EVALUASI PELAKSANAAN KEGIATAN USAHA MINYAK DAN GAS DALAM MENJAGA KUALITAS PERAIRAN DI KABUPATEN GRESIK

Abstract

Kegiatan usaha minyak dan gas di Lapangan Ujungpangkah, Kabupaten Gresik, menghasilkan air terproduksi dan limbah cair yang berpotensi memberikan tekanan terhadap lingkungan perairan pesisir. Perairan tersebut juga dipengaruhi oleh masukan sungai, limpasan daratan, pasang surut, pengadukan sedimen, serta berbagai aktivitas antropogenik. Penelitian ini bertujuan menganalisis status kualitas lingkungan perairan selama periode 2020–2025, menentukan lokasi prioritas berdasarkan tingkat pencemaran dan sensitivitas perairan, serta merumuskan strategi intervensi untuk meningkatkan efektivitas pengelolaan lingkungan dalam pelaksanaan kegiatan usaha minyak dan gas. Penelitian menggunakan data primer dan sekunder yang mencakup hasil pemantauan kualitas air dan ekosistem pada 21 titik pengamatan. Parameter kualitas air terdiri atas parameter fisika, kimia, logam berat, dan mikrobiologi, sedangkan kondisi ekosistem dianalisis berdasarkan plankton, bentos, dan ikan. Data dianalisis secara temporal dan spasial serta dibandingkan dengan baku mutu sesuai peruntukan perairan. Status kualitas perairan ditentukan menggunakan Indeks Kualitas Air Laut (IKAL) berbasis National Sanitation Foundation–Water Quality Index (NSF-WQI) dan Indeks Pencemaran (IP). Analisis sensitivitas operasional menggunakan koefisien variasi untuk mengidentifikasi parameter dan lokasi dengan keragaman kondisi tertinggi. Hasil analisis kualitas air, kondisi ekosistem, pengelolaan perusahaan, serta masukan pemangku kepentingan selanjutnya diintegrasikan menggunakan analisis SOAR (Strengths, Opportunities, Aspirations, and Results). Hasil penelitian menunjukkan bahwa kualitas lingkungan perairan Kabupaten Gresik secara umum tergolong baik, tetapi tidak seragam antarlokasi dan antarperiode. Nilai IKAL berkisar antara 53,75–89,68 dengan rata-rata 80,92 yang termasuk kategori baik. Dari 219 hasil perhitungan IP, sebanyak 34,2% memenuhi baku mutu, 50,7% tergolong tercemar ringan, 4,1% tercemar sedang, dan 11,0% tercemar berat. Tekanan tertinggi ditemukan di TP-1 dan TP-2 pada Semester 2 tahun 2025. Nilai IP pada kedua lokasi masing-masing mencapai 16,38 dan 14,30 atau tergolong tercemar berat, sedangkan nilai IKAL masing-masing sebesar 53,75 dan 59,17 atau berkategori sedang. Kondisi tersebut terutama dipengaruhi oleh tingginya kekeruhan, TSS, nitrat, dan fosfat. MP-6, Outfall Line OB, dan Jetty Maspion menjadi lokasi prioritas berikutnya karena menunjukkan tekanan pada periode tertentu. Sebagian besar parameter logam terlarut dan mikrobiologi masih memenuhi baku mutu, sedangkan keberadaan plankton, bentos, dan ikan menunjukkan bahwa fungsi biologis perairan masih berlangsung. Meskipun demikian, perubahan struktur komunitas biota dan kandungan logam dalam jaringan ikan tetap memerlukan pemantauan. Tekanan kualitas perairan cenderung bersifat lokal dan belum dapat dikaitkan secara langsung dengan satu sumber pencemar karena dipengaruhi oleh interaksi masukan sungai, limpasan daratan, pengadukan sedimen, pasang surut, dan kemungkinan kegiatan operasional. Berdasarkan analisis SOAR, strategi yang direkomendasikan adalah pengelolaan lingkungan adaptif berbasis lokasi prioritas, integrasi data, dan hasil terukur. Strategi tersebut meliputi peningkatan frekuensi pemantauan di TP-1 dan TP-2, pengambilan sampel secara bersamaan pada titik pembuangan, perairan penerima, dan lokasi pembanding, evaluasi berkala fasilitas pengolahan air terproduksi dan limbah cair, pemantauan terpadu kualitas air dan biota, serta penguatan penanganan keluhan masyarakat. Keberhasilan pengelolaan diarahkan pada pencapaian IKAL sekurang-kurangnya 80, penurunan IP di lokasi prioritas hingga paling tinggi 5 sebagai target perbaikan awal, pencegahan peningkatan ekstrem TSS dan nutrien, kestabilan kondisi biota, serta pelaporan kinerja lingkungan setiap semester.

