Analisis Status Mutu Air pada Parameter Fosfat (P₂O₅) dan Nitrat (NO₃) Menggunakan Metode STORET sebagai Upaya Pengelolaan Kualitas Air Danau Toba pada Desa Tongging Kabupaten Karo

Abstract

Lake Toba, as the largest lake in Indonesia, faces pollution challenges due to floating net cage (KJA) activities that contribute to an increase in phosphate (P₂O₅) and nitrate (NO₃) compounds. This study aims to evaluate the water quality status of Lake Toba in Tongging Village using the STORET method, determine the environmental carrying capacity based on phosphate and nitrate concentrations, and formulate appropriate management strategies using the SWOT method. The research was conducted by taking water samples at several points around KJA and lake inlet in Tongging Village, which were then analyzed for phosphate, nitrate, pH, temperature, dissolved oxygen (DO), and turbidity parameters. The results of the analysis show that the status of water quality at the research site is classified as moderately to severely polluted, with a STORET value that already exceeds the water quality limit in PP No. 22 of 2021. Concentrations of phosphate and nitrate that have exceeded the quality standards in the waters cause potential eutrophication, which is characterized by a decrease in dissolved oxygen levels and an increase in water turbidity. Recommended management strategies based on the calculation of the SWOT method include controlling the number of KJAs through limiting operational areas, using fish feed that is more environmentally friendly, and periodic monitoring of water quality parameters. In addition, increased public awareness and cross-sectoral cooperation are expected to encourage the sustainability of the Lake Toba ecosystem.