This chapter explores spatial and temporal scaling and the impact of climate change on four basic water quality parameters: temperature, pH, dissolved oxygen, and suspended sediment. An introduction describing the conditions and changes in these water quality parameters is presented. Temporal scaling of water quality parameters is discussed on diel (24 h), precipitation event, and seasonal time scales. Discussion of longitudinal scaling of these parameters is included as well. Effects of climate change are presented here with a focus on observed trends, modeling results, and confounding factors in predicting climate change-induced shifts in water quality. This review highlights how factors such as geographic location, land cover, and human perturbations can alter water quality trends in rivers and streams.