Freshwater Quality Analysis Based on RRA and Thailand River Protocol in Wonorejo River, Surabaya and Dlundung River, Mojokerto, East Java

Freshwater rivers are one of Indonesia’s most important water courses, traversing diverse landscapes from mountainous to coastal areas, and playing vital role in providing clean drinking water sources, and maintaining rich and diverse biodiversity across aquatic ecosystems. However, nowadays these rivers are increasingly threatened by various factors, such as increasing pollution, massive deforestation, and climate change, which have significant impacts on environmental sustainability and health. In this context, biomonitoring can be an effective tool to evaluate the health of aquatic ecosystems by utilizing the presence of living organisms in these waters as biological indicators. The method used in this study is to evaluate through scoring invertebrates found in freshwaters rivers. The evaluator determines the relevant parameters, classifies the categories of environmental conditions, defines the area to be evaluated, and assiggns a score to each parameter analyzed with the result being a Water Quality Index (WQI). This scoring result obtained from Dlundung showed score of 79, where 12 diverse animal types were found and resulted WQI of 6.5, which moderately clean category. Whereas, the Wonorejo showed score only 11 and 3 type of animals were found, and had WQI of 3.67, indicating the water in the river was classified as dirty.