The deterioration of the water environment in small towns in China due to urbanization has posed a significant challenge to their socioeconomic sustainability. Therefore, this study aims to employ an integrated assessment method based on the principal component analysis–minimal water quality index model (PCA–WQI_min) to objectively evaluate the water quality and analyze the pollution characteristics of Wangwenzhuang in Tianjin, thereby providing a scientific basis and decision-making support for the sustainable development of small towns. This study’s findings reveal that the PCA–WQI_min method identified four key water quality parameters essential for a comprehensive assessment of water quality across seasonal and spatial variations. The analysis revealed that the water quality in the investigated region remained at a “poor” level, with relatively consistent levels across the four catchments, ranked from poorest to best as the Xingchilong catchment area (29.61) < Jianxinpaigan catchment area (31.03) < Chilong catchment area (32.94) < Machangjian catchment area (39.61). This study revealed that the average WQI_min values slightly increased in the wet season relative to those in the dry season. This research highlights the critical importance of effectively managing domestic rural sewage and aquaculture pollution to increase surface water quality in small towns. Pollution prevention policies and multiple sources of pollution evaluation will be considered the focus of future studies.

The rapid expansion of mariculture in the Bohai Rim Region, a key marine economic zone in North China, has led to various environmental challenges. This study evaluated the spatiotemporal heterogeneity of emission fluxes and identified the primary influencing factors of mariculture in the Bohai Rim Region during 2014–2023. The findings hold both theoretical and practical significance for promoting the sustainable development of the nearshore environment. On the basis of mariculture data, the pollution coefficient method (PCM) was applied to quantify emission fluxes, whereas the logarithmic mean Divisia index (LMDI) model and Spearman rank correlation were used to analyze influencing factors. The results indicate that (1) the spatiotemporal heterogeneity of mariculture pollution discharge was influenced primarily by mariculture taxa and policy regulations and that (2) the filtration capabilities of shellfish suggest that an integrated mariculture strategy involving shellfish and other taxa could significantly mitigate pollution. The optimization of breeding structures and advancements in technology play crucial roles in reducing mariculture-related pollution emissions. (3) A significant decline in pollutant levels was observed following the implementation of the Action Plan for Comprehensive Management of the Bohai Sea (CMAP-BS). These findings provide a scientific basis for transforming the environmental management of mariculture in coastal regions of China.