Water Quality Assessment and Pollution Status Using the STORET Method in the Welang, Gembong, and Rejoso Rivers, Pasuruan, East Java

 
High levels of anthropogenic activity along river basins are a major cause of declining water quality. The Welang, Gembong, and Rejoso are three large rivers in East Java, Indonesia, located in industrial and densely populated areas, and are currently experiencing pollution and water quality degradation. This study aimed to assess water quality and to determine the pollution status of these rivers. A descriptive survey method was employed from August to October 2024, and pollution levels were evaluated using the STORET method. The results showed that water quality parameters during the study period were as follows: temperature 28.1– 30.5°C, current velocity 0.10– 0.43m/ s, TSS 125– 137.5mg/ L, DO 4.88–5.98mg/ L, pH 7.05–7.35, nitrate 0.151– 0.215mg/ L, orthophosphate 0.115– 0.237mg/ L, COD 29.33– 53.15mg/ L, TOM 15.8– 25.8mg/ L, and Pb 0.46–1.44 mg/L. Several parameters—TSS, orthophosphate, COD, TOM, and Pb—exceeded the Class III water quality standards established in Government Regulation Number 22 of 2021. Based on the STORET method, pollution levels in the Welang, Gembong, and Rejoso Rivers were categorized as severe, with scores of –43, –43, and –35, respectively. Thus, the pollution status of all three rivers is classified as severely polluted. These findings highlight the urgent need for waste management strategies to reduce pollution from anthropogenic activities surrounding the Welang, Gembong, and Rejoso River Basins.