Revised 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

1.Introduction

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 benefits to all waterways users as well as to enhance good environmental practice. IWA considers that all navigation authorities should have policies in place 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 principal aims of IWA with regard to vegetation management on the waterways are: 

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

 2.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 out-sourced. 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. 

 3.Vegetation Management Standards 

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: 

3.1 Towpaths 

• Minimum width 1 metre, close mown, cut to 5 cm (2”) twice per year.  
• 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. 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 tree species growing in the hedge should be protected and allowed to reach maturity where appropriate. 
• Arisings from hedges and trees to be chipped on site or where necessary removed or burned. Burning must be as far away from hedges as possible and not under trees. Care should be taken not to smother existing vegetation when depositing shredded debris. Consideration should be given, where there are open areas near the site, to establish habitat piles or composting heaps for the benefit of small mammals, birds and insects. 
• 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. 
• 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. 

3.2 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. 

3.3 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 
• 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. 

4.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. 

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. 

5.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. 
• Trees at significant risk of falling across the towpath or navigation channel should be removed. 
• Trees should not be allowed to cause obstructions to sightlines required for safe navigation. 
• Minimum clearance over the towpath should be 2.5 metres. 

Trees along most broad river navigations have a positive rather than negative impact on the navigation and are often the responsibility of the landowner. Therefore IWA recommends that action be taken only when a problem is identified. 

6.Invasive Non-Native Species 

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.

7.References

This policy should be read in conjunction with the following IWA policies:   

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