02-08-2025
Project Reveals Impact on Rivers of Long Term Peatland Drainage
The UCD study for EPA focuses on the quality of streams in the midlands.
A project has revealed how long-term peatland drainage for extraction and other land uses has negatively impacted Ireland's rivers and streams.
The project, Strategies to Improve Water Quality from Managed Peatlands (SWAMP), was prepared by University College Dublin (UCD) for the Environmental Protection Agency (EPA).
It aimed to address key knowledge gaps about water quality degradation in Ireland's peatland areas.
This study presented a snapshot of the quality of streams in the Irish midlands, a region known for its historical expanse of raised bogs, most of which have been affected by peat extraction.
Water quality degradation has been caused by "decades of drainage for industrial and domestic peat extraction", according to the researchers.
Drained peatlands have leached harmful nutrients, acids, and carbon-rich water into streams, the research found.
According to the report: "The research identified some protected peatlands that also had poor water chemistry, highlighting the widespread legacy effects of drainage.
"Aquatic biota in degraded bogs showed reduced biodiversity, although downstream effects were linked to upstream water quality, not bog status alone, underscoring the need for site-specific ecological indices to assess peatland restoration projects.
"While sedimentation ponds at the edge of a cutaway bog removed suspended solids, this approach failed to treat dissolved pollutants, with seasonal acidity and nutrient surges further violating ecological standards.
"Edge-of-field treatments with biochar showed inconclusive results, warranting further study."
The researchers said that the full impacts of continued peat extraction must be acknowledged and properly assessed ahead of proposed land use, energy, and horticultural projects that all require drainage.
"If licensing activities are sought for continued peat extraction in Ireland, stricter regulations and associated monitoring must be implemented, updating licence thresholds to reflect regional needs," the report said.
This research focused on identifying pollution hotspots, measuring the effects of peat soil drainage on water chemistry and aquatic biodiversity, assessing pollution prevention measures, and developing better hydrological models to predict the response of peatlands to drainage and restoration.
"The SWAMP project's findings arrive at a critical time, as Ireland needs to address the specific challenges of achieving compliance with the EU Water Framework Directive and delivering on the Nature Restoration Law," according to the researchers.
"Reversing centuries of unsustainable peatland management and the declining trend in water quality in streams in the midlands will require considerable effort from all stakeholders.
"It will require the coordination of multiple agencies to expand the monitoring of peatlands both in space and time and in particular to include water quality indicators at site and regional levels."
The report outlines how Ireland's water quality "continues to decline, driven partially by peatland drainage for agriculture, forestry and industrial extraction".
"These disturbances alter peatland hydrology and biogeochemistry, exacerbating downstream pollution, flood risks and carbon/nutrient losses – pressures that are all intensified by climate change."
The report outlines how tackling the pollution recorded in bog streams at specific sites will be largely addressed by rewetting and rehabilitation projects within existing drained bogs, and stricter legal requirements for the treatment of effluents associated with peat extraction activities.
There is a need for "tailored, site-specific" approaches rather than a "one-size-fits-all", the report said.
"Success hinges on interdisciplinary collaboration to address compounding pressures, from legacy drainage impacts to climate change," the researchers added.
The Draft River Basin Management Plan for Ireland 2022–2027 indicates that 106 surface waters are currently impacted by peat extraction and drainage, the report notes.
"This situation prevents Ireland from fully complying with the EU Water Framework Directive," according to the new report.
"It is critical to understand the pressures on waters arising from degraded peatlands.
"Appropriate regulatory measures and innovative technologies must be developed to ensure that the status of water bodies is protected, maintained and improved in line with the requirements of national and international environmental standards."
The final recommendations of the SWAMP project include that immediate actions are needed to "target nitrogen pollution hotspots with effective treatment solutions and stricter effluent regulations".
Long-term strategies are also key, to "prioritise large-scale rewetting of drained peat soils, coupled with long-term monitoring to track recovery".
The project has also highlighted research gaps, and the need to "develop standardised peatland models, improve biogeochemical process representation and refine ecological assessment tools".
"Reversing water quality declines in the midlands will require decades of coordinated restoration and rewetting of degraded peatlands," the researchers said.
"The SWAMP project's integrated findings underscore the need for adaptive, multidisciplinary management – supported by flexible funding – to address peatland-specific complexities amid climate change."
The report recommends stricter water quality controls to be included and regulated as part of the licensing of peat extraction activities.
"The water protection methods must be clearly validated at each specific environmental location in combination with specific regional objectives," the report states.
"The monitoring of data must also take cognisance of seasonal effects and additional site-specific factors, which may influence 'key' nutrient species.
"In addition, action must be taken to address water pollution from the activities of unlicensed small private peat companies, as well as from bogs affected by domestic turf-cutting, which impact an even greater land surface area."
It is also recommended that large-scale rewetting of extracted bogs must be accompanied by long-term monitoring of the chemistry of the bog water and receiving streams.
"Reducing pollution from drained bogs will be largely addressed by restoration and rehabilitation projects that affect not only Bord na Móna bogs but also privately-owned bogs within a catchment."
Revised mitigation measures to treat effluent waters from not only extracted bogs, but also all sites that include drainage of peat soils (land use change, wind farms) must be implemented, the researchers have recommended.
The report states that "rewetting of all peat-extracted sites is necessary to reduce the high nitrogen and carbon losses in freshwaters".
"Our results suggest that more efficient and varied treatment processes are needed to help improve and future-proof water quality from peaty catchments."
