According to the U.S. Census Bureau , the county has a total area of 768 square miles ( 1,990 km2 ) , of which 763 square miles ( 1,980 km2 ) is land and 5 square miles ( 13 km2 ) ( 0.7 % ) is water .
The county has a total area of 768 square miles ( 1,989.1 km2 ) .