Water is one of the essentials for life on Earth. Everyone has the right to access safe drinking water, but sadly, industrialization, poor waste management, and overpopulation are polluting water supplies. Thus, in order to ensure environmental sustainability, it is imperative to model and map surface water (SW) susceptible areas and their responses to runoff and spatiotemporal land use changes. The purpose of this investigation was to highlight the differences and similarities among the different tributaries of the Mahanadi River, Odisha, to determine the primary causes of pollution in the river basin, using Method based on the Removal Effects of Criteria (MEREC/M) and Measurement of Alternatives and Ranking according to Compromise Solution (MACROS) methodology. The study region was separated into 19 zones for ease of sample collection. A total of 21 water samples were collected during the 2020–2023 period and subjected to extensive physicochemical analysis. According to an analysis of the physicochemical data gathered, the water's TKN and EC were determined to be high when compared to WHO recommendations. The observation could be because there are a lot of possible anthropogenic sources in this watershed and it is primarily utilized for agricultural purposes. Additionally, the M-WQI value ranged from 34 to 381, suggesting excellent to unsuitable category. Around 57.89% of water locations (n = 11) exhibit poor-unsuitable class, thus illustrating overuse of inorganic fertilizers, contributes to pollution of water bodies. Also, it arises because of climatic changes along the agroecological zones. In order to meet increasing demand for clean water, sustainable use and conservation of available water resources, MACROS study was done to find out effects of agricultural nutrient pollution, along with different anthropogenic practices. As per its classification, Site Z-(9) represents the most polluted site, holding a highest score of Ui = 0.0469, followed by sites Z-(8), (19) and (2). The results demonstrate that WQ is affected by both point and non-point sources of pollution in rural and urban areas. Some of these sources includes use of fertilizers, sewage discharge, manures and pesticides, animal husbandry activities, inefficient irrigation practices, deforestation of woods, pollution due to industrial discharge, aquaculture, and agricultural runoff, domestic sewage, mining, and recreational activities. From the overall findings, it is concluded that samples from the upstream sites show better water quality (WQ) than downstream portions. The suggested contributions at the downstream side for WQ deterioration are industrial effluents from various industries such as nut-bolt industry, electroplating, and galvanizing and cycle industries residing in the nearby regions. Therefore, the implementation of MEREC and MACROS methodology in the present work, would offer a necessary step for proper management of the river channel, and it will be a very helpful tool for the public and decision makers to evaluate the WQ for sustainable management.