To contribute to the efficiency of the water quality monitoring network of the hydrographical area of coastal Galicia (Northwest Spain), a sampling frequency that would ensure reliable verification of compliance with European Union standards, and a preliminary trend estimation of water
quality are calculated. The criterion applied was that for each of four quality determinants (flow rate, chemical oxygen demand, conductivity, and percent dissolved oxygen), the sampling frequency should ensure a 95% confidence interval for the annual mean whose upper limit would lie below
the corresponding legal threshold. During the study, all water tested complied with the more stringent standards for drinking water. The confidence interval and trend for flow rate were also calculated.
Water Environment Research® (WER®) publishes peer-reviewed research papers, research notes, state-of-the-art and critical reviews on original, fundamental and applied research in all scientific and technical areas related to water quality, pollution control, and management. An annual Literature Review provides a review of published books and articles on water quality topics from the previous year. Published as: Sewage Works Journal, 1928 - 1949; Sewage and Industrial Wastes, 1950 - 1959; Journal Water Pollution Control Federation, 1959 - Oct 1989; Research Journal Water Pollution Control Federation, Nov 1989 - 1991; Water Environment Research, 1992 - present.