According to the Shivagrha inscription, a general public water project to alter the course of a river around Shivagrha temple was undertaken during the development on the temple. The river, recognized as being the Opak River, now runs north to south over the western side with the Prambanan temple compound. https://adelaidehindutemple.blogspot.com/2024/09/hanuman-mandir-south-australia-hindu.html