Weed Cutting Dates & Guidance

weed cutting river itchen and river test

Weed Cutting on the Test & Itchen

Weed cutting, both instream and bankside, is a long-standing element of chalk stream management but can be controversial.

Vegetation is cut for several purposes, including access for anglers and for casting, maintaining a good diversity of instream habitat, preventing marginal silt buildup, controlling river water levels, and as a preemptive flood management practice.

The aim is to cut just enough weed to encourage fresh growth of modest size to ensure the weed will not go through a more natural but devastating cycle of dieback through over shading from excess clogged masses of weed.

Weed Cut Dates for 2025/26

Winter Open Period

Please keep those downstream of you informed about your plans for weed cutting. Owners are asked to ensure that cutting is completed before trout spawning begins in January until the end of March and that cut bank side vegetation is not allowed to fall in the river.

Riparian owners are asked to carry out bank maintenance and other works likely to cause displacement of silt before Christmas, to avoid damage to spawning. The advice of the Environment Agency should be sought before the commencement of any work, and the necessary land drainage consents obtained.

River Test

Weed may be cut from 14 October 2025 until 26 April 2026.

River Itchen

Weed may be cut from 2nd October 2025 until 15th April 2026.

Weed Cut Dates for 2026

The Environment Agency has now confirmed weed cutting dates for 2026. Please note any text in red in on the first page denotes a change to previous years.

River Test Weed Cutting Dates 2026 River Itchen Weed Cutting Dates 2026

Parish Councils are encouraged to make the dates available on notice boards, so that parishioners understand when they should and should not be cutting weed in the river. We are encouraging everyone to restrict weed cutting to what is absolutely necessary and to be very selective in what they cut. There is growing evidence that our aquifer recharge could be low this winter, which will increase the chances of drought next summer. Weed helps hold water in the river, so please consider that when cutting weed. Please note any text in red in on the first page denotes a change to previous years.

Dick Hawkes

Why Cutting Must Be Done Carefully

The timing, amount, and pattern of weed cutting are vital factors affecting weed growth and the management of potential adverse effects on the riverine environment.

If too much weed, or too much of one species, is removed – especially all at once – the river can lose critical habitat. It can also disrupt the natural interdependencies among different plant species, such as those between water crowfoot and watercress. Fish, insects, and the quality and level of the water can suffer. Cutting at the wrong time can also expose the riverbed or harm spawning areas.

Weed cutting should always be restricted to what is deemed necessary, be selective, and, where possible, carried out by hand. Mechanical cutting can remove significant amounts of weed and damage riverine habitat. The use of devices such as weed-cutting boats should be avoided unless absolutely essential.

Excessive cutting prior to the winter period can significantly reduce the availability of winter cover for fish, leading to increased rates of predation, particularly by piscivorous birds.

Good cutting keeps the river open and functioning while protecting the wildlife it depends on.

Test & Itchen Association Weed Cut Guidance

Consider the long-term health of the river
Weed cutting should be carried out in such a way that it supports ecological diversity (insects, fish, plants), not just to keep the channel tidy
Weed is not just a nuisance
It is a vital part of your river’s health
Cut wisely, not heavily
Light, well-placed cuts are better than wholesale removal
Timing matters
Avoid overcutting late in the season; preserve cover for winter
Work with your neighbours
Coordinate cutting, so you don’t cause downstream damage
Respect the rules
Comply with permissions, don’t dump trimmings into the water, and minimise silt and disturbance

Guidance for Riparian Owners

The Environment Agency has granted consent for general weed-cutting on the River Test. In the event of low river flows (and high water temperatures), the Environment Agency may request that weed cuts be postponed or reduced in extent in order to maintain water levels and quality. Cutting of weed outside of the authorised dates, without the Agency’s consent, constitutes an offence under Section 90 of the Water Resources Act 1991

Outside of the Winter Open Season, cutting should start at the beginning of the dates allowed. Please inform your downstream neighbour when you have finished clearing off and of any subsequent problems. Regular communication with your neighbours upstream and downstream is essential to ensure trouble-free weed cutting and clearing down. Weed-cutting boats should finish one day before the end of each cutting period.

Grass cuttings and bank trimmings must NEVER be put into the river. Depositing any form of solid waste in the river, including bankside vegetation, is strictly prohibited under Sections 85 and 90 of the Water Resources Act 1991

Weed cutting should be undertaken in a sensitive manner. Overzealous cutting of weed can harm river habitat and have a negative impact on fly life, fish and other wildlife.

Above all else, please be considerate and use your common sense. Do not send downstream what you would not want to receive from upstream.

Contacts in case of difficulties: River Test

The Association’s Volunteer River Test Wardens may be contacted on the following mobile numbers on the dates indicated in the weed cut documents [add link]. Please contact the T&I Office outside these dates if you have any weed cut issues.

Lt Col Nigel de Foubert 07796 622 208 During the weed cut

Mr Chris Geal 07710 063 456 During the clear down

Lt Col Keith Fisher 07711 931 812 The three days after clear down

Other Contacts:

Test & Itchen Association Paul Vignaux: 07340 865 502 or by email to: director@testanditchen.co.uk.

