Water supply lakes are the primary source of water for many communities in northern and western Missouri. Therefore, accurate and up-to-date estimates of lake capacity are important for managing and predicting adequate water supply. Many of the water supply lakes in Missouri were previously surveyed by the U.S. Geological Survey in the early 2000s (Richards, 2013) and in 2013 (Huizinga, 2014); however, years of potential sedimentation may have resulted in reduced water storage capacity. Periodic bathymetric surveys are useful to update the area/capacity table and to determine changes in the bathymetric surface.
Garden City Lake is a water supply lake used by the city of Garden City in west-central Missouri. The surface area of Garden City Lake is about 30 acres at the flood pool level of the emergency spillway (893.1 feet above the North American Vertical Datum of 1988). A previous bathymetric survey was completed in 2004 with a single-beam echosounder. In July 2020, the U.S. Geological Survey, in cooperation with the Missouri Department of Natural Resources and in collaboration with the City of Garden City, completed a bathymetric survey of Garden City Lake using a multibeam echosounder. The water-surface elevation during the survey was about 891.5 feet. Supplemental data were collected in shallow areas using an acoustic Doppler current profiler (ADCP) mounted on a remote-controlled vessel equipped with a differential global positioning system (DGPS). The echosounder data can be combined with light detection and ranging (lidar) data to prepare a bathymetric map and a surface area and capacity table for the lake. These data also can be used to compare the current bathymetric surface with the previous bathymetric surface.
Based on a comparison of the elevation of coincident points in the 2004 and 2020 surveys (reference mark on the primary spillway wingwall), the 2004 survey data needed to be adjusted upward by 0.013 feet to match the elevation and datum of the 2020 survey. Because of the advances in surveying techniques and accuracy since the previous surveys, it was assumed that the 2020 elevation was the more accurate value.
The gridded bathymetric point data (GardenCityLake2020_bathy_pts.zip) were computed on a 0.82-foot (0.25-meter) grid using the Combined Uncertainty and Bathymetry Estimator (CUBE) method, which is used as the source of points to create the bathymetric surface.
Bathymetric quality-assurance data (GardenCityLake2020_QA_raw.zip) were collected to evaluate the vertical accuracy of the gridded bathymetric point data.
Each of these two zip files contains a shapefile with an attribute table. Attribute/column labels of each table are described in the "Entity and attribute" section of the metadata file.
References Cited:
Huizinga, R.J., 2014, Bathymetric surveys and area/capacity tables of water-supply reservoirs for the city of Cameron, Missouri, July 2013: U.S. Geological Survey Open-File Report 2014–1005, 15 p., https://doi.org/10.3133/ofr20141005.
Richards, J.M., 2013, Bathymetric surveys of selected lakes in Missouri—2000–2008: U.S. Geological Survey Open-File Report 2013–1101, 9 p. with appendix, https://pubs.usgs.gov/of/2013/1101.
