Bathymetric Survey of Upper Lake Mary near Flagstaff, Arizona in 2024 - Digital Elevation Model

The City of Flagstaff in northern Arizona utilizes Upper Lake Mary reservoir for approximately 25 to 30 percent of its water supply and understanding the detailed topography of the storage basin is essential for effective water management. The U.S. Geological Survey incorporated modern bathymetric and ground survey techniques to construct a 1-meter (1m) resolution digital elevation model (DEM) of Upper Lake Mary reservoir. Survey data were collected in April and October, 2024. Lake bathymetry and subaerial shorelines were mapped by boat using a multibeam echosounder system (MBES), a mobile Light Detecting and Ranging (LiDAR) system, and a Global Navigation Satellite System (GNSS) system with radio connection to a base station to achieve a real-time kinematic (RTK) positioning solution while surveying. Additional subaerial topography was mapped by collecting points in areas too shallow for boat navigation and around the lake perimeter using hand-held RTK-GNSS receivers (Data in Attached Files: Lake_Mary_RTK_Survey2024.zip). These three datasets were combined in a Geographic Information System (GIS) to produce the DEM of the lake basin extending up to the elevation of the dam spillway. The resulting DEM can be used for various applications, such as assessing water storage capacity and sedimentation rates, and provide valuable information for navigation safety and aquatic habitat conditions.