<![CDATA[ABSTRAK Pencemaran laut akibat aktivitas antropogenik di wilayah pesisir menjadi permasalahan lingkungan yang serius karena dapat mengganggu keseimbangan ekosistem dan kesehatan masyarakat. Penelitian ini bertujuan menganalisis kualitas dan status mutu air laut di Perairan Pangkalan Susu, Kabupaten Langkat menggunakan metode Indeks Pencemaran (IP) dan STORET. Sebanyak 32 sampel air diambil dari empat lokasi (Perairan Penyelam, Dok, Dermaga C, dan SBM). Parameter yang dianalisis meliputi fisika (kecerahan, TDS, TSS, suhu, kekeruhan), kimia (pH, salinitas, amonia, DO, BOD, COD, nitrat, nitrit, fosfat), dan biologi (total coliform, fecal coliform). Analisis data mengacu pada Keputusan Menteri Negara Lingkungan Hidup Nomor 115 Tahun 2003 dan dibandingkan dengan baku mutu air laut untuk biota laut sesuai dengan PP RI No. 22 Tahun 2021. Hasil penelitian menunjukkan bahwa parameter TDS (10,190-20,592 mg/L), Nitrat (0.96-1.44 mg/L), dan Fosfat (0.16-0.26 mg/L) telah melampaui baku mutu PP RI No. 22 Tahun 2021 di seluruh lokasi, sementara parameter lain seperti pH, DO, BOD, COD, dan Total Coliform masih berada dalam batas aman. Berdasarkan metode STORET, seluruh lokasi tergolong Tercemar Sedang dengan skor -15 hingga -20. Berdasarkan metode Indeks Pencemaran, seluruh lokasi tergolong Cemar Ringan dengan nilai IP 3.70-4.26. Upaya pengelolaan yang direkomendasikan meliputi pengendalian masukan nutrien dari limbah domestik dan pertanian, pengawasan aktivitas pelabuhan, serta pemantauan kualitas air secara berkala. Kata kunci: indeks pencemaran, kualitas air laut, langkat, pangkalan susu, STORET ABSTRACT Marine pollution due to anthropogenic activities in coastal areas is a serious environmental problem as it can disrupt ecosystem balance and public health. This study aims to analyze the quality and status of seawater in Pangkalan Susu Waters, Langkat Regency using the Pollution Index (PI) and STORET methods. A total of 32 water samples were collected from four locations (Penyelam, Dock, Pier C, and SBM Waters). Parameters analyzed included physical (brightness, TDS, TSS, temperature, turbidity), chemical (pH, salinity, ammonia, DO, BOD, COD, nitrate, nitrite, phosphate), and biological (total coliform, fecal coliform). Data analysis referred to the Decree of the State Minister of Environment Number 115 of 2003 and compared with seawater quality standards for marine biota according to Government Regulation Number 22 of 2021. The results showed that TDS (10,190-20,592 mg/L), nitrate (0.96-1.44 mg/L), and phosphate (0.16-0.26 mg/L) exceeded the quality standards of Government Regulation Number 22 of 2021 at all locations, while other parameters such as pH, DO, BOD, COD, and total coliform remained within safe limits. Based on the STORET method, all locations were classified as Moderately Polluted with scores ranging from -15 to -20. Based on the Pollution Index method, all locations were classified as Lightly Polluted with PI values ranging from 3.70 to 4.26. Recommended management efforts include controlling nutrient inputs from domestic and agricultural sources, monitoring port activities, and conducting regular water quality monitoring. Keywords: langkat, pangkalan susu, pollution index, seawater quality, STORET]]>
