KUALITAS MUTU PERAIRAN SUB DAERAH ALIRAN SUNGAI KALIGARANG DESA GOGIK DITINJAU DARI PARAMATER NITRAT, BOD, COD DAN DO

Garang River or often known as Kaligarang class I river is one of the sources of water that can be used to meet human water needs in the field of meeting the needs of clean water as raw water, agriculture and animal husbandry. The upstream Kaligarang River Basin (DAS) is one of the watersheds indicated in critical condition. One of the critical areas in the Kaligarang watershed is the sub-watershed from Kaligarang which crosses the village of Gogik to the village of Genuk, Ungaran Barat District, Semarang Regency. This study aims to determine the characteristics of the Kaligarang sub-watershed in the Gogik Village to Genuk Village in terms of the parameters of Nitrate, Biochemical Oxygen Demand (BOD), Chemical Oxogen Demand (COD) and Disolved Oxygen (DO). This research is a descriptive observational study with a cross sectional design. The sampling technique used was purposive sampling at 10 stations representing the sub-watershed of Gogik Village to Genuk Village as a whole. 500 mL of water samples were taken on the surface layer using a water sampler and stored in a coolbox for further analysis at the Regional Health Laboratory of Semarang Regency. Water sample analysis technique refers to SNI. The results showed that the nitrate value in the Kaligarang sub-watershed ranged from 10-100 mg/L, the BOD value varied between research stations, namely 0.4-57.4 mg/L, COD 40-1000 mg/L, DO 2.96- 4.98 mg/L. So that the quality of the water quality of the Kaligarang sub-watershed in Gogik village in terms of the Nitrate, BOD, COD parameters does not meet the requirements, while the DO parameter meets the requirements for class I river water quality PP RI No. 22 Year 2021.