Measuring water levels and flow

The EPA monitors river flows and the water levels of our rivers, lakes and groundwater (wells and springs). It does this by operating a hydrometric network of over 350 surface water and groundwater monitoring stations in the Republic of Ireland, as part of the National Hydrometric Programme.

Other bodies also monitor water levels and flow:

  • Office of Public Works (OPW) measures river flows and river and lake water levels in relation to flood management and protection. Further information is available from the OPW on the flood risk management plans and the activities of the Shannon catchment flood risk management group.
  • Waterways Ireland monitors and manages the water levels and flows in our canals.
  • ESB monitors and manages the water levels and flows associated with our hydroelectric dams.
  • Marine Institute monitors sea-level fluctuations around our coasts.

Long-term water level monitoring is also undertaken by institutions such as the Geological Survey of Ireland and Irish Water. It may be carried out in relation to specific activities (e.g. by industry in relation to licence conditions) or for research (e.g. by the agricultural research institute Teagasc).

Why do we monitor water levels and flow?


Collecting data on water level and flow helps us provide evidence-based information on how to manage our water resources and protect these now and into the future.

Information on water levels and flow is used to:

  • Decide how much water we can safely take for drinking water, from a river or lake
  • Tell us how much wastewater can be safely released into a river or lake
  • Design infrastructure such as bridges
  • Help us understand where and how much pollution is entering our waters
  • Monitor long-term trends for flooding and climate change assessments
  • Help people to plan their activities on water (e.g. boat navigation, fishermen and canoeists)

What is the Hydrometric Programme?

The Hydrometric Programme is a national programme for the collection, analysis and distribution of data on water quantity. The EPA is required to prepare this programme by the Environmental Protection Agency Act (1992).

Hydrometric data gathered by this programme include flows and water levels of rivers and canals, lake water levels, groundwater levels (and flow from springs) and water levels in the sea.

The Hydrometric Programme is carried out with co-operation between:

Working together with the organisations above ensures an efficient service to the various local authorities, government agencies, consultants, private industry and the public.

The EPA reviews the Hydrometric Programme and the hydrometric network every five years. You can download the National Hydrometric Monitoring Programme 2022-2027.

What is the hydrometric network?

The hydrometric network consists of over 1,000 active monitoring stations in the island of Ireland operated by the organisations listed above. Over 350 are operated by the EPA in conjunction with local authorities and the remaining ones are operated by the other organisations listed above.

The hydrometric monitoring stations are positioned along surface waters (rivers, lakes, canals, and estuaries) and in groundwaters (spring and wells). You can access all collected and summary data for each station on our water level and flow data page.

The EPA also maintains the register of all hydrometric stations in Ireland. It includes all active and historical hydrometric monitoring stations for surface water and spring sites.

What is a hydrometric station?

Staff gauge at hydrometric station

Hydrometric stations in surface waters, such as river and lakes, are commonly known as gauging stations. They can be placed in natural river sections or purpose-built structures such as weirs. Hydrometric stations in groundwater consist of both wells and springs.

At a minimum, each station is fitted with a staff gauge, which is a graduated scale to indicate water level. Most of our stations are fitted with telemetric water level records that monitor the water level every 15 minutes and transmit data to the EPA every few hours.

Learn more

Find out more on how we measure river level and flow in a river.

Find out more on groundwater.


National Hydrometric Monitoring Programme Cover
National Hydrometric Monitoring Programme 2022 - 2027

The National Hydrometric Programme sets out the hydrometric monitoring that will be undertaken by various public authorities in Ireland in the period 2022-2027.

Learn more about what we do inside the EPA