The document discusses the Columbia River basin and its history of dam construction and efforts to ensure fish passage. It provides: 1) A timeline showing the construction of mainstem dams on the Columbia River from 1930 to 2010. 2) An overview of the challenges to fish passage when dams were initially built and the various technical solutions and programs developed over time to improve downstream and upstream fish passage, based on scientific research. 3) Lessons learned from the Columbia River experience that could inform management of the Mekong River basin, where many dams are planned or under construction, including the need for long-term monitoring, measurable objectives, an ecosystem approach, political will, and flexibility.