This version:

• Edited February 2023 to February 2024
• Approved by Navigation Committee 31st January 2024
• Approved by Trustees on 21st February 2024

Original policy published January 2015

Previous version updated October 2020

This document sets out the policy of The Inland Waterways Association (IWA) regarding the management of vegetation by navigation authorities on inland waterways

Policy

Vegetation, when properly managed, is an important and attractive feature of the waterway environment. It also fulfils a key role in the stabilisation of banks, consolidating embankments and water table control. The uncontrolled establishment and growth of vegetation alongside a navigation can, however, cause personal injury, damage to craft, reduce amenity, and adversely affect the water environment.

IWA considers improved management of vegetation is essential in order to optimise the value of inland waterways in helping to address environmental concerns, while ensuring the safety of all waterway users and maximising benefits to them. IWA considers that all navigation authorities should have policies in place that give proper priority and attention to the management of vegetation along the waterways for which they are responsible, and will encourage navigation authorities to comply with such policies.

The principles set out in this policy apply to navigation authorities, to their contractors, and to volunteer groups. IWA also expects riparian owners to maintain trees and deal appropriately with invasive non-native species.

The principal aims of IWA with regard to vegetation management on the waterways are:

• Protection of waterways infrastructure and users from adverse effects of plant growth.
• Protection and enhancement of the natural environment and heritage assets.
• Maintenance of a navigable channel suitable for propeller-driven craft and unpowered craft.
• Access to the waterway edge by boat and from bank at appropriate locations for long-term and casual mooring.
• Towpaths that are maintained to ensure all users can use them easily and safely.
• Removal of hazards to boaters where marginal vegetation growth causes obstructions to sightlines required for safe navigation or physically obstructs the navigation.

Guidance

1. Establishment of Standards

IWA is cognisant of the constraints placed on navigation authorities by environmental controls and legislation regarding the time of year as well as the techniques to be employed to minimise disturbance to wildlife caused by control of vegetation. However, vegetation management on a navigation should not result in any deterioration due to compliance and, where possible, should contribute to achievement of environmental targets. IWA would like to see a uniform approach adopted nationally by all navigation authorities for the management of vegetation, especially when the control has been outsourced. IWA will encourage and support navigation authorities to manage vegetation properly so that these standards can be met and exceeded. This includes the support and encouragement of navigation authorities to work with volunteers to manage vegetation where safe and practicable. Volunteers are already involved to a great extent in the removal of invasive non-native species such as Himalayan Balsam (www.waterways.org.uk/invasivespecies), the cutting back of vegetation encroaching onto towpaths, the removal of saplings growing out of the bank between the canal and the towpath, and occasionally, and with the right equipment and training, the tackling of offside vegetation. Although volunteers are already involved in this work across the waterways, there is potential to involve them further and IWA would support navigation authorities in achieving this.

2. Vegetation Management

It is considered that periodic audits (at least annually) should be carried out of vegetation along navigations to identify where work is required to implement a plan to achieve and maintain the satisfactory standards which are shown below:

2.1 Towpaths

• Minimum width 1 metre. For grassed paths this width should be close mown, cut to 5 cm (2”) twice per year.
• All saplings, trees and shrubs growing between the towpath and the water’s edge should be removed at least once a year to avoid them becoming safety hazards, damaging banks and becoming progressively more difficult to remove.
• In rural areas with grassed paths a soft vegetative strip should be left to the canal edge. To encourage the growth of more diverse and less vigorous wild plants, the vegetative strip should be treated like a meadow, being cut to about 5 cm (2”) twice a year. Where possible an ecotone (strip of herbaceous flowers/grasses) should remain uncut to a minimum of 30 cm from the edge of the hedgerow. The walking surface should be higher than the vegetative strip to prevent ponding.
• Overhead clearance of 2.5 metres from hedges or specimen trees for the full width of the towpath.
• Historic boundary hedges should not be removed.
• Hedges between the towpath and adjacent land should, ideally, be laid and new plantings inserted into depleted sections. Saplings of suitable native tree species growing in the hedge should be protected and allowed to reach maturity where appropriate.
• Where the towpath is a public right of way throughout its length it must be available for safe public use, including disabled access and including while works are being carried out.
• Where hedges are not being allowed to grow for the purposes of hedge-laying, and excluding specimen or single trees, towpath boundary hedges should be regularly cut so that views are not obscured.
• New hedgerows should be planted with 7 different wooded species to enhance ecological value and hedgerow diversity and in rows of two, with 6 – 9 saplings per square metre.

2.2 Short-term Moorings

• Where reed fringes are maintained, there should at intervals be access to the bank for boats, with gaps long enough for boats of the maximum dimensions for the waterway. These should also allow safe access for canoes and other unpowered craft in case of need.

 2.3 Permanent Moorings

• Management of vegetation at permanent or long-term mooring sites should ensure that safe access to boats is maintained and that vegetation does not interfere with mooring a boat or the safe use of any designated mooring site.

