Catchment News

Go with the flow, keep it on the level: measuring water quantity in Ireland’s rivers, lakes and groundwaters

The EPA recently launched a monthly hydrometric bulletin which will provide a national summary of river flow, lake and groundwater levels across Ireland. Conor Quinlan tells us about the work of the EPA Hydrometrics and Groundwater team and how their data underpins assessments of change…

The EPA Hydrometric and Groundwater section operate a network of over 350 surface water and groundwater water level and flow monitoring stations across Ireland. These stations produce time series data for river and spring flows and lake and groundwater levels which provides a nationally representative sample of water flow and level conditions. These data sets are used to calibrate models and applications for water resource management and assessment, to ensure flows are sufficient to support healthy aquatic ecology, climate change impact and adaptation, and to support the licencing and enforcement work of the EPA.

Measuring flow in a river.

If we use the human body as an analogy for monitoring and assessing the health of our aquatic ecosystems, physio-chemical (i.e. water quality) test results are like blood test results, while hydrometric information including river flows, spring flows, groundwater levels, and lake levels correspond to the heart rate and blood pressure readings of a person.

Like a medical assessment, both water quality (blood test results) and hydrometric information (pulse and blood pressure) are required to accurately assess and diagnose issues in our aquatic ecosystems.

Flow and level data are a vital component required to achieve integrated catchment management. Water quality results must be combined with flow information for us to calculate what volume or load of contaminant is present, the spatial extent of contamination, the speed at which it moves though a system and where it ends up. Flow and level information is also vital for us to sustainably manage abstractions and discharges from and to our surface waters and groundwaters.

A remote-control boat: this is used to measure flow and to map
the river channel profile.

Representative long-term flow and level records are also vitally important to enable us to identify climate driven changes in our aquatic ecosystems and to ensure that climate adaptation planning is evidence-based and proportionate. Climate predictions and hydrological models derived from them are estimates of future conditions in our catchments. Like all models, these predictions are unlikely to be entirely accurate in many locations. It is therefore vital that we maintain monitoring networks to obtain high-quality records of actual measured changes in hydrological flow and level conditions across Ireland in the coming years and decades. These observations will be used to assess and re-calibrate climate models and to provide an evidence-base for the sustainable future management of our waterbodies.

Flow and level information is used together with abstraction and discharge data to assess and manage the water resources in our waterways on a truly cumulative basis. This integrated approach is key both to enable us to achieve the environmental objectives for our waterways and to utilise and protect our combined surface water and groundwater resource in an uncertain future where both increased flooding and more frequent droughts are predicted to occur.

Flow and level data are available for download via the EPA HydroNet web portal. River flow percentile estimates for catchments where there is no hydrometric monitoring station can be viewed on EPA Water Maps in the ‘River flow estimates – HydroTool’ layer.

The National Register of Hydrometric Stations in Ireland is available for download from the EPA website.

The EPA has also launched hydrometric bulletins which will provide a monthly national summary of river flow, lake and groundwater levels across Ireland.

Conor Quinlan, EPA Hydrometrics and Groundwater Section

Learn more:

Monthly Hydrometric bulletins: flows/hydrometricbulletins/


EPA Water Map:

The EPA Hydrometrics and Groundwater team.

Who is involved?

Quite simply, everyone in Ireland has a role to play. This can be from something as simple as making sure you don’t pollute your local stream, or a local community working together to establish a Rivers Trust to enhance the rivers and lakes in their area, to a Government Department or Agency helping a Minister implement a new policy to help protect and enhance all our water bodies.

This website has been developed and is maintained by the Environmental Protection Agency, and is a collaboration between the Department of Housing, Planning and Local Government, the Environmental Protection Agency, and the Local Authority Waters Programme.


Local Authority Waters Programme

The Local Authority Waters Programme coordinates the efforts of local authorities and other public bodies in the implementation of the River Basin Management Plan, and supports local community and stakeholder involvement in managing our natural waters, for everyone’s benefit.


Environmental Protection Agency

The EPA is responsible for coordinating the monitoring, assessment and reporting on the status of our 4,842 water bodies, looking at trends and changes, determining which waterbodies are at risk and what could be causing this, and drafting environmental objectives for each.


Department of Housing, Local Government and Heritage

The Department is responsible for making sure that the right policies, regulations and resources are in place to implement the Water Framework Directive, and developing a River Basin Management Plan and Programme of Measures to protect and restore our waters.