Watertown Regional Airport (IATA: ATY, ICAO: KATY, FAA LID: ATY), formerly Watertown Municipal Airport, is two miles northwest of Watertown in Codington County, South Dakota, United States.

The National Plan of Integrated Airport Systems for 2015-2019 categorized it as a non-primary commercial service facility. Federal Aviation Administration data says it had 4,348 passenger boardings (enplanements) in calendar year 2013, a decrease of 30.5% from 6,254 enplanements in 2012.