Bathymetric data for Whiskeytown Lake, December 2018

The Swath bathymetric survey was conducted with a SWATHplus-M 234-kHz interferometric side-scan sonar system pole-mounted on the U.S. Geological Survey (USGS) R/V San Lorenzo. During the mapping mission, an Applanix POS-MV (Position and Orientation System for Marine Vessels) was used to position the vessel during data collection, and it also accounted for vessel motion such as heave, pitch, and roll. The POS-MV also recorded position and vessel motion parameters for later post-processing. Sound-velocity profiles were collected throughout the survey days with a Castaway sound velocimeter. Post-processed POS-MV Smoothed Best Estimate of Trajectory (SBET) files were merged with the survey line files using BathySwath software and then the line files were imported into Caris HIPS and SIPS software. Soundings were cleaned for obvious errors and gridded into a 2-m base surface. The base surface was exported as an XYZ ascii file in UTM-10 coordinates referenced to the WGS84 ellipsoid. The ascii file was transformed to UTM-10, NAD83(2011) coordinates relative NAVD88 using VDatum software (version 3.7).

Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.

The Swath bathymetry data were gridded into a 1-m resolution raster, then exported to a TIFF file following the same steps as with the 2-m resolution data (above) and added to the data release. The Entity and Attribute Overview section of the metadata was revised accordingly. Additional survey data for 2020 was added to the overall data release, so minor edits were made to the Purpose section of the metadata to refer to the new data.