Purpose: analysis of problematic issues associated with the hydrochemistry of natural waters and the processes occurring in the irrigation systems of Rostov region. Discussion. The specificity of growing crops associated with irrigated agriculture has led to the formation of significant volumes of drainage and waste water (58676.5 thousand cub. m at the level of 2019). The quality of drainage wastewaters is determined by the hydrochemistry of groundwater and water intakes and has a seasonal character. In drainage systems operation of the Central irrigated zone, an unregulated inflow of salt-forming ions into water inlets was noted, and their concentration in the places where drainage wastes are discharged into small water bodies of the Lower Don (for example, Kostylevsky pr., Kolodezki ur., Solenaya river, erik Besheny) differs little from the background geochemical concentrations and corresponds to the natural saline background of the studied objects. Since irrigation and drainage systems are the objects of negative impact on the environment, uncontrolled natural processes of salt-forming ions migration in adjacent environments in combination with desalinization processes during the irrigation period led to violations of ecological legislation by the land reclamation and agricultural water supply departments in terms of exceeding the standards of maximum permissible concentrations for water bodies for fishery purposes, approved by the Order of the Ministry of Agriculture of 13.12.2016 no. 552. Conclusions. Regularities in formation of salt-forming ions migration processes in adjacent media have been revealed. It has been determined that one of the sources and agents of “saline contamination” of drainage and natural waters is groundwater. Hydrochemical materials and analysis of regulatory legal acts in terms of water bodies protection and use indicate the need to establish standards admitted to chemical substances concentrations disposal, taking into account the regional natural (nominally natural) hydrochemical background and natural and climatic characteristics differentiated for each small water body.
