Pengaruh Aktivitas Masyarakat terhadap Kualitas Perairan Waduk Sermo Kabupaten Kulon Progo

JOHLIN S. FUDIKOA, Dr. Slamet Suprayogi, M. S.; Prof. Dr. Suwarno Hadisusanto, M. S.

2021 | Tesis | MAGISTER ILMU LINGKUNGAN

Waduk Sermo terletak di Desa Hargowilis dimanfaatkan sebagai penyedia air baku PDAM dan air irigasi, serta sarana pariwisata. Pemanfaatan waduk dalam berbagai aktivitas masyarakat dapat menurunkan kualitas air waduk. Aktivitas masyarakat di sepanjang Daerah Aliran Sungai yang menuju waduk, di sekitar waduk, maupun di badan waduk dapat menjadi sumber pencemar waduk itu sendiri. Penelitian ini bertujuan untuk (1) menganalisis kualitas air dan menentukan tingkat pencemaran Waduk Sermo, (2) menganalisis komunitas fitoplankton berdasarkan tingkat pencemaran Waduk Sermo, dan (3) menganalisis pengaruh aktivitas masyarakat terhadap Status Mutu Air Waduk Sermo. Penelitian dilakukan dengan mengambil sampel air waduk pada 8 titik yang dibagi berdasarkan aktivitas masyarakat. Analisis kualitas air terdiri atas parameter fisik dan kimia air, sedangkan tingkat pencemaran air dianalisis dengan metode Indeks Pencemaran. Parameter yang diuji terdiri atas suhu, warna, bau, kecerahan, TSS, pH, DO, BOD, COD, amoniak, nitrit, nitrat, dan fosfat. Analisis komunitas fitoplankton menggunakan indeks diversitas, dominansi, dan kemerataan. Analisis aktivitas masyarakat dilakukan dengan wawancara untuk mengetahui bentuk pemanfaatan air waduk. Hasil penelitian menunjukkan bahwa (1) kualitas air Waduk Sermo mengalami penurunan, ditandai dengan parameter TSS, BOD, COD, fosfat, dan nitrat yang tidak memenuhi standar baku mutu air Provinsi Daerah Istimewa Yogyakarta kelas I dan II. Perairan Waduk Sermo tergolong cemar ringan dalam peruntukannya sebagai air baku PDAM dengan nilai Indeks Pencemaran yang berkisar antara 1,007-3,153. Peruntukan Waduk Sermo sebagai penyedia air irigasi, sarana pariwisata, perkebunan, dan peternakan tergolong tidak tercemar dan cemar ringan dengan nilai Indeks Pencemaran yang berkisar antara 0,733-2,993, (2) fitoplankton Waduk Sermo tersusun atas 5 kelas dengan total 49 marga yang ditemukan, dengan kelimpahan fitoplankton berkisar antara 1.075-66.000 ind/l. Diversitas fitoplankton tergolong rendah dan sedang, tidak ada dominansi marga, dan keseragaman marga relatif merata, (3) limbah aktivitas masyarakat yang berasal dari sungai dan sekitar waduk berperan sebagai sumber pencemar sehingga Status Mutu Air Waduk Sermo tergolong cemar ringan. Limbah aktivitas rumah tangga, pertanian, peternakan, dan industri kecil yang berada di sepanjang sungai Gelo, Ngrancah, Bengkok, dan Lurung cenderung dominan menyumbangkan bahan pencemar dibandingkan limbah aktivitas masyarakat di sekitar waduk.

Sermo Reservoir, located in Hargowilis Village, is used as a provider of PDAM raw water and irrigation water, as well as tourism facilities. Utilization of reservoirs in various community activities can reduce the quality of reservoir water. Community activities along the watershed leading to the reservoir, around the reservoir, as well as in the reservoir body can be a source of pollution for the reservoir itself. This study aims to (1) analyze water quality and determine the level of pollution of the Sermo Reservoir, (2) analyze the phytoplankton community based on the level of pollution of the Sermo Reservoir, and (3) analyze the effect of community activities on the Water Quality Status of the Sermo Reservoir. The research was conducted by taking reservoir water samples at 8 points which were divided based on community activities. Analysis of water quality consists of physical and chemical parameters of water, while the level of water pollution is analyzed by the Pollution Index method. The parameters tested consist of temperature, color, odor, brightness, TSS, pH, DO, BOD, COD, ammonia, nitrite, nitrate, and phosphate. Phytoplankton community analysis used diversity, dominance, and evenness indices. Analysis of community activities was carried out by interviewing to determine the form of reservoir water utilization. The results showed that (1) the water quality of the Sermo Reservoir had decreased, indicated by the parameters of TSS, BOD, COD, phosphate, and nitrate, which did not meet the water quality standards of the Yogyakarta Special Region Province's classes I and II. The waters of the Sermo Reservoir are classified as lightly polluted in their designation as PDAM raw water with a Pollution Index value ranging from 1.007 to 3.153. The designation of the Sermo Reservoir as a provider of irrigation water, tourism facilities, plantations, and livestock is classified as unpolluted and lightly polluted with a Pollution Index value ranging from 0.733-2,993, (2) The phytoplankton of the Sermo Reservoir is composed of 5 classes with a total of 49 genera found, with the abundance of phytoplankton ranging from 1,075-66,000 ind/l. Phytoplankton diversity is classified as low and moderate, there is no clan dominance, and genera uniformity is relatively even, (3) community activity waste originating from rivers and around the reservoir acts as a pollutant source so that the Sermo Reservoir Water Quality Status is classified as lightly polluted. Waste from household activities, agriculture, animal husbandry, and small industries along the Gelo, Ngrancah, Bengkok, and Lurung rivers tends to be dominant in contributing pollutants compared to the waste from community activities around the reservoir.

Kata Kunci : Aktivitas Masyarakat, Fitoplankton, Kualitas Air, Tingkat Pencemaran, Waduk Sermo. / Community Activities, Phytoplankton, Pollution Level, Sermo Reservoir, Water Quality