In this study, six rivers exposed to important agricultural and industrial discharges were selected in Samsun, the region of Mid-Black Sea region. During the wet (February) and dry (July) seasons of 2022, river water samples were taken and analyzes were made using 36 water quality parameters, 19 of which were PTE. In the evaluation of the quality of these surface waters, water quality index, heavy metal indices, human health evaluation indices and multivariate statistical analyzes were used. In some results, Fe (260.9–804.9 µg/L) and Al (392.9–1411.5 µg/L) metals exceeded the limit standard values, while other PTEs remained within the limit standard values. In addition, seasonal significant differences were found in TOC, TP, NO3–N, NH4–N, TSS, phenol, hardness and temperature parameters (p < 0.05). On the other hand, three main components were identified explaining 91.21% of the water quality change with PCA, indicating that the sources of pollution were anthropogenic. As for the WQI values, they were determined to be higher in the wet seasons (29.12–67.26) than in the dry seasons (9.47–31.66). The Kızılırmak River has been exposed to the most intense pollution among the six rivers. In this river, the WQI, HPI and HEI values in the rainy season were 67.26, 21.21 and 18.84, respectively. It was determined that Cd and Pb values did not have any side effects except for the As value in the river where CR is low in adults. However, it was found that the As value (1.3E-04) in the Kızılırmak River is higher than the CR predicted standard limit (> 1.0E-04).