This data release contains water level displacement data and analytical type-curve matches for selected hydraulic tests that support USGS Open-File Report 2019-1102, "Slug-Test Analysis of Selected Wells at an Earthen Dam Site in Southern Westchester County, New York." In 2005, the U.S. Geological Survey began a cooperative study with New York City Department of Environmental Protection (NYCDEP) to characterize the local groundwater-flow system and identify potential sources of seeps on the southern embankment of the Hillview Reservoir in southern Westchester County, New York. The earthen embankment comprises low-permeability glacial clays that were excavated from the site and rest on a veneer of low-permeability glacial deposits that overlie crystalline bedrock. At least two groundwater-flow zones—one shallow and the other deep—overlie the bedrock at the reservoir. Slug-test data were collected from 12 wells at the Hillview Reservoir during August 2007 and from 25 wells at the reservoir and 1 monitoring well south of the reservoir in northern Bronx County in June 2012. Slug-test data from the 38 screened wells were analyzed using the Bouwer and Rice (1976) method to determine the hydraulic conductivity of the sediments in the groundwater-flow zones. The hydraulic conductivity was determined for one well from slug-test data collected by consultants that was published September 2002.