Water quality assessment to determine the trophic state and suitability of Lake Sentani (Indonesia) for various utilisation purposes

Abstract

Lake Sentani is one of the national priority lakes that must be saved from eutrophication and the threat of water quality degradation due to pollution. This study aims to assess the water quality parameters of Lake Sentani at ten study sites. We use two assessments to determine the trophic state, referring to Indonesia's criteria for lake trophic levels and the Trophic State Index (TSI). Also uses the Water Quality Index (WQI) to determine the suitability level of Lake Sentani water for various utilisation purposes. The study results show that the concentration of several parameters has exceeded the class-A to class-D quality standards. Lake Sentani tends to be eutrophic to hypereutrophic due to the high concentration of nutrient elements. Likewise, the TSI method classifies Lake Sentani into eutrophic to hypertrophic states (TSI_TP: 68.21–79.19). Lake Sentani's water transparency level includes eutrophic and mesotrophic (TSI_SD: 44.47–47.94) states. Based on the WQI value, the water quality of Lake Sentani is predominantly classified as poor to marginal as a source of drinking water (WQI: 44.56–54.10), so it is not suitable for use as a source of drinking water. Water quality is marginal if used to support recreational activities (WQI: 55.56–63.92). For use in aquaculture and irrigation, the water quality of Lake Sentani is classified as fair (WQI: 65.64–76.91) and good to excellent (WQI: 89.01–100.00), respectively. So, it is suitable for supporting aquaculture activities and as a water source for irrigation.