Catchment News

Hydrology Summary Bulletin – December 2022

The Hydrology Summary Bulletin for December 2022 has information on the flows in rivers, rainfall, lake levels, groundwater levels and spring outflows of over 300 stations across Ireland. Rainfall was below the long-term average in most of Ireland last December. River flows, lake and groundwater levels were mostly normal (though some were low) for this time of year.


Rainfall was below the long-term average in most places this month. Similarly, monthly average river flows were below the long-term average in most rivers across the country, with over half (58%) of river monitoring sites in the normal range and a further 37% below normal for December. Average lake levels also fell during December, with over half (57%) of lakes in the normal range and almost one-third (32%) of lakes with levels below normal for this time of year. There is a similar observation for average monthly groundwater levels, with falling levels since November. Just under half (48%) of monitoring wells were in the normal range for December with a further 36% of wells below normal. Most monitored spring outflows were normal or below normal for December.


The majority of monthly rainfall totals across the country were below their 1981-2010 Long-Term Average (LTA). Percentage of monthly rainfall values ranged from 71% (monthly rainfall total of 93.0 mm) at Finner, Co Donegal to 136% (the month’s highest monthly rainfall total of 187.1 mm) at Belmullet, Co Mayo. Monthly rainfall totals were lowest at Oak Park, Co Carlow with 68.0 mm (81% of its LTA). The month’s wettest day was also recorded at Belmullet, Co Mayo with 41.3 mm on Christmas Day, Sunday 25th . The number of rain days ranged from 15 days at Oak Park, Co Carlow to 28 days at Malin Head, Co Donegal. The number of wet days ranged from 9 days at Ballyhaise, Co Cavan to 22 days at both Malin Head, Co Donegal and Belmullet, Co Mayo. The number of very wet days ranged from 2 days at a few stations to 8 days at Newport, Co Mayo.

River flows

Average river flows for December fell at 91% of monitoring stations compared to average flows observed in November. The monthly average flows at 156 river monitoring sites across the country identified; 1 (1%) as ‘particularly high’ [Glencastle, Co. Mayo], 6 (4%) as ‘above normal’, 90 (58%) as ‘normal’, 52 (33%) as ‘below normal’ and 7 (4%) as ‘particularly low’ for this time of year.

A map of Ireland showing river flows for December 2022. Most dots are green an yellow, meaning flows are normal or below normal , there are a small number of red dots for low flows
Monthly average river flows for December 2022 relative to historic monthly average flows expressed as percentile of the long-term values of monthly flow.
All data are provisional and may be subject to revision (Source: EPA, OPW).

Lake and turlough levels

Average water levels for December fell at 84% of monitored lakes compared to average levels for November. Analysis of monthly average levels at 40 lakes and 4 turloughs were classified as ‘particularly high’ at 3 (7%), ‘above normal’ at 2 (4.5%), ‘normal’ at 25 (57%), ‘below normal’ at 12 (27%) and 2 (4.5%) of monitoring locations for the month of December.

A map of Ireland showing lake and turlough levels in December 2022 - most are showing green for normal levels for this time of year.
: Monthly average lake levels for December 2022 relative to historic monthly average levels expressed as percentile of the long- term values for this month.
All data are provisional and may be subject to revision (Source: EPA, OPW and GSI).

Groundwater levels and spring flows

Average groundwater levels in December fell at 73% of monitoring wells compared to average levels observed in November. December groundwater levels at 42 monitoring locations were classified as ‘particularly high’ at 1 well (2%) [Clarabog. Co. Offaly], ‘above normal’ at 6 wells (14%), ‘normal’ at 20 wells (48%), ‘below normal’ at 11 wells (26%), and ‘particularly low’ at 4 wells (10%) across the country.

Spring outflows were also monitored at 8 EPA monitoring sites for December. The outflows from these springs were compared to previously recorded flows for December and were ‘normal’ at 2 locations, ‘below normal’ at 5 locations and were ‘particularly low’ at 1 [Rockingham Co. Roscommon] monitoring spring location for this time of year.

A maps of Ireland showing spring outflows and groundwater levels for December 2022. Most are normal or below normal.
Groundwater level and Spring Flow status for December 2022, relative to historic monthly groundwater levels.
All data are provisional and may be subject to revision (Source: EPA).

Learn more:

The monthly hydrology bulletin can be downloaded here:–assessment/freshwater–marine/hydrology-bulletin/hydrology-bulletin/

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.