ABSTRAK

Sub DAS Nagara dimanfaatkan untuk wisata kerbau rawa, keramba jaring apung, permukiman, dan pasar yang berpotensi menurunkan kualitas air. Penelitian ini bertujuan menganalisis kualitas air, menentukan status mutu air menggunakan Indeks Pencemaran (IP) dan Indeks Kualitas Air (IKA), serta mengkaji tingkat kesuburan berdasarkan rasio N:P. Penelitian menggunakan metode survei pada tiga stasiun dengan teknik purposive sampling dan composite sampling. Parameter yang dianalisis meliputi suhu, kecerahan, TSS, pH, DO, BOD, nitrat, dan fosfat. Hasil menunjukkan bahwa suhu, kecerahan, TSS, pH, dan nitrat umumnya memenuhi baku mutu Kelas 2, sedangkan DO, BOD, dan fosfat pada beberapa stasiun melebihi baku mutu. Nilai IP berkisar 1,28-3,08 (tercemar ringan), IKA 63,33-66,67 (kategori sedang), dan rasio N:P (<10) menunjukkan kondisi eutrofik. Kualitas air Sub DAS Nagara telah mengalami penurunan sehingga diperlukan pengelolaan untuk menjaga keberlanjutan ekosistem.

Kata kunci: Kualitas Air, Indeks Pencemaran, Sub DAS Nagara.

ABSTRACT

The Nagara Sub-watershed supports swamp buffalo tourism, floating net cages, settlements, and traditional markets that may affect water quality. This study analyzed water quality, determined water status using the Pollution Index (PI) and Water Quality Index (WQI), and assessed trophic status based on the N:P ratio. A survey was conducted at three sampling stations using purposive and composite sampling. Parameters included temperature, transparency, TSS, pH, DO, BOD, nitrate, and phosphate. Results showed that temperature, transparency, TSS, pH, and nitrate generally met Class 2 water quality standards, whereas DO, BOD, and phosphate exceeded the standards at several stations. PI values ranged from 1.28-3.08 (lightly polluted), WQI values from 63.33-66.67 (moderate), and the N:P ratio (<10) indicated eutrophic conditions. These findings suggest that water quality has declined due to anthropogenic activities, highlighting the need for improved water resource management.

Keywords: Water Quality, Pollution Index, Nagara Sub Watershed