Spatiotemporal assessment of nutrient pollution and water quality in Lake Hashenge, Ethiopia

Abstract Freshwater quality is increasingly threatened by nutrient pollution, especially in closed-basin lakes like Lake Hashenge (LH), Ethiopia. This study explored how nutrient levels change across space and time between 2022 and 2025 and how they affect water quality, using the Drivers-Pressures-State-Impact-Response (DPSIR) framework. We collected 180 water samples from 15 sites during both wet and dry seasons and analyzed key physico-chemical and nutrient parameters using standard methods. Statistical tools—Principal Component Analysis (PCA) and Cluster Analysis (CA)—helped identify pollution sources and group sites by pollution status, while the Water Quality Index (WQI) and Comprehensive Pollution Index (CPI) provided an overall picture of ecological health. Results showed clear seasonal differences: nutrients tended to accumulate more during the dry season when dilution was limited. PCA pointed to nutrient-driven eutrophication, particularly at Debir, Endedo, and Abakiros, linked to human activities. Chlorophyll-a levels confirmed hypertrophic conditions throughout the year. CA revealed three pollution categories, highlighting spatial variability. While overall pollution was moderate, local hotspots stress the need for targeted watershed management, including land-use planning, buffer zones, and community awareness programs.