Harrison Bay is the home of the Scowlitz (Scaulits) people, whose main reserve is on the bay's western shore, across from Harrison Mills, and also of the Sts'Ailes or Chehalis people, whose reserve is located on the north side of the bay along the lower Harrison River and around that river's confluence with its tributary, the Chehalis.
Harrison Bay is inhabited by two Indigenous groups: the Scowlitz (Scaulits) who reside primarily on the western shore, across from Harrison Mills, and the Sts'Ailes or Chehalis people whose reserve is situated on the north side of the bay along the lower Harrison River and near its confluence with the Chehalis.