The utilization and use of natural resources has significantly led to a decrease in the quality and quantity of the environment. This makes the utilization of natural resources must be performed wisely on the basis of the principles of sustainability (carrying capacity) in order that the natural resources owned by the regions can be utilized sustainably for current and future generations. It is hoped that understanding the carrying capacity of the environment becomes the first step for environmental management to realize the quality and quantity of a good environment. Ecosystem Services approach can be used to know the environmental support capacity in a region, including watersheds. Watersheds are often used as a basis for approaches when people want to solve various environmental damage issues, such as the problem of forest damage, erosion, landslides, floods, sedimentation, river water pollution and river shallowing. In Indonesia, there are hundreds of watersheds including Kayan and Sembakung watershed in North Kalimantan that serve as water supply areas and food supply areas. Therefore, this book aims to know the environmental support capacity of Kayan and Sembakung watershed in North Kalimantan Province in the provision of food and the provision of clean water. This book contains a description of the study of environmental support capacity of Kayan and Sembakung watershed in the provision of food and clean water; description of watershed concept, concept of environmental carrying capacity, concept of ecosystem services and concept of environmental carrying capacity based on ecosystem services; description of methods of determining the environmental support capacity of Kayan and Sembakung watershed based on ecosystem services, including the approach of study, scope of territory, materials and tools, data of studies and data analysis; description of the results of the study includes the environmental carrying capacity of Kayan and Sembakung watershed in the provision of food and clean water as well as the tendency of the supporting capacity of the clean water supply of Kayan and Sembakung watershed that becomes the basis for food supply; description of environmental issues, pressures, conditions/circumstances and the responses to Kayan and Sembakung watershed; and so forth. Therefore, this book is presented as one of the scientific reference sources that can be used as reference material for students and lecturers who study the sustainability of ecosystem-based environments.