Integrating blue-green water conservation and greywater reuse for sustainable water management in mountain ecosystems

Mountain ecosystems are facing unprecedented hydrological instability due to climate-driven glacial retreat and altered precipitation patterns. This article examines the concept of fragmented water management within a holistic Blue-Green-Grey water framework to promote environmental sustainability and support livelihoods. Research shows that green water, which includes soil moisture and evapotranspiration, often plays a dominant role in mountain hydrology but is less managed compared to blue water runoff. Therefore, ecological stewardship should focus on conserving forests and soil to stabilize green water and maintain blue water flow. Blue water management strategies are evolving from large-scale dams to decentralized, nature-based solutions, such as ancestral aquifer recharge and ice stupas. To achieve resource efficiency, a shift towards circularity is necessary by using treated greywater for agriculture and other nonpotable uses, which can help alleviate the increasing demand for blue water. While technical interventions are being implemented, they are insufficient without integrated governance.