Technogenic Pollution of River Waters in the Atyrau Region: Hydrochemical Risk Assessment for Recreational Use

River waters in the Atyrau region are utilised intensively for both economic and recreational purposes. The distinctive natural-climatic conditions of the region and ongoing technogenic loading exert a direct influence on the spatial variability of water quality. Consequently, assessing the hydrochemical state of river waters—specifically identifying areas with high pollution risk—is a matter of critical importance. The purpose of this study is to assess the technogenic pollution of river waters in the Atyrau region through the analysis of hydrochemical risks associated with recreational water use. In 2025, surface water samples were collected from seven monitoring sites across the Atyrau region. The study determined pH, mineralisation (dry residue), basic ionic composition, total hardness, nitrogen compounds, permanganate oxidation, petroleum products, and heavy metals (Cu, Zn, Pb, Cr, and Cd). The data obtained served as the basis for comparing the hydrochemical characteristics of the river sections and evaluating the spatial variation in pollution levels. The results of the study indicated high levels of mineralisation and chloride concentrations in the Sagyz–Turgyzba–Zhana Tan sections. At the Atyrau–Damba sites, a relatively elevated content of lead (Pb) and chromium (Cr) was observed. Petroleum products were detected at all sites, with a maximum of 5.13 mg/L at the Zhana Tan site. Hazard Quotients (HQ) and Hazard Indices (HI) showed that metal-related risk was highest at the Atyrau and Damba sites (HI_metals = 3.57–4.02), whereas the total cumulative risk peaked at Zhana Tan owing to hydrocarbon loading. These disparities demonstrate that the hydrochemical state of river waters in the Atyrau region is non-uniform and varies depending on the location of the monitoring sites and the intensity of local technogenic factors. Monitoring data from 2025 provide scientific evidence of the spatial heterogeneity of both the hydrochemical state and the technogenic risks associated with recreational water use.