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Public consultation on the designation of heavily modified waterbodies for the third cycle River Basin Management Plan
The purpose of this consultation is to seek your views on the designation of heavily modified waterbodies, and the review process that has been conducted to feed into the final river basin management plan for 2022-2027. The consultation period has been extended and now closes on 15 May 2022. The EPA will review the outcomes of the consultation process and make a recommendation to the Minister for Housing, Local Government and Heritage on the waterbodies that meet the designation criteria. The Minister will consider the recommendation and make a decision on the designations, which will then be published in the final river basin management plan.
Heavily modified waterbodies are surface waterbodies that have had their physical characteristics, or hydromorphological conditions, modified by engineering works for the purposes of one or more specified uses. These uses include power generation, water supply, flood defences, arterial drainage, navigation, or urban environments. Heavily modified waterbodies are formally designated by the Minister for Housing, Local Government and Heritage as part of the river basin management plan making process.
To help prevent further deterioration and to protect and enhance heavily modified waterbodies, they are given an Ecological Potential environmental objective under the Water Framework Directive, rather than an Ecological Status objective.
An Ecological Potential objective recognises that the modifications may prevent some biological quality elements from achieving Good Ecological Status. For example, large dams associated with drinking water supplies may prevent the free passage of fish, which may impact on the structure and diversity of fish populations, and therefore on the status of fish.
To achieve Good Ecological Potential, the standards for all the other Water Framework Directive elements such as nutrients, chemicals and any other biological elements that are not impacted by the modification must still be achieved. Measures must also be implemented to mitigate the impacts of the modification as much as possible, and to an extent that does not have an adverse effect on the specified use. In the case of a large dam, the mitigation measures may include the installation of a fish pass and the implementation of an appropriate environmental flow regime through the dam. Heavily modified waterbodies will not have met their Water Framework Directive objectives unless the measures are in place and the monitoring shows that water quality is otherwise satisfactory.
Recent European (CIS) guidance, designed to provide better clarity for Member States on the designation process, has made it clear that a heavily modified waterbody designation is not an exemption, a derogation, or a lower objective, and does not consign a waterbody to abandonment. Rather, it allows realistic environmental objectives to be set that maintain the highest ecological standards possible given the specified use. The requirement for mitigation measures to be implemented as part of the classification of ecological potential also ensures a level of transparency and accountability so that the best possible environmental outcomes are being achieved.
The heavily modified water body designation review process is for the purposes of assigning environmental objectives for the third cycle in the context of current legislation and policy. Designations will be reassessed in the next planning cycle. Other specified uses can also be considered (e.g. recreation) while other water bodies within the current specified use categories can be considered for inclusion depending on data availability (e.g. river water bodies within drainage district schemes).
How is a heavily modified waterbody designated?
For the first river basin management plan, Ireland designated a small number (33) of heavily modified waterbodies, the lowest number of all member states. The designations were based on EU Guidance, but were limited by the available data and evidence at that time. The second cycle river basin management plan tasked the EPA with carrying out a review as part of the national hydromorphology work programme. The review commenced in 2020 and was carried out with the assistance of the National Hydromorphology Working Group.
The heavily modified waterbody designation process is a technical, structured, 11-step assessment, that is set out in European guidance1,. The steps can be broadly divided into three high level sets of tasks: the characterisation tests, the designation tests, and the assessment of Ecological Potential.
The characterisation tests assess the extent, significance and impact of the physical modifications of each waterbody and their impact on Ecological Status. These tests have been carried out using new hydromorphological assessment tools that have been developed by the EPA over the last number of years. These include the Morphological Quality Index for Ireland (MQI-Ireland) for rivers, Lake-MImAS for lakes, and TraC-MImAS for transitional and coastal waters.
The designation tests are carried out based on the guidance and information provided by the specified use owners, including for example, Waterways Ireland for navigation, Irish Water for drinking water supply, ESB for power generation, local authority representatives to address the urban environment and OPW for arterial drainage and flood mitigation. An assessment was made of whether candidate heavily modified waterbodies could achieve an Ecological Status objective if measures were implemented, but without impacting on the specified use. Consideration is also given to whether the specified use can be achieved by another means that is a significantly better environmental option, and that is technically feasible, and not disproportionately costly.
The assessment of Ecological Potential establishes the environmental objective for each heavily modified water body, and then assesses its current condition compared to that objective. The EPA is currently developing an approach to setting and assessing Ecological Potential, based on the most recent EU guidance2. The approach is based on evaluating if the best practice mitigation measures are in place, and the standards for the other WFD monitoring programme elements not impacted by the modification (such as nutrients and chemical pollutants) are being met. A comprehensive library of measures has been developed as part of the EU guidance to assist member states in determining which mitigation measures are considered best practice for each specified use.
