Evolving together: transboundary water governance in the Colorado River Basin.

Transboundary collaboration between the United States (US) and Mexico in the Colorado River Basin has heightened in recent years, as climate change, population growth, and overallocation threaten the long-term stability of the region. Through a combination of document analysis and semi-structured interviews with key stakeholders, we examine patterns of change in the governance of the Colorado River, as the US and Mexico navigate socioeconomic, cultural, and political asymmetries to jointly share water over the past two decades. We ask: What key events and environmental agreements have influenced transboundary water governance in the Colorado River over the past 20 years? We draw on the rich scholarship on transboundary water governance, especially around international river basin organizations, to uncover patterns of engagement and collaboration over time. We focus on the binational scale with an eye to study governance at multiple scales including interactions and impacts at the national and subnational scales. Our findings illustrate how Mexico's role has evolved from a narrow one following a strict interpretation of the 1944 Treaty toward a more creative partnership between the US and Mexico demonstrated in binational negotiations and the creation of joint solutions to emerging challenges around water conservation and ecological restoration. We find transboundary water governance in the basin is influenced by both long-term and short-term contextual changes that can inform strategies key actors employ to bolster institutional resilience and take advantage of opportunities for transformative change. Further, we find that the evolution of the binational relationship is reflected in changes in the negotiation process and structure, which highlights the importance of trust and relationship building, transparency, joint fact-finding, and information sharing to foster collaboration. However, we also find uneven institutionalization of stakeholder participation and transparency in engagement patterns that may ultimately, serve to hinder governance and cooperation in the basin.