The remains were found by a man who was walking his dog near the wooded property around 5:23 p.m. The land is owned by Trans Alta, and is close to the roadway.
Investigators believe the remains were dumped.
A forensic pathologist for King County will examine the remains to determine its identity, as gender, age, and ethnicity of the remains are not known at this time.
Lewis County Sheriff's Office detectives are investigating, and will check missing person data bases after receiving more information from the forensic pathologist.