River levels online help

We publish the information about river levels so people living in flood risk areas are better informed and can decide what actions to take as the water levels change.

Anglers and boaters will also be able to use this information to check the water levels before they set off.

Read through our help guide to learn more about our river level online map, how to use its features, where our data comes from and how we use it.

Please contact us if you need any information

How do you measure river levels?

We have monitoring stations across Wales that measure water levels. Readings are stored on-site and then automatically sent back to us via our telemetry systems. 

What information is shown on the map?

River levels – measured in metres as the depth of water above a monitoring station. 

How do I find river levels near me?

You can find gauge stations near you in two ways:

1.  Using the search facility on the map page to find a location by address, postcode or monitoring station name.

2.  Using the search facility on the monitoring stations summary page to filter for specific monitoring station attributes.

How often is the information updated?

Data is recorded at 15 minute intervals, stored onsite and sent back to our systems several times a day. River level information on our website is then updated automatically. On some occasions, especially during flooding, data is retrieved more frequently.

We understand that many users would like the river level information on the website to be updated more frequently. The website is updated as soon as the data is sent from the site. There is a cost to retrieving the data from site and this is one reason why stations are not permanently connected.

Also, as many of our sites are in remote places and are powered by batteries we need to be careful how often we retrieve the data to maximise battery life and to ensure that our equipment is available to meet operational needs. 

How accurate is the data?

We work hard to provide you with accurate and relevant information. Because the measurements are sent straight to our website they are unverified and may occasionally be incorrect.

If there are persistent problems with incorrect or missing data we may temporarily suspend a site until the issues have been resolved.

Whilst every effort has been made to ensure the accuracy of the information provided, neither Natural Resources Wales, nor its employees or agents, can be held responsible for any inaccuracies or omissions, whether caused by negligence or otherwise. 

Is information available for all rivers?

We have an extensive network of monitoring stations. These stations cover all the major rivers in Wales as well as many smaller rivers and some streams and brooks. Some smaller watercourses do not have monitoring stations because we do not need to monitor them to meet our operational needs.

Are there plans to increase the number of monitoring stations?

We are always developing and improving our website and services and may be able to add more sites and information in the future. 

What do the ranges mean?

Highest Recorded - Indicates the highest recorded level within the full period of recorded data

Lowest Recorded - Indicates the lowest recorded level within the full period of recorded data

Typical Range - Indicates the usual range of water levels throughout the year. It is calculated from historical water level data collected at that gauge


Why does the river level sometimes rise or fall suddenly?

River levels rise and fall in response to how much rain falls. However, some river levels are also affected by other factors such as:

  • dams and sluices being opened and closed
  • hydropower generation
  • tides causing the river levels at some monitoring stations to periodically rise and fall
  • debris collecting in culverts


How do I receive flood warnings?

Our flood warning service can give you advance notice of when flooding from rivers and the sea is likely to happen – and give you time to prepare.

Sign up for Floodline Warnings Direct 

I have an abstraction license, can I use this information?

The river level data on our website is un-validated and should not be used by abstractors to meet specific conditions of their licence.

If you would like further information contact our Customer Care Centre or find out how to make a request for information

Why does the website use Greenwich Mean Time (GMT) rather than British Summer Time (BST)?

We have used Greenwich Mean Time as this is the standard method for collecting hydrometric data. 

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