First Nations Elders are very concerned about whether enough clean drinking water will exist for future generations. Three highly respected Elders from the Southern Interior of British Columbia helped the author investigate First Nations water-based ecology: Mary Thomas from the Secwepemc (Shuswap), Millie Michell from the Nlaka'pamux (Thompson), and Mary Louie from the Syilx (Okanagan) Nation. This paper follows on from the author's previous examination of First Nations' spiritual and ecological perspectives on water (BC Journal of Ecosystems and Management 1(1):54-68). The Elders' vision of the relationships between water, land, and animals highlights an apparent shortcoming in Western science's definition of an ecosystem. In this paper, the author encourages a shift towards water-based ecosystem management, proposing to repair of the definition of forest ecosystems in a way that interweaves First Nations' philosophy with Western science's ecosystem-based management approach.