Significant increase expected in water bodies designated as ‘heavily modified water bodies’
Up to 466 water bodies throughout Ireland could be designated as heavily modified water bodies (HMWBs) in the next River Masin Management Plan 2028-2033.
This proposed designation follows a comprehensive technical assessment by the Environmental Protection Agency (EPA) in 2022 and reflects a significant evolution in the State’s approach to water resource management.
Previously, only 33 water bodies had been designated as HMWBs. The expansion to 466 water bodies comprises 433 rivers, 20 lakes, and 13 estuarine or coastal waters.
The expanded candidate list reflects recognition that significant hydromorphological alterations have historically occurred to support specified uses.
Under the EU Water Framework Directive (WFD), HMWBs are those whose physical characteristics have been significantly altered for a specified use, making the achievement of Good Ecological Status (GES) impractical without causing disproportionate socioeconomic or environmental harm. Instead, these water bodies are assessed against the alternative objective of good ecological potential (GEP).
The Department’s review, informed by additional data from specified use owners, determined that in all 466 cases, achieving GES would either “compromise vital services” or prove “technically or financially unviable”. These findings are designed to ensure that the RBMP’s objectives remain aligned with both environmental goals and Ireland’s infrastructural realities.
Going ahead, HMWBs must be integrated into regulatory, planning, and licensing frameworks. The EPA has proposed defining and monitoring GEP targets using the Mitigation Measures (Prague) Approach, emphasising improvements where feasible while safeguarding critical human uses.
The designation will be revisited in future planning cycles as national policy evolves particularly in areas such as arterial drainage, land use, and flood management, and as ecological assessment tools become more refined.
The public consultation on the designation of Heavily Modified Water Bodies closed on 23 May 2025, following an eight-week period for stakeholder engagement.
Planning for the fourth-cycle RBMP (2028-2033) is underway, with a public consultation having closed for submissions on 25 July 2025.
This article was updated on 26 August 2025 to reflect an error in designation of a source.
