The general trend in water quality management has been to gather and use information on water quality variables for purposes of planning, design, and operation of water resources systems and wastewater treatment. However, the growing concern for environmental quality has given rise to a new trend in respect of the impact of water quality variables on human health and life conditions. Thus, there is the need for better understanding of how water quality processes evolve both in time and space under natural and man-made conditions. This accentuates the need for more efficient practices of monitoring to satisfy the objectives of water quality management plans. Upon this need, the adequacy of collected water quality data and the performance of existing monitoring networks have been seriously evaluated within the last decade. Problems observed in available data and shortcomings of current networks have led researchers to focus more critically on design procedures used. This paper examines the state-of-the-art in design of water quality monitoring networks. Available design procedures are discussed with respect to three basic features of a network: selection of sampling sites, sampling frequencies, and variables to be sampled. In conclusion, recommendations are presented for improvement of current approaches to the design problem.
