A rapid bibliographical overview shows that the last decade has given rise to numerous scientific and technical works dealing on water quality (WQ) monitoring. During this period, many methods were developed, from complementary ones to standard procedures for improving WQ monitoring. Complementary approaches (online, in situ, remote) aim at giving more rapid and simple ways for WQ data acquisition. They can allow novel solutions to address temporal and spatial variations and lack of WQ data when monitoring is difficult to carry out in poor countries, for example. Finally, this chapter highlights the importance of considering optical characteristics of waters and soils and thus optical methods for WQ measurement.