Bathymetric Data Collection for Larimore Dam in North Dakota, August 2020

Data were collected in August, 2020 to support development of a bathymetric map for Larimore Dam in Grand Forks County, North Dakota. Global Navigation Satellite System (GNSS) surveying equipment was used in static and real-time kinematic (RTK) mode to establish a local reference mark and check-in/check-out point, to collect water surface elevations, and to collect topographic points along established data collection transects. Topographic points were collected on land, in water too shallow for boating, and in areas of the lake where thick aquatic vegetation prohibited use of an echosounder and transducer. In areas of the lake deep enough for boating and where aquatic vegetation was not present, depth data was collected using an echosounder with a dual frequency (200/24 kilohertz with a 4/20 degree beam) transducer. Data were collected on a set of transects roughly perpendicular to the axis of the waterbody, plus on a set of oblique transects that intersected the regular transects. Data collected on the oblique transects is intended to be used in map accuracy and quality-assurance/quality-control measures. Bar checks were completed twice daily (before and after echosounder data were collected) on August 4 and August 7. GNSS RTK was used to navigate the survey vessel on data collection transects. This data release includes a polyline shapefile and metadata describing the data collection transects, a point shapefile and metadata describing the data collected with GNSS RTK, a point shapefile and metadata describing the edited data collected with echosounder and transducer, and a comma spaced variable file containing raw echosounder data with associated metadata.