Nearshore bathymetry data from the Unalakleet River mouth, Alaska, 2019

This data release presents nearshore bathymetry data collected at the mouth of the Unalakleet River in Alaska, near the city of Unalakleet. The data were collected in August 2019 by the U.S. Geological Survey, Pacific Coastal and Marine Science Center. Nearshore bathymetry was measured along survey lines from the shore to a depth of approximately -7.4 m NAVD88 and in a portion of the estuary closest to the mouth. Bathymetry data were collected using small boat equipped with a single-beam sonar system and global navigation satellite system (GNSS) receiver. The sonar system consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9 degree beam. Depths from the seafloor to the echosounder were calculated using the digitized acoustic backscatter and sound velocity profiles, measured in multiple locations using a YSI CastAway CTD. The position of the boat and echosounder was recorded at 10 Hz using a Trimble R7 receiver and Zephyr 2 antenna. Survey-grade vertical and horizontal positions were achieved by applying differential corrections from a nearby GNSS base station installed for the purposes of this survey.