The Republic of Azerbaijan situated in the southeastern part of the South Caucasus faces acute water deficit. The water resources in this country are not only limited, but also occur highly unevenly. The greater part of water resources originates extraterritorially, i.e., beyond the borders of the state. The recent decades have witnessed the sharp growth of freshwater requirements associated, in particular, with the growing number of population and economic development. Apart from the water shortage, there is a problem of deterioration of the water quality, which results from poor wastewater management, inadequate monitoring of the water condition, and global climate warming. This chapter of the book studies the quality of the river waters in the Republic of Azerbaijan. The main sources of pollution of the freshwater resources are studied in detail with the focus on the analysis of the pressure of organic and inorganic substances on the quality of river water resources. In this context, the chapter also studies the effect of utility, industrial, and agricultural wastewaters on the quality of surface waters in the country.