Barnegat Township is a township in Ocean County, New Jersey, United States. As of the 2010 United States Census the township's population was 20,936, reflecting an increase of 5,666 from the 15,270 counted in the 2000 Census, which had in turn increased by 3,035 from the 12,235 counted in the 1990 Census. The 2010 population was the highest recorded for the township in any decennial census.What is now Barnegat Township was originally incorporated as Union Township on March 10, 1846, from portions of both Dover Township and Stafford Township, while the area was still part of Monmouth County. It became part of the newly formed Ocean County on February 15, 1850. Portions of the township were taken to form Lacey Township, Ocean Township, Harvey Cedars and Long Beach Township. Union Township changed its name to Barnegat Township as of January 1, 1977.