Oil and gas operations at the Ujungpangkah Field in Gresik Regency generate produced water and liquid effluents that may exert pressure on the surrounding coastal environment. These waters are also influenced by riverine inputs, land runoff, tidal dynamics, sediment resuspension, and various anthropogenic activities. This study aimed to analyze the environmental quality of the waters from 2020 to 2025, identify priority locations based on pollution levels and environmental sensitivity, and formulate intervention strategies to improve the effectiveness of environmental management associated with oil and gas operations. The study employed primary and secondary data, including water quality and ecosystem monitoring results from 21 sampling stations. Water quality assessment covered physical, chemical, dissolved heavy metal, and microbiological parameters, while ecosystem conditions were evaluated using plankton, benthos, and fish data. The data were analyzed spatially and temporally and compared with applicable water quality standards according to the designated use of each monitoring location. Water quality status was assessed using the Marine Water Quality Index (MWQI), adapted from the National Sanitation Foundation Water Quality Index (NSF-WQI), and the Pollution Index (PI). An operational sensitivity analysis based on the coefficient of variation was conducted to identify parameters and locations exhibiting the greatest variability. The results of the water quality, ecosystem, environmental management, and stakeholder assessments were subsequently integrated using the SOAR framework, comprising Strengths, Opportunities, Aspirations, and Results. The results indicated that the overall environmental quality of the waters in Gresik Regency was generally classified as good, although substantial variations occurred among locations and monitoring periods. MWQI values ranged from 53.75 to 89.68, with an average of 80.92, corresponding to the good category. Of the 219 PI assessments, 34.2% met the applicable water quality standards, 50.7% were classified as slightly polluted, 4.1% as moderately polluted, and 11.0% as heavily polluted. The highest environmental pressures were recorded at TP-1 and TP-2 during the second semester of 2025. The PI values at these stations reached 16.38 and 14.30, respectively, placing both stations in the heavily polluted category. Meanwhile, their MWQI values were 53.75 and 59.17, respectively, corresponding to the moderate category. These conditions were primarily associated with elevated turbidity, total suspended solids, nitrate, and phosphate. MP-6, the Observation Basin outfall, and Jetty Maspion were identified as secondary priority locations because they experienced environmental pressures during certain monitoring periods. Most dissolved heavy metal and microbiological parameters remained within the applicable water quality standards. The continued presence of plankton, benthos, and fish indicated that the basic biological functions of the aquatic ecosystem were still maintained. Nevertheless, changes in community structure and the presence of metals in fish tissues require continued monitoring. The identified water quality pressures tended to be localized and could not be conclusively attributed to a single pollution source because they may have resulted from interacting influences, including riverine inputs, land runoff, sediment resuspension, tidal processes, and potential operational activities. Based on the SOAR analysis, the recommended strategy is adaptive environmental management that prioritizes critical locations, integrates multiple data sources, and applies measurable performance indicators. The proposed interventions include increasing the monitoring frequency at TP-1 and TP-2; conducting simultaneous sampling at discharge points, receiving waters, and reference stations; periodically evaluating produced-water and wastewater treatment facilities; integrating water quality and biological monitoring; and strengthening the management of community complaints. Environmental management targets include maintaining an MWQI of at least 80, reducing PI values at priority locations to no more than 5 as an initial improvement target, preventing extreme increases in suspended solids and nutrients, maintaining stable biological conditions, and reporting environmental performance every semester.