Kualitas air yang baik menjadi syarat utama sebagai pendukung berlangsungnya pemenuhan fungsi air untuk mendukung keperluan manusia sehari-hari. Pembuangan limbah peternakan baik limbah padat maupun limbah cair ke badan sungai atau tidak maksimalnya pengolahan limbah peternakan akan menurunkan kualitas air sungai baik secara fisika, maupun kimiawi karena limbah organic memicu oksidasi yang cukup tinggi. Keadaan demikian yang mengakibatkan kualitas air sungai di Desa Babadan, Kecamatan Pace Kabupaten Nganjuk menurun. Penelitian ini dilakukan untuk mengetahui perbedaan kualitas air sungai yang mengalir sebelum dan sesudah peternakan sapi di Desa Babadan, Kecamatan Pace, Kabupaten Nganjuk. Kualitas air di analisis berdasarkan beberapa parameter seperti Fisika dan Kimia. Pencemaran sungai ditandai dengan adanya nilai kulaitas air yang melebihi baku mutu air golongan II seperti COD, BOD, TSS, Amonia, pH, dan Suhu. Pengukuran kualitas air sungai dilakukan dengan observasi lapangan, pengambilan sampel pada enam titik air sungai pada saat musim penghujan, dan pengujian sampel di lapangan juga di laboratorium BARISTAND Surabaya. Hasil penelitian meunjukkan bahwa pada enam titik sampel yang diuji dan di bandingkan dengan baku mutu air golongan II yang di muat di PP No. 82 Tahun 2001 ditemukan bahwa tingkat pencemaran pada titik B1, C1, C2, dan C3 (aliran sungai setelah peternakan) secara umum lebih tinggi dibandingkan pada titik A1, dan A2 (aliran sungai sebelum peternakan). Tingginya pencemaran ditandai dengan kandungan COD, BOD, TSS, dan Amonia yang melebihi batas ambang baku mutu air golongan II.

Kata kunci: Kualitas Air, Pencemaran air, Limbah Organik

Good water quality becomes the main requirement as a supporter of the fulfillment of water function to support daily human needs. Farm waste disposal, either solid waste or liquid waste to the river body or the anoptimal waste treatment of farms will decrease the quality of the river water either in physics, as well as chemically because organic waste caused a high oxidation. This situation has caused river water quality in Babadan Village, Pace District, Nganjuk Regency declined. This research is conducted to investigate the difference quality of the river water that flowing before and after the cow farm in Babadan village, Pace District, Nganjuk Regency. The analysis quality of water is based on several parameters such as physics and chemistry. River pollution is characterized by the value of the quality of water that exceeds the standards of second class water such as COD, BOD, TSS, Ammonia, pH, and Temperature. Data were collected using field observation, water sampling at six point of river flow during rainy sesason, and testing water sample at BARISTAND laboratory Surabaya. The result of the research show that at six sample points that tested and and compared with the quality of water grade II in PP No. 82/2001 was found that the pollution level at B1, C1, C2, and C3 (river flow after the farm) in general is Higher than A1, A2 (the river flow before the farm). The high pollution is characterized by the content of COD, BOD, TSS, and ammonia, which exceeds the threshold of water quality of II class.

Keywords: Water Quality, Water Pollution, Organic Waste