In August 2020, the U.S. Geologic Survey acquired high-precision survey data of first-floor doorway threshold elevations at buildings in the Lake Champlain floodplain in Vermont. For a representative sample of buildings within the 106 feet (National Geodetic Vertical Datum of 1929) stage boundary of the regional flood-inundation map (Flynn and Hayes, 2019), 153 buildings, or nearly 12 percent of the total buildings, were surveyed. These data consist of Global Navigation Satellite System-derived orthometric heights in the North American Vertical Datum of 1988, which were measured by trigonometric leveling with a total station. Included in this data release are the raw and processed leveling control point data (unprocessed and processed GNSS benchmark and reference mark data, notes, and photographs), processed survey data for the first-floor elevations, scanned field notes, photographs from each field site, and a site map. Reference: Flynn, R.H., and Hayes, L., 2019, Flood-inundation maps for Lake Champlain in Vermont and New York: U.S. Geological Survey Scientific Investigations Report 2018–5169, 14 p., https://doi.org/10.3133/sir20185169. [Supersedes USGS Scientific Investigations Report 2016–5060.]