Social movements are like ocean waves. They arise at a certain period of time, grow and become an effective agent of change for a while. Some succeed outright in their goals, some regain strength with fresh ideas and make another run at the shore, but many are carried out to sea by the irresistible tide of history. In the American West, the conservation response to natural resource depletion and crisis has followed this latter pattern. Since the late nineteenth-century, there have been four distinct waves of conservation. Each is now in a different stage of the ‘back-to-sea’ cycle, making way for an emerging fifth wave: agrarianism. This wave builds on the strengths and weaknesses of the previous waves as it meets the emerging conditions and challenges of the 21st century.