Three-dimensional point measurements of basic water-quality parameters in Hoover Reservoir near Westerville, Ohio, August 25 and 27, 2015.

To better understand the hydrodynamics and water-quality distributions of the lower portion of Hoover Reservoir near Westerville, Ohio, in response to selective withdrawal operations at the dam, the U.S. Geological Survey (USGS) conducted two sets of synoptic surveys of water-quality and velocity in August 2015. On August 25, 2015, the middle intake gates were operational at the dam, while on August 27, 2015, the lower intake gates were operational. These water-quality data were collected with an autonomous underwater vehicle (AUV). The AUV operated in an undulating survey mode between six feet above the bed and the water surface at a dive angle of 15 degrees. Three primary survey paths were programmed, one along the approximate center line of the reservoir from the dam to near the bridge crossing at Smother's Road, and two approximately half way between the centerline and the east and west banks, respectively. A total of 14 surveys (8 center line, 3 west, and 3 east) were completed (5 on August 25, 2015 and 9 on August 27, 2015). These data have been reviewed, edited, and processed according to USGS policy and the methods presented in Jackson (2013). Any data with values of "-9999" are considered bad or missing data and should not be used for analysis. Jackson, P.R., 2013, Circulation, mixing, and transport in nearshore Lake Erie in the vicinity of Villa Angela Beach and Euclid Creek, Cleveland, Ohio, September 11–12, 2012: U.S. Geological Survey Scientific Investigations Report 2013–5198, 34 p., http://dx.doi.org/10.3133/sir20135198.