Edamalayar or Idamalayar is one of the major tributaries of the Periyar River, the longest river in Kerala, South India. The Idamalayar Dam is built on this river. It originates in the Anamalais of Kerala's Ernakulam district, and flows into Tamil Nadu before re-entering Kerala near Malakkappara and flowing into the Idamalayar Dam. The river joins the Periyar near Kuttampuzha.