Solent Environment Agency Emergency HotLine

0800 80 70 60 (24hrs) (Mobile Phone Users must prefix 0800 number with a *)

Environment Manager, Environment Agency Tel. 03708 506 506

Romsey Depot

Canal Walk

Romsey

Hampshire SO51 7LP

Contacts in case of difficulties - River Itchen

River Itchen

Please report any weed cut problems in the first instance to the Test & Itchen Association: Paul Vignaux: 07340 865 502 or by email to: director@testanditchen.co.uk.

Anything you can do to investigate the cause of the problem will help the Association respond effectively.

Other Contacts:

Solent Environment Agency Emergency HotLine

0800 80 70 60 (24hrs) (Mobile Phone Users must prefix 0800 number with a *)

Environment Manager, Environment Agency Tel. 03708 506 506

Romsey Depot

Canal Walk

Romsey

Hampshire SO51 7LP

Why Weed in Chalk Streams Matters

Vegetation such as Ranunculus (water crowfoot) and Rorippa nasturtiumaquaticum (watercress) can:

Give vital shelter to juvenile trout, salmon and other fish
Help keep river gravels clean as the water speeds up around it
Maintain water velocity, raise water levels and keep the river cooler in summer
Support mayfly and other insect life
Help capture nutrients

The Importance of Aquatic Weed

On chalk streams like the Test and the Itchen, aquatic weed isn’t just something that is unsightly or “gets in the way”. A healthy amount and balance of in-river vegetation is vital for the ecology and well being of a river. Ideally every metre of river contained within a fishery should have a succession of weed beds which are healthy and vigorous and as far as possible contain all the most beneficial plants.

Preserving and enhancing the growth of clumps of Ranunculus (water crowfoot), Oenanthe fluviatilis (water-dropwort) and Callitriche (Water Starwort) and other submerged vegetation provides an essential refuge for invertebrates and fish, including juvenile salmonids, known as parr. On chalk streams, Ranunculus is primary habitat for salmon parr and for other small fish, and studies have shown that the more of it there is, the more parr it supports. Ranunculus thrives on good water flow and clean mud free gravel substrates and so this is also the sign of a river in good condition.

Whilst excessive buildup of any weed can cause silt accumulation, Ranunculus does help retain organic material, which can provide habitat for mayflies and other larvae whilst helping keep gravel runs between beds of submerged weed clean and healthy.

A river with bountiful aquatic weed increases water depth by up to 80 cm during summer months, helping keep the river cool during hot periods. Cutting needs to be adapted to the prevailing hydraulic situation and should be put on hold, if possible, or certainly applied with discretion, during times of drought or low flows. Each weed type is adapted to particular flows and so tends to thrive in different stretches of the river, for example Mare’s tail (hippuris vulgaris) favours deeper parts of the rivers and in areas of slower flows, and is often found in the middle and lower reaches of the rivers. No two years will be the same and the keeper needs a keen understanding of the river as the seasons and how the weed is adapting to light reaching it in cloudy or clear waters, the flow and temperatures.

Wild Trout Trust Guidance on Weed Cut Best Practice

Avoid cutting unnecessarily

Fixed cutting dates can sometimes motivate unnecessary cutting – do not cut weed unnecessarily. Care must be taken to avoid excessive cutting as this can significantly lower the water level, leading to decreased habitat availability and increased water temperature and risk from avian predation, particularly during low flow periods.

Understand the role of watercress

Watercress (Rorippa nasturtium-aquaticum) is often removed to control silt and reduce flood risk, but it is an important ecological plant. It provides valuable habitat for juvenile trout, captures nutrients, and supports a rich invertebrate community (around 21 associated taxa). Watercress and water crowfoot are seasonally linked—when one declines, the other increases—and this natural balance helps maintain water velocity in wide channels. Removing watercress in autumn or early winter (“edging-in”) disrupts this balance and removes important invertebrate habitat, so it is not recommended.

How to handle weed after cutting

The handling of weed after cutting is also crucial. Allowing cut weed to drift downstream lets invertebrates escape back into the river. Removing weed completely at the cutting site prevents invertebrates returning; briefly leaving it at the bank allows them to move back, but leaving it too long risks pollution through decay. Cut weed must never be left in the river because of deoxygenation risks and legal restrictions.

Avoid creating a monoculture

Completely removing “undesirable” species such as mare’s tail or common club rush should be done with caution, as these plants also support extensive invertebrate communities—sometimes more than Ranunculus. Care should be taken to ensure that significant stands of all species should be allowed to remain; a ‘monoculture’ of Ranunculus is an undesirable outcome to any weed-cutting programme.

Avoid heavy Autumn cutting

Extensive autumn cutting of Ranunculus and watercress on some rivers can help with flood defence and is cost-effective. However, it also has several drawbacks. Removing too much vegetation before winter reduces cover for wildlife, leads to lower Ranunculus growth the following year, may change the mix of plant species, harms invertebrates and can lower river levels in autumn and winter. Because of these impacts, heavy autumn cutting is not ideal from a conservation perspective.

Best Practice

Traditional hand-cutting in spring and summer, following the usual “side and bar” pattern, is likely the best balance for both fishery management and nature conservation.

In order to retain floral and faunal diversity, it is recommended that a maximum of 40% of weed (by area) should be cut at any one time.

Wild Trout Weed Cut Guidance

Membership

If you would like to support our work to conserve the Test, Itchen and Meon rivers and protect chalk stream salmon, then please help us by joining our association.

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