Allamuchy Township is a township in Warren County, New Jersey, United States. As of the 2010 United States Census, the township's population was 4,323, reflecting an increase of 446 from the 3,877 c…Allamuchy Township is a township in Warren County, New Jersey, United States. As of the 2010 United States Census, the township's population was 4,323, reflecting an increase of 446 from the 3,877 counted in the 2000 Census, which had in turn increased by 393 from the 3,484 counted in the 1990 Census.