Wetlands are one of the most important elements of any urban area, acting like the kidneys of a city. Due to urban expansion and land use changes, wetlands are shrinking, and the quality of water is deteriorating at a faster rate. In this study, various water quality parameters—physical, chemical, and biological—were analyzed and compared with (BIS ISDWS, New Delhi 6:2–3, 2012) standards. Different statistical techniques and the Water Quality Index (WQI) were employed to assess the status and spatiotemporal patterns in the water quality of the Sagardighi Wetland, West Bengal. The data were collected from the Water Pollution Control Board, West Bengal, from 2012 to 2024. A total of 13 physicochemical parameters (pH, EC, Ca, Mg, Na, K, N, Cl, PO43, SO4, TDS, CaCO3, turbidity) and 4 microbial parameters (COD, BOD, DO and total coliform) were chosen for the study. The WQI was calculated using the weighted arithmetic water quality index method followed by Horton (J Water Pollut Control Fed 37:300–306, 1965) and developed by Brown et al. (Water Sew Works 117(10):339–343, 1970) and CODI, BODI, DO index were applied. In premonsoon time, WQI ranged from 63.19 (2010) to 17.77 (2024), whereas in the monsoon period, the WQI was 52.96 (2010) to 92.42 (2024), indicating poor water quality. The total coliform count was 7000 in 2024, indicating significant contamination, whereas COD was 28 mg/L and BOD was 7 mg/L, which are near the permissible limits. This study will enhance our knowledge about the spatiotemporal changes in urban water quality and provide future roadmaps that will be helpful for policymakers and concerned authorities in developing sustainable water quality management strategies.