A 26-year-old man has been arrested after an investigation into an incident in which a man was left seriously injured down a well in Kelmscott.

Det-Sen. Const. Tom Grieve from Mandurah Detectives said the man awoke to find he was at the bottom of a 5m well.

The incident occured on April 13.

The man has been charged with causing bodily harm or danger and is due to appear in Armadale Magistrates court today.