Major international agreements governing the shared use of transboundary waters rarely deal explicitly with species conservation, yet they often have major implications for aquatic, avian, and terrestrial species. To meet conservation objectives, it may be necessary to find flexibility, or “adaptive capacity” within these agreements to enable conservation measures. This study applies incident analysis to assess the adaptive capacity of the Canada–US Columbia River Treaty (CRT) to respond to evolving species conservation needs. Like many other transboundary agreements, the terms of the CRT cover power production, flood protection and irrigation, but not species conservation. We analyze the discourses and normative expectations of politically relevant actors regarding an international conflict with Canada over the use of flow modifications by US agencies to conserve an endangered species of sturgeon. Four distinct discourse coalitions formed around the issue, each with its own interpretation of the problem, normative expectations about the rules that should apply, and power to shape decision making. The incident highlights how domestic conservation laws can directly impinge upon an international transboundary water treaty, and how flexibility can be found within existing institutional arrangements for conservation purposes. However, new norms for fish conservation were not fully incorporated into the CRT and decision-making authority for conservation-related disputes became more entrenched in the Treaty’s implementing agencies, potentially further excluding actors who might support fish conservation, such as environmental organizations and Indigenous governments. We recommend strategies to increase the adaptive capacity of the CRT and similar international agreements to enable species conservation.

管理跨界水域共享使用的主要国际协议很少明确涉及物种保护，但它们往往对水生、鸟类和陆地物种产生重大影响。为了实现保护目标，可能有必要在这些协议中找到灵活性或“适应能力”，以实施保护措施。本研究应用事件分析来评估加拿大-美国哥伦比亚河条约 (CRT) 对不断变化的物种保护需求的适应能力。与许多其他跨界协议一样，CRT 的条款涵盖电力生产、防洪和灌溉，但不包括物种保护。我们分析了政治相关行为者关于与加拿大就美国机构使用流量修改来保护濒临灭绝的鲟鱼物种的国际冲突的话语和规范期望。围绕这个问题形成了四个不同的话语联盟，每个联盟对问题都有自己的解释，对应该适用的规则的规范期望，以及影响决策的权力。该事件凸显了国内保护法如何直接影响国际跨界水条约，以及如何在现有的制度安排中为保护目的找到灵活性。然而，鱼类保护的新规范并未完全纳入 CRT，与保护相关的争端的决策权在条约的执行机构中变得更加根深蒂固，可能会进一步排除可能支持鱼类保护的行为者，例如环境组织和土著政府。我们建议增加 CRT 和类似国际协议的适应能力的策略，以实现物种保护。