This data release contains results of a high-water mark survey across Upstate New York following flash flooding during July 9-10, 2023. The survey was conducted between July 12 and September 20, 2023 by U.S. Geological Survey (USGS) personnel, and is based on surveyed elevations of mud, debris, and seed lines (Koenig and others, 2016) left by the flooding. Real-time and static Global Navigation Satellite System (GNSS) surveying (Rydlund and Densmore, 2012), combined with differential leveling (Kenney, 2010), were used to determine high-water mark elevations at 186 locations. Additional data associated with the July 2023 flooding, such as photos of the survey locations, can be found in the USGS Flood Event Viewer, https://stn.wim.usgs.gov/fev/#2023JulyMANYVTFlood.