This visualization based on data from the Surface Water and Ocean Topography (SWOT) satellite shows the average water level for lakes and reservoirs in the Ohio River Basin from July 2023 to November 2024.

Yellow indicates values greater than 1,600 feet (500 meters) above sea level, and dark purple represents water levels less than 330 feet (100 meters). Comparing how such levels change can help hydrologists measure water availability over time in a local area or across a watershed.

Since early 2023, SWOT has been measuring the height of nearly all water on Earth's surface – including oceans, lakes, reservoirs, and rivers – covering nearly the entire globe at least once every 21 days. The satellite also measures the horizontal extent of water in freshwater bodies. Earlier this year, the SWOT mission started making validated data (processed measurements that have been checked for accuracy) publicly available.

SWOT was jointly developed by NASA and the French space agency, CNES (Centre National d'Études Spatiales), with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. NASA's Jet Propulsion Laboratory, which is managed for the agency by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the KaRIn instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. CNES provided the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations. CSA provided the KaRIn high-power transmitter assembly. NASA provided the launch vehicle and the agency's Launch Services Program, based at Kennedy Space Center, managed the associated launch services.

To learn more about SWOT, visit: https://swot.jpl.nasa.gov/