 2.4 Lock and Bridge Landings/Offside Lock and Bridge Landings

Management of vegetation at boat landings providing access to locks, bridges and other facilities or used for launching and recovery of canoes should ensure as a minimum:

• Safe use of boat landings, locks, bridges and canoe access points
• Protect structures from damage
• Maintain good biodiversity.

This should be achieved by:

• Short mowing a 2 metre wide path along the edge of the landing
• Short mowing a 2 metre wide path to each landing or canoe access
• Short mowing of lock surrounds alongside each lock to a distance of 2 metres beyond the beams of the open lock gates
• Trimming back any trees or other plant growth so as not to overhang the canal
• Maintenance of adequately deep water, cleared of emergent or submerged plant growth along the length of the landing
• Encouragement of suitable native marginal emergent plant species, as well as taller herbaceous species on the bank on each side of the landings and canoe access points, to direct boat users to the proper facility
• Regular clearance of herbaceous and woody plant growth from lock and bridge walls, lock gates and adjacent locations where roots could cause structural damage.

 2.5 Disposal of Arisings

Arisings from hedges and trees should be disposed using the following hierarchy:

• Stacking on site within the hedge borders to create log piles or dead hedges to provide a useful resource for fungi, invertebrates, small mammals and reptiles.
• Composting off site. Removal of the arisings to a suitable council depot for composting or a storage location on the waterway or restoration site.
• Chipping on site. The use of chippers requires the operator to be trained and certified. Use of chippers is covered under the Waterway recovery Group Driver Authorisation scheme as category 17. Outside organisations conduct training courses in the safe use of chippers. The chipper may be bulky to manoeuvre on a towpath and may need to be located away from where the arisings are being generated. Care must be exercised when refuelling the chipper. Funnels must be used and spill kits available for any spillage. One proviso is that chipping on sites where dormice could be present, needs to be done with care during their hibernation period (roughly October to March incl.) and advice from a suitably qualified ecologist may be necessary.
• Use as firewood. The arisings would be removed from site and prepared for use as firewood.
• Burning on site. This is the last resort. Bonfire require a D7 exemption certificate from the Environment Agency. This is a form that can be completed online. Bonfires should be sited so as not to cause a nuisance and must be controlled at all times. They should not be sited on a public highway, or close to animals or their habitat, fences, power lines, roads, railways, slopes or flammable material. The source material should be kept away from the fire. Any bonfire should be dowsed at least one hour before the end of the working day and checked to make sure it is extinguished before leaving the site.
• While not currently mandatory, a call to the local fire service to inform them of a ‘controlled burn’ ahead of lighting a bonfire is much appreciated, as it anticipates a well-meaning member of the public reporting a fire which the fire service is then obliged to attend urgently.

3. In-channel vegetation

It is appreciated that aquatic vegetation provides valuable structural habitat for fish, invertebrate animals and other plants but excessive growth of emergent species can restrict the width of the navigation channel. Submerged and floating species can foul boat propellers if present in the main navigation channel. Excessive growth of filamentous algae such as blanket weed (Cladophora spp.) or invasive species such as floating pennywort (Hydrocotyle ranunculoides) can cause problems for navigation as well as oxygen depletion in the water. Poor water quality encourages the growth of weeds.

Uncontrolled in-channel vegetation can adversely affect navigation, diversity, and flood risk management and IWA will encourage and support navigation authorities in controlling and removing these plants. In particular floating reed beds need to be removed. There are regulations about weed control and disposal and the use of herbicides. Environment Agency guidance should be consulted (https://www.gov.uk/topic/environmental-management/wildlife-habitat-conservation). 

4. Trees

• There should be no trees between the towpath surface and water’s edge.
• There should be no trees within 2 metres of a structure such as a lock, building etc.
• Trees intruding on operating space such as landings etc should be removed within 1 year of noting.
• The general condition of trees should be regularly (e.g. annually) noted as part of routine vegetation maintenance. Trees at significant risk of falling across the towpath or navigation channel should be removed.
• Trees whose roots cause an uneven surface along the towpath or access to towpath, or damage to constructed stepped and ramped access, should be removed as necessary.
• Trees should not be allowed to cause obstructions to sightlines required for safe navigation.
• Where there are trees on each side of the waterway they should be kept trimmed so that a ‘canopy’ over the water does not develop.
• Minimum clearance over the towpath should be 2.5 metres.

 Trees along most broad river navigations are often the responsibility of the landowner. Therefore IWA recommends that action be taken only when a problem is identified. 

5. Invasive Non-Native Species

Regular movement of boats can be helpful in keeping down native weed species, but there is a downside where invasive species are involved. A piece of (for instance) Floating Pennywort cut by a boat can regenerate in a few days, forming a thick mat at a new location.

Where found invasive non-native species should, if practicable, be removed. If the growth is extensive then action should be taken to reduce its presence by restricting further growth pending action for eventual removal of the plant. IWA will encourage and support navigation authorities in controlling and removing these plants. For further details refer to the GB non-native species secretariat website at https://www.nonnativespecies.org/

6. References:

This policy should be read in conjunction with the following IWA policies at https://waterways.org.uk/about-us/library:

• Standards for Construction, Restoration and Maintenance of Inland Waterways
• Towpaths Policy