An impoundment is a dam, weir or other structure within inland waters that can permanently or temporarily change the water level or flow. This includes:

• dams
• weirs
• fish passes
• hydropower turbines
• sluices
• penstocks
• culverts
• lock gates
• retaining walls
• flumes
• reservoir embankments
• temporary diversions during construction work

You must have an impounding licence before you start towork construct,on alterbuilding ora removenew an impoundment structure, even in an emergency.

If you have an existing licencestructure youdoes maynot needcurrently tohave changean itimpounding iflicence, you wantmust toget alterone orbefore removeyou thestart structure.

Anwork impounding licence will set out:

• the manner and extent of the impoundment structure and any conditions related to itsalter constructionor andremove operation
• any diversion works required which are associated with the construction

There are some situations where you may not need an impounding licence.

Exemptions

You do not need an impounding licence if your activity is exempt.

The exemptions are for:

• works constructed without a licence before 1 April 2006, except when the Environment Agency gives notice that a licence is needed
• navigation,public harbourauthorities orthat conservancymanage authoritiesor thatown obstructwaterways or impedeharbours theconstructing flowany ofnew waterimpoundment, inaltering waterwaysan orexisting harboursimpoundment, theyor manageobstructing inor impeding the courseflow of inland waters while using their powers or carrying out their duties
• impoundingimpoundment works authorised by a drought order or drought permit
• structures and works authorised by legislation (for example an act of Parliament)
• construction – a licence may be required if you plan to alter or removealteration the structure
• works authorised by a development consent order, if the Environment Agency has agreed that an impounding licence is not needed
• when the Environment Agency gives notice requiring impoundment only for the purpose of screening or passage for eels

Low risk impounding activities

Some impounding activities have a low impact on the environment and other water users.

The Environment Agency will not normally need you to apply for an impounding licence for:

• worksfish constructedeasements afteror 1passes Aprilthat 2018have formal written approval by orthe onEnvironment behalfAgency ofand ando internalnot drainagesignificantly boardaffect inthe distribution of flow over the districtweir
• placing theya managenotch in thea courseweir to encourage fish migration
• placing woody debris across part of theirthe dutieschannel to diversify flows
• worksflap constructedvalves afterthat 1only Apriloperate 2018during withinflooding
• fixed acontrol managedor wetlandpassive systemflood ifprevention structures within the channel that only hold back flood water (structures with movable gates or sluices require an impounding workslicence)
• small aremeasurement forstructures, thesuch soleas purposev-notch ofor small rectangular weirs The Environment Agency will not normally require a licence application for:
• refurbishing a sluice
• re-pointing (block work structures)
• repairs (for example to expansion joint, stone pitching or bank or wall)
• void filling (‘solid’ structures)
• managing vegetation
• de-silting
• re-positioning (rock, rubble or block work bank protection structures)
• replacing elements that do not contribute to phased replacement of the wetlandwhole systemstructure
• re-facing
• skimming –or managedcovering
• blockage wetlandremoval, systemincluding isscreen definedclearing
• embankment ingrouting

Other regulationactivities 2that Waterwill Abstractionnot normally require a licence are:

• works that temporarily divert water during construction or maintenance of a structure and Impoundingdo (Exemptions)not Regulationsaffect 2017 any other water users, rights or the environment
• impounding works carriedor outchanges into the impoundment to reduce or avoid an emergencyimmediate bythreat to human life, property or the environment during an emergency
• any activity outside the channel, for example on behalftop of navigation,the harbourriver banks, such as installing or conservancymaintaining authoritiesbridge –supports aor notificationflood mustdefences
• work bein sentthe river, parallel and adjacent to the Environmentbank Agencythat withindoes 5not dayssignificantly ofnarrow the workchannel, commencing;for emergencyexample installing sheet piling, rip rap and rock revetments for erosion protection
• installing a wave wall on an existing reservoir dam that is definednot inintended regulationto 10impound Waterany Abstractionextra andwater
• increasing Impoundingthe (Exemptions)height Regulationsof 2017 spillway sidewalls (that does not alter the impounding level)
• altering, moving or constructing a spillway without increasing the impounded level or changing the downstream flow regime to the detriment of the environment

Low risk impoundingimpoundment activities

checklist

SomeIf impoundingyou activitiesanswer that‘no’ requireto all of the questions on this checklist, then you are not likely to need an impounding licencelicence. haveKeep a lowcopy impactof onthis thechecklist environmentfor andyour otherown waterrecords. users.

The Environment Agency willmay notask normallyto takesee enforcementyour actionchecklist ifand supporting evidence which shows how you doassessed that you did not need a licence.

1. Do surveys reveal any existing abstractions, including unlicensed ones, which may be affected by the proposal?

2. Are there any other water users or riparian rights or interests that may be affected?

3. Will the changes cause parts of the weir to suffer significantly reduced flows?

4. Is the proposal within, or likely to have an impoundingimpact licenceon fora theseSite lowof riskSpecial activitiesScientific ifInterest, youSpecial meetArea theof conditionsConservation, Special Protected Area or Ramsar site?

5. Are planned changes in river flow likely to cause significant change to invertebrate habitats?

6. Does the Environmentproposal Agency’saffect regulatoryprotected positionspecies statement low(not riskfish) impoundingthat activities:may RPSlive 302.at the site or elsewhere in the catchment?

7. TheAre regulatoryplanned positionchanges doesin notthe applyriver flow likely to cause a significant change in the macrophyte and diatom communities?

8. Will the proposal impact on either the up or downstream passage of fish (including eels)?

9. Will the proposal impact on any otherfish legalspawning requirements.or nursery areas?

10. Will the proposal cause sediment movement or deposition to be substantially altered above or below the site?

11. Will pollutants be discharged or mobilised into the river during construction or operation?

12. Is the proposal likely to significantly increase river turbidity or significantly alter movement of sediment?

13. Does the scheme involve construction of a new raised reservoir with the capacity of 25,000 cubic metres or more?

14. Will the proposal cause erosion of the river banks up or down stream?

Apply for a licence to impound water

Find out how to apply for a licence to impound water.

Other permissions you may need

You may also need to apply to the Environment Agency for an environmental permit for a flood risk activity when you build in, over or next to main rivers. For rivers and watercourses that are not main rivers you must apply to your lead local flood authority for consent.

If you want to abstract (take) water, check if you need an licence to abstract water.

Get advice

If you are not sure if your proposal needs an impounding licence, you can get advice using the Environment Agency’s enhanced pre-application service.