Author(s): Tri Soeprobowati
Email (s): firstname.lastname@example.org
Institution or organization of origin: Diponegoro University
Telaga Balekambang e is located next to Arjuna temple, Dieng Plateau, Central Java. Historically, Balekambang was an ancient lake with the function of a reservoir to protect flooding in the Arjuna temple. Telaga is a local name for small lakes. Balekambang is one of the critical lakes in Dieng, its size is reduced sharply due to sedimentation and pumping water for irrigation. In the dry season, this lake is dried, some parts of Balekambang Lake had high sedimentation and converted for agricultural farmland. The purpose of this research is to determine the recent condition of Balekambang Lake, inferring its water quality using the diatom index. Diatoms are microalgae that inhabit a wide variety of aquatic habitats, their high natural abundance, and diversity in lentic ecosystems and their capability to be preserved in the sediment due to their siliceous cell wall. The upper sediment was collected from 4 sites, digested with 10% HCl and H2O2 to remove organic materials. The residue was mounted using Naphrax and the diatom valves were identified under a microscope with 1,000 magnification. The water quality status of each layer was investigated using 18 diatom indices, performed using Omnidia software version 6.0. Sixty-seven diatom species were identified. The dominance of pollution-tolerant species, such as Navicula and Nitzschia was association with the formation of depositary habitats.