A study of woodland ecosystems that provide habitat for rare and endangered species along streams and rivers throughout California reveals that some of these ecologically important areas are inadvertently benefitting from water that humans are diverting for their own needs. Though it seems a short-term boon to these ecosystems, the artificial supply creates an unintended dependence on its bounty, threatens the long-term survival of natural communities and spotlights the need for changes in the way water is managed across the state.