Collaborative approaches to complex water quality problems can facilitate collective action across large watersheds with multiple, overlapping political jurisdictions, including Indigenous territories. Indigenous nations are increasingly engaging in collaborative water governance, in part, as a response to colonial legacies that have excluded Indigenous peoples from watershed management. This study uses social network analysis to explore emerging Klamath water governance networks. We seek to understand ongoing system transformation in contemporary water governance through tribal engagement in multi-jurisdictional water governance networks, from a system of Indigenous dispossession and exclusion (late 1800s-1980s) toward a yet unrealized system that centers Indigenous peoples. To envision the meaningful inclusion of Indigenous peoples in adaptive water governance, we first draw on criteria established by Indigenous water governance scholars. Then, we examine a snapshot of Indigenous participation in water quality governance in the Klamath Basin that focuses on the Karuk Tribe from 2018-2019. Specifically, Karuk tribal managers identified 21 different science-policy coalitions that they worked with on a range of water quality issues. We then used social network analysis methods to generate a network in which 210 different organizations were linked through co-membership in one or more coalitions. Our findings indicated that the Karuk and other Klamath Basin tribes play a central role in Klamath water quality governance and were not relegated to "stakeholder status." Using a community detection algorithm, we found that tribes were key players in the central technical working group that emerged through network connections. Applying a log-linear statistical model, we also observed a high level of mixing in the network across all types of organizations, including tribes. Finally, through a multi-membership model, we found that tribes were more strongly connected to influential network actors than NGOs, despite environmental NGOs being more numerous. These analyses demonstrate how tribal engagement can activate key mechanisms for water quality governance transformation, e.g., shifting information flows and changing system structures to more effectively center Indigenous nations. In addition to insights from social network analysis, we also highlight the limitations of technical water management in supporting the deep connections held between Indigenous peoples and their waters that are central to Indigenous water governance.