Bathymetric contour map, surface area and capacity table, and bathymetric difference map for Clearwater Lake near Piedmont, Missouri, 2017

Clearwater Lake, on the Black River near Piedmont in Reynolds County, Missouri, (fig. 1) was constructed in 1948 and is operated by the U.S. Army Corps of Engineers (USACE) for flood-risk reduction, recreation, and fish and wildlife habitat (U.S. Army Corps of Engineers, [n.d.]). The lake area is about 1,800 acres with about 34 miles of shoreline at the conservation pool elevation of 498 feet (ft). Since the completion of the lake in 1948, sedimentation likely has caused the storage capacity of the lake to decrease gradually. The loss of storage capacity can decrease the effectiveness of the lake to mitigate flooding, and excessive sediment accumulation also can reduce aquatic habitat in some areas of the lake. Many lakes operated by the USACE have periodic bathymetric and sediment surveys to monitor the status of the lake. The U.S. Geological Survey completed one such survey of Clearwater Lake in 2008 during a period of high lake level using bathymetric surveying equipment consisting of a multibeam echosounder (MBES), a singlebeam echosounder, 1/3 arc-second National Elevation Dataset data (used outside the MBES survey extent; https://nationalmap. gov/elevation.html), and the waterline derived from 2008 aerial light detection and ranging (lidar) data (Richards, 2013). In May 2017, the U.S. Geological Survey, in cooperation with the USACE, surveyed the bathymetry of Clearwater Lake to prepare an updated bathymetric map and a surface area and capacity table. The 2008 survey was contrasted with the 2017 survey to document the changes in the bathymetric surface of the lake.