GQA Biological Sampling Frequency
From 1990 until 1998, just over 2,000 kilometres of rivers were biologically monitored annually on a three-season basis (spring, summer and autumn) at approximately 280 sites. Following a review of monitoring requirements, this was doubled so that over 5,000 kilometres of Northern Ireland's waterways are now being monitored. This extension increased the number of monitoring sites to almost 600.
In the Table of General Quality Assessment (GQA) biological classes(.PDF 162Kb)
the numbers in brackets beside the classes indicate the number of seasons during which stations were monitored in a particular year.
Reducing the number of seasons during which monitoring could result in rivers being wrongly classified, but this is outweighed by the additional information derived from the expanded monitoring network.