Further details on the designation process are outlined in the technical review available for download below.
Two case studies which illustrate the application of the heavily modified water body designation process are available within the attached review. The first is for three heavily modified waterbodies in the Lower Shannon system that are impacted by power generation and water supply. The second is for three heavily modified waterbodies in the Moynalty River that have been modified by the Boyne arterial drainage scheme.
How many waterbodies are proposed for designation?
The review has identified that the number of waterbodies that meet the criteria for designation as heavily modified waterbodies has increased significantly. An additional 430 rivers, four lakes and two transitional and coastal water bodies were identified as heavily modified water body candidates for designation in the third river basin management plan for the period 2022-2027. This will bring the total number of designations in Ireland to 466 (433 rivers, 20 lakes and 13 transitional and coastal water bodies). One river water body (Bregagh (Kilkenny)_030) has been de-designated as it no longer meets the criteria for heavily modified water body designation since the first cycle (i.e. designated in the first cycle due to a contamination event that required localised dredging/introduction of artificial material). The largest increase has occurred in rivers that have been modified, where the most common modification is due to arterial drainage. The breakdown of specified uses within all heavily modified waterbodies are presented in Table 1. The list of heavily modified water body candidates for the third river basin management plan are available for download below.
Why has the number of designations increased?
This significant increase is due to a number of factors. In the first cycle, as this was a new concept, there were limited data, assessment tools and methods available, nationally or internationally. Arterial drainage was not included in the first cycle assessment for example, due to the lack of relevant data.
There was also limited experience or understanding of the heavily modified waterbody designation process in Member States, and the consequences of designation were poorly understood. There was a concern that a designation would result in the effective downgrading of a waterbody, and that it would no longer be considered eligible for, or worthy of, mitigation measures. A very conservative approach was therefore taken in Ireland to keep the number of designated waterbodies as low as possible until such time as knowledge and understanding improved.
However, as highlighted above, recent European (CIS) guidance has made it clear that a heavily modified waterbody designation is not an exemption, a derogation, or a lower objective and does not consign a waterbody to abandonment.
Closest Waterbody Type
|1st and 2nd Cycle
Number of waterbodies
| 1st and 2nd Cycle
|3rd Cycle Review
Number of waterbodies
|3rd Cycle Review
|Flood protection (2)
Water storage – drinking water / hydropower (1)
Wider environment (localised dredging/ introduction of artificial material to mitigate a contaminant spill) (1)+
|Arterial drainage (325)
Flood protection (64)
Water storage and regulation (drinking water supply/hydropower) (29)
Urban environment (23)
|Water storage – drinking water / hydropower (16)
|Water storage – drinking water / hydropower (20)
|Transitional and Coastal waters
|Ports and harbours (10)
Railway crossing (1)
|Navigation (10) §
Urban (3) §
*Some river waterbodies have multiple specified uses so the numbers don’t add up to the total.
+ River waterbody has now been de-designated for Cycle 3.
++ Note that two of the 33 HMWBs include Newry Estuary and Foyle and Faughan Estuaries. These are cross border HWMBs monitored by the Northern Ireland Environment Agency and therefore are not included in this review.
§ Navigation and urban are the comparable specified uses for ports/harbours and railway crossings, respectively, for the third cycle.
All documents can be downloaded from the EPA website:
Why are we consulting with you?
The purpose of this consultation is to seek your views on the designation of heavily modified waterbodies, and the review process that has been conducted to feed into the final river basin management plan for 2022-2027. Please forward any comments you may have to firstname.lastname@example.org
The consultation period has been extended and now closes at midnight on 15 May 2022.
The EPA will review the outcomes of the consultation process and make a recommendation to the Minister for Housing, Local Government and Heritage on the waterbodies that meet the designation criteria. The Minister will consider the recommendation and make a decision on the designations, which will then be published in the final river basin management plan.
 European Union Common Implementation Strategy (CIS) guidance (No. 4)
 The National Hydromorphology Working Group is a subgroup of the National Technical Implementation Group. Its membership comprises representatives from public bodies with expertise or interests in hydromorphology such as OPW, IFI, Local Authorities, LAWPRO, Waterways Ireland and Irish Water. Both groups are part of the WFD governance structures and are chaired by the EPA.
 European Union Common Implementation Strategy (CIS) guidance (No. 37)