Newellton is a town in northern Tensas Parish in the northeastern part of the U.S. state of Louisiana. The population is 1,227 in the 2010 census, a decline of 255 persons, or 17 percent, from the 2000 tabulation of 1,482. Newellton in 2010 was 51 percent African American; in earlier census reports it had been 60 to 65 percent black. The average age of the population there is 41 years.Newellton is west of the Mississippi River on Lake St. Joseph, an ox-bow lake. Further south toward St. Joseph, the parish seat of government, is another ox-bow lake, Lake Bruin, a part of which is the popular Lake Bruin State Park.