RP33: Large leaky woody dams

How much willyou’ll be paidpaid 

£764.42 for each damdam.

WhereHow to use this item benefits the environment

ItLeaky iswoody availabledams forslow Countrysidethe Stewardshipmovement Higherof Tier,water Midafter Tierhigh rainfall and Capitalhelp Grantspush butwater only:onto floodplains. They can also increase the recharge of groundwater. This increases the temporary storage of flood waters within water channels and on floodplains, so:

• withhelps delay the supportpassage of flood water downstream
• allows sediment to settle out
• reduces downstream flood risk

This item can help you protect, recover and approvalimprove biodiversity on your land.

Where you can use this item 

You can only use this item with support from Catchment Sensitive Farming (CSF) either in:

• incatchments where permeable soils and geology allow for recharge (capture and storage) of groundwater
• catchments targeted for flood risk measures or water resource benefits

You can also either use this item for:

• for dams in streams and river channels between 3 metres (m) and 5m wide

How

ephemeral thisstreams itemand willsurface benefitwater therun-off environment

Leakypathways woodywhere dams slow the movementoverall length of waterdam andrequired helpis pushless flowsthan onto15m

Catchment theSensitive floodplainFarming duringprovides floods.advice Thiswhere increasesthere temporaryare storagewater ofquality or flood watersrisk withinissues waterlinked channelsto andfarming.

You outmay onneed toconsent from the floodplain,Environment helpingAgency, delay the passagelead oflocal flood waterauthority, downstream,or allowinginternal sedimentdrainage toboard settlebefore out,starting andany reducework. downstreamRead floodguidance risk.on owning a watercourse for more information. 

Requirements

YouCheck must:

• sendwith theNatural writtenEngland supportif andyou’ll approvalneed froma CSFfeasibility withstudy. yourSpeak application
• followto theCatchment indicativeSensitive drawingsFarming inabout thea Higherwater Tierholding Annexstructure 2caction forplan. 

  What maximumyou effectiveness

must do to use this item

You must:

• construct the dam from logs large enough to span the water channel and out on to the floodplain to provide a stable and long-lasting structure
• secure the dam in line with the requirements of the Environment Agency or Leadlead Locallocal Floodflood Authorityauthority consent or exemption (where required)
• align dams at right angles to channel banks or water flow to reduce bank scour
• in streams (permanent or winterbourne), build dams to allow lownormal flows to always pass unimpeded – set them at all0.3m timesabove normal flow levels
• site dams on slow flowing reaches of the water course that have on average 2m of floodplain on either side
• build dams to a height sufficient to encourage water to spread onto the floodplain upstream of the dam
• build dams in series (minimum 3 dams) at a spacing between dams of about 5 to 7 times the width of the channel
• make sure dams are not installed directly upstream of pinch points such as bridges or culverts that back up flows and are likely to swamp the dam
• check and maintain dams to keep the structure effective – ensure the free gap underneath has not become blocked by debris
• follow the requirements set out in any Feasibilityfeasibility Studystudy or Catchment Sensitive Farming (CSF)water Designholding Planstructure action plan (if applicable)

Keeping

Evidence records

Before you apply,must youkeep 

You must seekkeep advicewritten support from theyour EnvironmentCatchment AgencySensitive andFarming whereadviser relevantand theprovide Leadwith Localyour Flood Authority to check if you need consent to carry out the planned work.application. 

You must also keep the following records and supplyprovide them with your payment claim:claim: 

• photographs of the completed works in place and installed
• any consents and permissions from the Environment Agency/LocalAgency Floodor Authoritylocal flood authority

You must also keep the following records and supplyprovide them on request:

• receipted invoices,invoices or bank statements where a receipted invoice is unavailable
• photographs of the existing site before work starts
• a copy of the Feasibilityfeasibility Studystudy, or woodland management plan or Catchmentwater Sensitiveholding Farmingstructure (CSF)action design plan (Water-Holding Feature Management Plan), where applicable
• any

Read consentsthe record keeping and permissionssite connectedvisit withrequirements in the workAgreement (inholder’s additionguide: toCapital theGrants, onesHigher statedTier above)

Pleasecapital seegrants theand recordProtection keeping and inspectionInfrastructure requirementsgrants asfor setmore outinformation.

Other initems theyou Highercan Tier,use Midwith Tierthis oritem

You Capitalcan Grantsuse guidancethis foritem morewith detail.RP11: Swales.

Advice and suggestions for how to carryhelp outyou use this item

The following advice ismay helpful,help you to use this item, but theyyou aredo not requirementshave forto follow it to get paid. It’s not part of this item.item’s requirements. 

DetailedThe design can vary and thelocation siting of leaky woody dams in natural water courses willare beaffected dictated by by:

• local circumstances andsuch availabilityas extent of tree cover, risk of riverbed or bank erosion
• whether it is to slow flood flows or to encourage groundwater recharge
• the availability of suitable materials
• easy access to import suitable materials to site.site

Using Higherthe Tiercapital Annexitem 2cFM2: hasCarry detailsout ofcustomised indicativecapital designworks ofto dams.

Checkmanage thespecific damssites or species likely more appropriate for silt

You

• sites willof needspecial toscientific checkinterest the(SSSIs)
• rivers damthat regularlyare andalready de-siltbiodiversity itpriority tohabitat preventrivers
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  become biodiversity priority habitat rivers

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• improving willsoil allowhealth
• increasing wildlifeappropriate tovegetation move/colonisecover
• using freelyrural tosustainable accessdrainage water,systems.

Checking food,the shelterdams andfor breedingsilt

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Further

Spacing information

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Small qualityleaky andwoody naturaldams

You floodcan management.use SeeRP32: guidanceSmall leaky woody dams either

• for furtherstreams informationand onriver CSFchannels support.

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