Salinity data synthesized and summarized from both EPA and USGS publicly available data. This dataset is associated with the following publication: Kaushal, S., S. Shelton, P. Mayer, B. Kellmayer, R. Utz, J. Reimer, J. Baljunas, S. Bhide, A. Mon, B. Rodriguez-Cardona, S. Grant, T. Newcomer Johnson, J. Malin, R. Shatkay, D. Collison, K. Papageorgiou, J. Escobar, M. Rippy, G. Likens, R. Najjar, A. Mejia, A. Lassiter, M. Li, and R. Chant. Freshwater Faces a Warmer and Saltier Future from Headwaters to Coasts: Climate Risks, Saltwater Intrusion, and Biogeochemical Chain Reactions. BIOGEOCHEMISTRY. Springer, New York, NY, USA, 168: 31, (2025).