improve rowing facilities.
  • The Bristol Avon Sailing Club is based at Saltford. Any mooring in the pound upstream of the Jolly Sailor, whether temporary or permanent, can seriously limit the ability of the Sailing Club to practise and enjoy their sport.

Flooding

  • The river is prone to flash flooding at any time throughout the year. River levels can rise several feet in a few hours and cause a significant hazard to navigation due to increased flow rate.
  • The serious flood of December 1960 led to the Bath Flood Defence Scheme, seven people lost their lives in the 10th July 1968 flood that destroyed several bridges in Keynsham. The last major flood event was October 2000. Sustained flooding throughout 2012 caused the river to be closed to navigation for extended periods.
  • The river through Bath from Pulteney Weir to Twerton Sluices lies within an engineered channel with piled sides and has limited width.
  • River level in Bath is controlled by Twerton sluice gates that are owned and operated by EA, these occasionally ‘maloperate’.  Failure of the gates can cause the river level in Bath to rise or fall, with consequential and opposite effects downstream in both water level and rate of flow.
  • Any potential increase in flood risk, from whatever cause, is a very sensitive issue for affected communities downstream of Bath.

Tidal Impact

  • Avonmouth has the second highest rise and fall of tide in the world, up to 14.65 metres measured from the Kingroad datum. Actual figures are affected by the lunar cycle and high/low atmospheric pressure.
  • The river is tidal to Netham Lock on all tides, but tides over 12.6m at Avonmouth overtop Netham weir, so the river becomes tidal up to Hanham Lock. This varies from approximately 100 to 140 days per year.
  • Very large spring tides also overtop Hanham Weir so the river is effectively tidal up to Keynsham Lock. No data is available on number of occasions this occurs.
  • During very high tides Bristol becomes ‘tide locked’, meaning that until the tide drops, no land drainage is possible from the whole river catchment area. This has a significant effect on the river, because the river becomes temporarily unable to discharge, stopping flow and raising water levels for a period. This phenomenon is known as ‘the backwater effect’, and if coincident with the river in flood can be noticed as far upstream as Mead Lane in Saltford.
  • The ‘backwater effect’ noticeably alters both flow rates and river levels as the tide changes because the river is either stopped from discharging, or allowed to discharge the excess volume that has built up.

Lock Facilities

  • The current fixed height landing stages at locks were constructed in 1993/4 before the Kennet & Avon Waterway was fully re-opened, and, at the time would accommodate three or four small craft typical of those using the river. The landing stages will now accommodate only one 72 foot craft, and, if this is a wide beam, there is restricted ability for other craft to exit the locks.
  • During major flood events, all locks with the exception of Twerton are totally immersed, including the fixed height landing stages. It is very ‘unwise’ to navigate the river in such conditions.
  • There is no landing stage below Swineford lock, only a concrete causeway with mooring bollards. Even in mild floods this causeway becomes submerged so there is no safe landing facility, a situation exacerbated by tidal conditions.
  • Because the Bristol Avon has a very high fluvial content, silting is a major issue on the river, especially behind lock gates.
  • CRT has obtained Planning Permission to install safety booms at all weirs.

Moorings

  • Because the river is predominantly in private ownership, provision of new facilities has always been a problem.
  • There is a serious shortage of short-term moorings making it particularly difficult for visiting craft to stop overnight.
  • All waterways now experience an increased number of people who wish to live aboard boats. The problem is beginning to manifest itself on the river.
  • There is unfulfilled demand for residential moorings.
  • Moorings below Pulteney Weir and at Churchill Bridge in Bath are affected by changes in river level.
  • Bath & North East Somerset Council is the riparian owner of the moorings below Pulteney Weir.
  • British Waterways installed floating pontoon moorings at Hanham Lock, Keynsham Lock, and at the old railway bridge about 1 mile upstream of Keynsham. These provide the only ‘safe refuge locations’ on the river available for visiting craft in the event of being caught out by a sudden flood event.

Navigation Headroom

  • There is limited headroom at both Churchill Bridge in Bath and at Keynsham, both becoming impassable with high river levels.
  • Churchill Bridge is just downstream of where the canal joins the river at Thimble Mill.

Water and Sewage Disposal

  • There is one fresh water and sewage disposal facility on the river provided by Wessex Water between Swineford and Saltford locks. This is on a rise and fall mooring pontoon.

Floating Detritus

  • The practice of weekly removal of floating detritus carried out by the Bristol Avon River Authority ceased when the National Rivers Authority was created in the 1980’s.
  • Currently all floating detritus detained at Twerton sluices continues to be discharged downstream by EA, and is an ongoing issue for all ‘downstream’ communities and riparian owners, including CRT.

Removal of Fallen Trees

The ‘understanding’ of the party responsible for removal is :-

  • If the tree is still attached at the root – the riparian owner.
  • If it is a flood defence hazard – the Environment Agency.
  • If it is a navigational hazard – the Navigation Authority.

Alan J Aldous  BSc CEng MIET
Original - 26.04.12
Latest Review - 06.12.13

The Current Situation on the Bristol Avon