What we monitor

The EPA implements the surface water hydrometric programme for each local authority. These hydrological programmes are vital in order to provide information for the assessment, development and management of water resources and the water-related environment in relation to such things as:

  • Providing data on the flowrates at times of water quality sampling
  • Dry weather flow  for proposed water abstractions for domestic and industrial use from rivers
  • Backward and forward routing for abstractions from lakes
  • Design of lake/channel control structures (weirs, flumes etc) for use in estimation of lake retention (turnover) time
  • 95 percentile flow  for the formulation of licence conditions for effluent discharge during low flow
  • Highest water level and related flowrate for use in bridge design and drainage works
  • Flood prevention and alleviation
  • Current water level and flow conditions for management of spillages and flood warning conditions
  • Continuous pattern of flow for management of reservoir storage, fisheries, landfills and nutrient management planning
  • Low flows and groundwater level information to assess groundwater resource
  • Linking of meteorological and hydrological forecasting

In order to make these evaluations, flow records covering a considerable length of time must be available. Of increasing importance in recent years is the use of hydrometric data to estimate nutrient loadings as part of catchment monitoring and management studies involving river, lake and estuarine systems.

In the wider European context, information on river flows has a supporting role in the Water Framework Directive. Likewise, long term information on river flows is required to assess any effects of climate change.

The EPA also makes use of the data collected by the OPW which has gauges at strategic locations on rivers and lakes in relation to arterial drainage, navigation and flood relief and the ESB which operates hydrometric stations to assist in hydroelectric power generation and water level control in relation to dam safety.