In Indonesia, the Adiwiyata schools’ development program has implemented environmental education. These schools have a responsibility to preserve the environment, especially around school grounds. One of the elements of the Adiwiyata schools’ conservation program is the conservation of the Brantas watershed area which is currently experiencing degradation due to human activities. This study aimed to explain how environmental education in schools contributes to students’ knowledge, and to examine the efforts made by the Adiwiyata schools in the conservation of the Brantas watershed area. This research used quantitative and qualitative research methods. The quantitative method was carried out through a survey of 254 students at Adiwiyata schools through an online questionnaire. Qualitative data were collected through observations of school programs and policies as well as semi-structured interviews with teachers, students, and principals. The results of this study indicated that environmental education in Adiwiyata schools contributes to strengthening students’ cognitive and affective competencies towards the conservation of the Brantas watershed but not yet in the psychomotor domain. The Brantas watershed conservation efforts carried out by the Adiwiyata schools consist of monitoring river water quality, restoring riverbanks, and cleaning the river from pollutant waste. The realization of these efforts is the result of collaboration between the school and external parties, namely the Environment Agency, Jasa Tirta, the Tunas Hijau NGO, and the JKPKA Organization.
Keywords: environmental education, Adiwiyata, Brantas watershed, conservation, senior high school