This paper discusses the use of an estuary monitoring toolkit "Nga Waihotanga Iho" as a central part of a Maori-centred education project undertaken by Kaipara hapu (sub-tribe), Te Uri O Hau, in Northland, New Zealand. The toolkit was designed by New Zealand's National Institute for Water and Atmospheric Research (NIWA). In this project, Te Uri O Hau collaborated with NIWA and regional high schools in order to use this toolkit as a mechanism for kaitikaitanga (environmental guardianship) and Indigenous-led environmental education. This paper demonstrates that approaches such as this can be powerful vehicles for Indigenous self-determination as Maori actively undertake tribal development and environmental guardianship, and strengthen the place of Indigenous knowledge, priorities and approaches within an evolving 'post-colonial' education system.