Lakes around the world are heavily impacted by climate change. Droughts, floods, higher water temperatures, changes in biodiversity, even sea level rise, all have an impact on fresh water lakes. This article addresses the question what legal measures are needed to protect lakes against these impacts, with a focus on biodiversity conservation. How can law help to implement the necessary climate change adaptation measures related to biodiversity conservation for lakes? Throughout the world, lakes are facing deterioration due to intensive economic use. Climate change is exacerbating this situation. The only way forward is through implementing massive ecosystem restoration and connectivity policies, adjusted water management, and policies aimed at assisted colonization of endangered species. Current international and EU law do not explicitly require such policies to be developed and implemented, at least not in a legally binding way. Restoration measures, taking into account current and future climate change impacts, are required in order to achieve the overarching goals of nature conservation and climate change instruments (biodiversity conservation and climate change adaptation). The case of Lake IJssel in the Netherlands shows that a long-term concerted effort is needed with sufficient budget in place, to achieve the necessary changes. The article details how law can help to implement the necessary climate change adaptation measures for lakes.