Check dams slow the movement of water in ditches, swales and surface water pathways. They slow surface water, allowing sediment and other pollutants to settle to the bottom. They help to improve water quality and reduce downstream flooding and support water resources. Leaky wooden dams are typically used to deliver water resource benefits.
This item can help you protect, recover and improve biodiversity on your land.
Where you can use this item
You can use this item on ditches, swales, and water surface pathways with a feasibility study (that you’ll do before you apply) or the Catchment Sensitive Farming water holding structure action plan you have produced with Natural England either:
in areas targeted to reduce water pollution from agriculture
to reduce flood risk
to improve recharge of groundwater – where permeable soils and geology allow for the capture and storage of groundwater
Catchment Sensitive Farming provides advice where there are water quality or flood risk issues linked to farming.
You must follow the requirements set out in your feasibility study or Catchment Sensitive Farming water holding structure action plan.
Evidence you must keep
You must keep and provide with your claim:
photographs of the site during the different stages of construction or contracts, invoices or other documents confirming the technical specification for the completed works
photographs of the completed works
You must also keep and provide on request:
any consents or permissions connected with the work
receipted invoices or bank statements where a receipted invoice is unavailable
photographs of site before works start
a copy of your feasibility study or Catchment Sensitive Farming water holding structure action plan
The following advice may help you to use this item, but you do not have to follow it to get paid. It’s not part of this item’s requirements.
Using several dams
It’s likely you’ll need several dams to manage water flows successfully. On ditches, use a series of multiple dams that are between 5 to 7 times wider than the channel. This prevents woody debris becoming dislodged during floods.
Checking the dams for silt
Check the dam and de-silt it regularly to prevent it collecting large amounts of silt.
Designing and constructing the dam
You’re likely to need to:
construct the dam from local soils with a high clay content, timber or stone (as appropriate to the local landscape)
excavate a trench 200 millimetres (mm) deep across the width of the channel, swale or flow pathway
build up the check dam using 100mm to 600mm grade broken stone, wooden boards, gabions, or earth to a height of 500mm to 750 mm above the floor of the swale
build the check dam at the down slope end of the trench and leave the upslope end of the trench empty
make sure side slopes of the check dam are a gradient 1 in 2
build check dams into the sides of the channel, swale or flow pathway to avoid water bypassing the structure
protect at least 1 metre (m) to 2m downstream to dissipate energy from the dam
place an overflow in the centre of the dam to prevent any scouring of the ends of the dam
Amended item - you can now use this item:
- to reduce flood risk
- in catchments where permeable soils and geology allow for the recharge of groundwater
31 January 2021
Added in links to Capital Grants manual as this option is now available for Capital Grants