Telah dilakukan penelitian untuk menganalisis kualitas air limbah yang berasal dari Pertambangan Emas Tanpa Izin (PETI) di Desa Bakan Kecamatan Lolayan Kabupaten Bolaang Mongondow. Parameter yang diukur adalah pH, padatan tersuspensi total (TSS), tembaga, kadmium, zink, timbal, arsen, nikel, kromium, merkuri, dan sianida. Pengambilan sampel dilakukan pada empat lokasi di sepanjang aliran air limbah buangan dari lokasi pertambangan emas. Nilai hasil pengukuran selanjutnya dibandingkan dengan Keputusan Menteri Negara Lingkungan Hidup No. 202 Thn. 2004 tentang Baku Mutu Air Limbah Bagi Kegiatan Penambangan Bijih Emas/Tembaga dan Keputusan Menteri Negara Lingkungan Hidup Republik Indonesia Nomor 5 Thn. 2014 tentang Baku Mutu Air Limbah. Hasil penelitian menunjukkan bahwa nilai pH di satu lokasi pengambilan sampel dan nilai TSS di dua lokasi pengambilan sampel berada di luar nilai baku mutu yang telah ditetapkan, sedangkan konsentrasi sianida dan semua logam yang dianalisis masih berada di bawah ambang batas yang ditetapkan.A research aimed to analyze quality of wastewater from Unlicensed Gold Mine in Bakan Village Lolayan District Bolaang Mongondow Regency has been conducted. Parameters examined were pH, total suspended solid (TSS), copper, cadmium, zinc, lead, arsenic, nickel, chromium, mercury, and cynide. Sampling was performed at four locations along the flow of wastewater sourced from unlicensed gold mine. The results were then compared to Decree of the Minister of State for the Environment No. 202 Yrs. 2004 on the Quality Standard of Waste Water from Gold/Copper Ore Mining Activities and Decree of the Minister of State for the Environment No. 5 Yrs. 2014 on the Quality Standard of Waste Water. The results showed that pH value at one location of sampling and TSS value at two locations of sampling were beyond the predefined quality standard, while the concentration of cyanide and all metals analyzed were below the prescribed threshold.