Daily Coastal Groundwater Chloride Observations with Hydrogeological, Tidal, and Climatic Predictors — U.S. Atlantic and Gulf Coast (1906–2023)

This dataset compiles 243,753 daily groundwater chloride concentration observations from 46,289 monitoring wells across 13 U.S. Atlantic and Gulf Coast states (AL, DE, FL, GA, LA, MD, MS, NC, NJ, PA, SC, TX, VA), spanning 1906 to 2023. Each observation is enriched with a comprehensive set of static hydrogeological, dynamic tidal, and climatic predictors assembled from federal and state sources. The dataset was developed to support the research paper Predicting salinization of groundwater along the U.S. Atlantic and Gulf coasts with machine learning, as described in Tian et al. (2026, Water Resources Research). All observations were located within approximately 160 km (100 miles) of the coastline, as defined by the uploaded study area file.