Consent Requirements – Construction/Alteration of Watercourse Infrastructure

From Office of Public Works 

Published on 9 January 2018

Last updated on 24 March 2022

  1. Introduction
  2. Restrictions on the Construction or Alteration of Bridges and Culverts
  3. Modification or Relocation of Watercourse, Embankment or Other Works
  4. Restrictions on the Erection/Alteration of Weirs
  5. Further Information and Forms


The OPW seeks to maintain the existing conveyance and storage capacities of channels and floodplains. The design and construction of bridges and culverts should be such that flood risks up- and / or down-stream are not increased, or, where no other viable options exist, are restricted to acceptable levels, and should comply with any flood risk management objectives and plans established for the area.

Restrictions on the Construction or Alteration of Bridges and Culverts

Section 50: Arterial Drainage Act, 1945 The consent of the Commissioners is required by bodies and persons proposing to carry out construction/alteration works on bridges and culverts.

Modification or Relocation of Watercourse, Embankment or Other Works

Section 9: Arterial Drainage Amendment Act, 1995 The Commissioners may consent to alterations to existing watercourses or structures in Drainage Schemes if the proposed works would not increase the risk of flooding or have a negative impact on drainage of land. This section applies to regrading or relocation of watercourses, replacement or relocation of embankments and various other works on Drainage Schemes. Applications under this section are dealt with on a case by case basis, and applications should be addressed to the appropriate OPW regional office.

Restrictions on the Erection/Alteration of Weirs

Section 47: Arterial Drainage Act, 1945 Any person planning to erect or alter a weir must first get consent from the Commissioners or all the affected landowners. The Commissioners may grant consent only where the applicant meets stringent requirements. The ESB is exempt from this requirement as a separate statutory process is in place.

Further Information and Forms

Image: None

Section 50 brochure



Image: None

Section 50 Application Form – PDF



Image: None

Section 50 Application Form – Word


AIE 4/4/23

Under the AIE Regs to request copies of

1) all Section 50s granted

2) all Section 50s refused

3) all Section 9s granted

4) all Section 9s refused

5) all Section 47s granted

6) all Section 47s refused

Please include the initial Application Form AND the OPW documents granting/ refusing the consent

For the purposes if this AIE, please consider the years 2021, 2022 and 2023 to date

For the purposes of this AIE, active disclosure via publication of consents on or similar will suffice

West Cork Flood Relief Schemes

Non-Return Valves

• River Ilen (Skibbereen) Flood Relief Scheme (also known as the Skibbereen FRS)
• River Bandon Flood Relief Scheme (also known as the Bandon FRS)
• Clonakilty Flood Relief Scheme (also known as the Clonakilty FRS)

These schemes were built under the OPW powers of the Arterial Drainage Acts 1945 & as amended in 1995.
The above schemes are now in the Operation & Maintenance (O&M) phase.

Environmental Consultancy Services for The OPW National Arterial Drainage Maintenance Activities


The Office of Public Works (OPW), Arterial Drainage Maintenance Service is commissioning an environmental consultant to assist with various environmental services, to support arterial drainage maintenance activities on twenty six arterial drainage schemes.

Part 1
The principal study area for Part 1 of the Commission makes up twenty six schemes for arterial drainage schemes and flood relief schemes.

The contract will require the completion of AA Screening for 26 Schemes and it is assumed that 21 of these schemes will require an NIS. Reporting is to be completed over the next 3 year period.

The AA Screening Reports and NIS for the twenty six schemes will be carried out in assigned years as follows:

Year 1 (2023): Abbey, Bonet, Boyle, Broadmeadow & Ward, Brosna, Donegal Schemes, Feale, Knockrockery, Lower Shannon Schemes, Maine, Hazelhatch, Matt.

Year 2 (2024):Ballyteigue/Kilimor, Corrib, Duff, Inny, KIlcoo, Killimor/Cappagh, Ouvane, Monaghan Blackwater.

Year 3 (2025):Boyne, Duleek, Mornington, Moy, Ryewater, Owenavorragh.
Completion of the AA Screening and NIS’s for each year includes assessing the impact of the work and providing field data as described in Part 2 below.

Part 2
The OPW have identified lengths of channel that a Rapid River Corridor Survey should be completed. The lengths of channels identified are the channels within and 100m upstream and downstream of the boundary of the European Sites for which AA Screening and NIS is programmed for in that year.

The Rapid River Corridor Survey includes approximately 1660km of channel to be carried out over a three year period.

Part 3
Further to the above the consultant may be asked to carry out further surveys within the 3 year period.

Additional information

Further details will be provided in the tender documents which will be issued with the Request for Tender in due course

Estimated date of publication of contract notice:


Reports on Bride River (Various)

Cork Corporation. Glen, Bride and Kiln River Improvement. Preliminary Report 1982 Vol 1 & 2

Blackpool Retail Park Flood Study

City Council and OPW flood report 2012

2013 Trash Screen report (best document on Blackpool Flooding with lots of useful information

Cork Nature Network Otter Report 2022

Camera Trapping – Quality of data collected through the use of camera traps at a number of sites frequented by otters within Cork City

The Otters of Blackpool

Glen, Bride and Kiln Review (2003)

King’s Island Flood Relief Scheme: Vegetation Site Clearance / Tree Felling Works

Tender for vegetation clearance in advance of the King’s Island Flood Relief Scheme (Limerick)

Limerick City and Council is undertaking vegetation clearance in advance of the King’s Island Flood Relief Scheme. The project involves vegetation clearance of an area of approx. 4560m2 and the removal of approximately 39 trees at locations around Kings Island in Limerick

Multi-Party Framework Agreement for the preparation of Surface Water Management Plans (SWMP) for Fingal County Council

To establish a Multi-Party Framework for Engineering Consultancy services for the preparation of Surface Water Management Plans (SWMP) for Local Area Plans (LAP), Masterplans, Urban Frameworks and other study areas;

Surface Water Management plans will consist of two key integral parts;

1. Preparation of Strategic Flood risk assessments in accordance with the “Planning system and Flood risk Management Guidelines for Planning Authorities”. This will include for all relevant stages of flood risk assessment as outlined by the Guidelines. 

2. Preparation of Sustainable Drainage Strategies (SDS) for the sustainable development of lands under consideration for development. The strategies will be an example of best practice in the use of sustainable drainage systems (SuDS)/Nature Based Solutions. As set out in the Fingal County Development Plan, it is an objective of Fingal County Council to encourage, promote and implement sustainable drainage systems (SuDS) on all new developments throughout the county and to encourage where feasible the retrofit of sustainable drainage systems within existing developments. The Sustainable Drainage Strategy will examine the feasibility of using all SuDS solutions including, swales, permeable pavement, rainwater harvesting, tree pits, green and blue roofs, detention basins, ponds and wetlands amongst other SuDS devices. The SDS must comply with the Fingal County Council Green Blue Infrastructure Guidance and the Dept of Housing Nature Based Solution Guidance 2022.