Analysis of water fertility status based on the Trophic State Index (TSI) in the Air Hitam Urban Polder, Samarinda Ulu District, East Kalimantan. jipt [Internet]. 2025 Oct. 29 [cited 2025 Dec. 3];4(2):119-27. Available from: https://e-journals2.unmul.ac.id/index.php/jipt/article/view/2437