Hyperspectral measurements from prototypes of low-cost radiometers deployed across the Illinois, Delaware, Snake, and Sacramento-San Joaquin river basins from September 2023 through October 2025

In-situ hyperspectral radiometer deployments offer valuable ground truth data for atmospheric corrections of satellite remote sensing over inland and coastal water bodies. These measurements can also be used to model water-quality parameters directly from hyperspectral observations, making such instruments valuable additions to the U.S. Geological Survey (USGS) water-quality monitoring network. A major limitation to the expansion of in-situ hyperspectral radiometer deployments is the high cost of commercially available instruments. To address this, a prototype was built of a lower-cost unit assembled from commercial components. Three prototype units were deployed in the Illinois (Station ID: 5553700), Delaware (Station ID: 1467200), and Sacramento San-Joaquin (Station ID: 11455508) river basins from September 2023 to March 2024 to evaluate their suitability as a low-cost alternative. A unit was also deployed in the Snake River basin in Washington (Station ID: 13343590) from September 2025 to October 2025. Data collection supported the U.S. Geological Survey (USGS) Water Mission Area Next Generation Water Observing System (NGWOS) in coordination with the USGS California Water Science Center.