A study of woodland ecosystems that provide habitat for rare, endangered species along streams, rivers throughout California reveals some ecologically important areas are inadvertently benefiting from water 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.