This article takes issue with the uncritical way in which claims of ‘culture’, ‘tradition’ or ‘local knowledge’ are used in science and policymaking around the Balinese irrigators' association (subak). The growing problems of Balinese irrigated agriculture are increasingly framed in ‘cultural’ ways that are not neutral: such accounts of irrigated agriculture in relation to Balinese culture deeply influence the world of policymaking. In this article we discuss the emergence of Tri Hita Karana (THK; ‘the three causes of well-being’) as an ideology, scientific concept and policy concept in irrigated agriculture and the subak domain. We argue that this ideological concept is not simply ‘local wisdom’, ‘tradition’ or ‘culture’ but requires critical scientific scrutiny as part of wider processes of socio-political change. How is it mobilised? What does its growing popularity mean for our knowledge of Balinese irrigated agriculture, of policy processes directed at the subak and of the workings of policies in real-life contexts?