River Monitoring

River water quality monitoring in Northern Ireland is carried out by our Water Management Unit (WMU) to manage the aquatic environment in a sustainable manner. We are committed to chemical and biological monitoring of all significant waterways in NI in line with national and international classification schemes and agreements.

A major review of the network undertaken in 1999 defined the objectives of the routine river monitoring programme:

• To classify general river water quality using the appropriate national chemical and biological schemes
• To assess compliance with specific directives and international agreements
• To provide the river quality information required for the setting of effluent discharge consent standards.

Other investigative monitoring programmes are required to determine causes of pollution where it occurs or to monitor the effects of management activities.

The review led to the closure of a number of routine monitoring stations because:

• they were affected by known effluent discharges and therefore not representative of general river water quality, or
• statistical analysis of results showed that they were surplus to requirements as the information they were providing could be obtained from neighbouring stations.

Following assessment of the rationale underlying other river monitoring networks in Great Britain and the Republic of Ireland, it was decided that rivers with a mean daily flow of at least 5000 m³ per day should be considered for inclusion in the NI network. Some rivers were excluded from the network because they were either very small with minimal flow in summer, unsuitable for effective sampling or for Health and Safety reasons related to access.

The review more than doubled the number of biological sampling stations and increased the length of rivers monitored from around 2400 km to more than 5000 km. The larger rivers that were being monitored prior to the review were categorised as 'primary'. Those added to the network were categorised as 'secondary' (smaller rivers at least 3 m wide) or 'minor' (smaller rivers from 1.5 to 3 m wide).

Since 1999, the biological monitoring programme has been extended to include secondary and minor rivers, increasing the length of rivers biologically classified under the General Quality Assessment (GQA) to more than 5000 km.

The first available GQA chemical classifications of secondary rivers are for 2002 as the classification system requires three years' data. The primary rivers continue to be monitored chemically for GQA classification and as required by local, national and international legislation.

A list of the current river quality monitoring stations as well as a more detailed history of the development of river monitoring in NI can be found in A River Water Quality Monitoring Strategy for Northern Ireland(.PDF 823Kb).

Managing the Water Environment in Northern Ireland(.PDF 2.38Mb) details the findings of water and effluent quality monitoring in 2000.