<p>Dams are strategic tools for countries and their management of water resources. Within the Space for Climate Observatory (SCO) initiative and SWOT Downstream program, the StockWater project aims to put in place a system for monitoring water volume in dams. It is based on satellite data, and a specific processing system, thereby facilitating the work of the public authorities in this area.</p><p>Water resources monitoring, including surface and groundwater, is a vital issue for governments and public institutions. Water resources are essential for society and economic activity (drinking water, irrigation, hydroelectricity, industry, flood control) and for natural and water ecosystems.</p><p>Generally, reservoir stock information is collected and held by the local reservoir managers (public or private). Regional and national authorities might access this information with a certain latency, which depends on national water policies. Central authorities are then confronted with two issues: long latencies to retrieve water stock information and sparse or inexistent information about small reservoirs.</p><p>The project proposes a global solution to monitor reservoir stock volumes based on frequent satellite measurements. This solution is based on reservoir water extent monitoring by imaging satellites (Sentinel 1&2) based in the Surfwater processing chain, which integrates a multitemporal approach to improve water masks. Furthermore, StockWater innovation relies on reservoir estimation of Area/Elevation/Volume relationships just from a DEM, even when acquired after the reservoir construction.&#160;</p><p>Recent total volume estimations from DEM estimations have been qualified on hundreds reservoirs in France, ranging from 10 to 10000 hectares, providing errors lower than 20% on 77% of the reservoirs. About the general system assesment, Filling rates estimates yield an error lower than 8% on 75% of the measurements.</p><p>New versions are evaluated on Spain, France, India and Brazil and deployed on&#160; Burkina-Faso and Tunisia over more than 100 reservoirs. Results are available here: https://www.sco-stockwater.org/&#160; This system will also easily allow volume estimations from Elevation measurements (altimeters Jason, Sentinel3 with limited coverage or SWOT globally).</p><p>StockWater project, led by CNES and developed with CS-Group and SERTIT,&#160; holds a partnership initiative with CESBIO, GET, LISAH and FUNCEME/Universit&#233; Pernambuco laboratories and their local partners in Tunisia, Laos, Burkina-Faso, Brazil and India. StockWater is open to new countries willing to participate in future project expansions.</p>