Best Practice

1. Channel Risk Categorisation for Maintenance Planning

An IDBs’ routine maintenance work should be designed and adapted to suit the individual channel and local area flood risk. Each channel and area is different and should be managed differently.

Rotational management is known to deliver a good balance of providing good quality habitat for biodiversity, managing maintenance costs and managing flood risk and water levels. This usually involves cutting bank-sides alternatively every 2 or 3 years, and regular and light desilting such as a 3 or 4 year rotation. This delivers positive outcomes for biodiversity and is cost-effective for IDBs.

Some channels have to be managed more intensively to reduce the risk of flooding. For example, if a channel is flashy and has a history of being quickly bank-full following weather events, at all times of the year, keeping a clear channel is critical to prevent water backing up and flooding areas upstream. This would be deemed a high category channel and a more intensive vegetation and silt management regime should be followed in this case.

Some channels are larger, such as pump drains, or are only serving to relieve seasonal waterlogging in the immediate area so vegetation can be less intensively managed to provide more habitat for wildlife. Even in the highest risk channels, there should always be room to maintain some bank and marginal vegetation, even if it is only 30cm on one side, and there are practical benefits of doing so. Marginal vegetation binds the toe of the bank and bank vegetation binds the bank face, reducing the risk of bank and soil erosion and costly bank slips.

We have developed a range of guidance to assist IDBs in categorising their channels and to define their routine maintenance operations:

• Step by step guide to categorise channel risk and define work approaches:

• Template to help IDBs define and record the risk of each channel and plan the work approach:

• Standard Operating Procedures for flail mowing, aquatic plant management and desilting: email enquiries@middlelevel.gov.uk for up to date copies.

2. Standard Operating Procedures for Routine Maintenance Operations

A suite of environmental Standard Operating Procedures (SOPs) are available, covering regular routine maintenance such as flail mowing, de-silting, biosecurity and managing aquatic vegetation. Each SOP is designed to deliver compliance in relation to a whole range of protected species and to deliver general biodiversity enhancements. For the most up to date copies of all SOPs please email enquiries@middlelevel.gov.uk.

3. Ecological Assessment of Non-routine Works

For non-routine work, to minimise environmental risks, an ecological assessment is required prior to any works commencing to check if there is a risk of impacting any protected species and habitats in or around the area of works (see the protected species page for more information on protected species commonly found in and around IDB channels).

To request this assessment, the ESR should be completed and returned to us, setting out the details of the proposed work (first couple of pages only, we do the rest!). As much notice as possible (a year is not too much notice) is necessary for such work requests as a number of protected species can only be surveyed at certain times of the year, and mitigation can only take place at certain times too. For example, you can’t survey for bats in the winter as they are hibernating or displace water voles between April and September as they are breeding.

For more information about water vole displacements see our guide.

On receipt of an ESR, MLC ecologists plan and undertake any necessary site surveys in the most appropriate season, and identify any licenced protected species mitigation that will be necessary ahead of the proposed works commencing. The form is then completed and returned to the IDB with the survey results, recommendations and requirements, so the works planning can commence. If protected species mitigation are required, they will need to be planned and carried out by a licenced ecologist ahead of any works commencing.

Non-routine work can include replacement or installation of a culvert, sheet piling or wooden toe boards and piling, bank repair or reprofiling and removal/management of scrub and/or trees. We define the work approaches necessary in the ESR to ensure that work is completed compliantly and the opportunity is taken to enhance habitats for wildlife, as is required by law.

For some more intrusive works, or works near or in protected sites, more detailed assessments may be required by law. For example, if a channel or their banks are to be deepened, widened, straightened or otherwise improved or altered or weirs or other watercourse obstructions removed or altered, an Ecological Impact Assessment (EIA) is likely to be needed. If works are taking place in or near a designated site, a Habitats Regulations Assessment (HRA) may also be required. However this will be picked up in the ESR process.

See here for more information about EIAs:

and HRA’s:

Enhancements could include using green-engineered solutions such as pre-planted coir roll to provide bank toe stabilisation instead of wood or concrete or an enhanced bank seed mix with grasses and some wild flowers to improve bank diversity and reduce soil erosion after a bank repair.

To request ecological assessment for IDB non-routine works– please complete and return the ESR to us at the earliest opportunity.

4. Biodiversity Action Plans

Biodiversity Action Plans, now a statutory requirement, are an audit of the most valuable habitats and species that are found within each IDB district and details what action the IDB will take to conserve and enhance them. IDBs should regularly review and update their BAP with the support of MLC. The latest versions are available via each IDBs individual landing page but all BAPs are currently being updated (July 2025) so check back soon to see any newly approved BAPs.

5. Invasive & Non-Native Species (INNS)

Invasive non-native species (INNS) are one of the leading causes of biodiversity loss worldwide and are thought to cost the UK economy £1.9bn annually (CABI, 2023). INNS can establish quickly and can be devastating to our local wildlife. Some invasive plant species can block our channels and damage our water level management structures, potentially increasing flood risk.

Some invasive species that are unfortunately already established in our waterways include Chinese mitten crabs, American signal fish, Crassula, Zebra Mussels and Azolla (water fern). We manage and control these species as best we can.

IDBs are required to have stringent biosecurity procedures to prevent the spread INNS through their work. Links to the IDB Biosecurity Policy and procedures can be found below, and the Board Approved versions are available from each IDBs individual website.

For more information on what INNS to look out for and identification, please visit:

Check Clean Dry

It is also vital to promote the “Check-Clean-Dry” procedures to users of all MLC waterways. The “Check-Clean-Dry” procedures can be accessed here:

Report INNS

If you think you have spotted an invasive non-native species of plant or animal in or around our waterways please let us know ASAP so we have a good chance of controlling the spread as soon as possible.

INNS can establish quickly and can be devastating to wildlife as well as potentially increasing flood risk.

Please send us a photo, location and any information to enquiries@middlelevel.gov.uk so we can check and take prompt action.

Floating Pennywort

One species we currently do not have in our waterways is FLOATING PENNYWORT and we are keen to keep it that way.

Help us to spot Floating Pennywort using the resources below and report any suspected sightings of the plant to us as soon as you can.

The plant is very costly and problematic to eradicate and early control is key to control.