Castor Creek or Bayou Castor is a 103-mile-long (166 km)tributary of the Little River in north-central Louisiana in the United States. Via the Little, Ouachita and Red rivers, it is part of the watershed of the Mississippi River.
Castor Creek or Bayou Castor flows from a spring in northern Jackson Parish. Caney Lake in Jackson Parish is a main tributary of Castor Creek or Bayou Castor. This waterway flows southeastwardly into Caldwell Parish, where it turns southwardly, flowing into La Salle Parish and along its boundary with Winn Parish. It passes the towns of Olla, Louisiana (formerly known as Castor Sulphur Springs), Urania, Louisiana, Tullos, Louisiana and joins the Dugdemona River to form the Little River, about 3 miles (5 km) northeast of Georgetown. A small man-made lake is formed near the town of Olla, locally known as the "Spillway" or "The Creek". This lake was formed by earthworks built in the 1960s as a replacement to a bridge over Bayoy Castor on La Hwy 124. The local Economical Development Board chose this project to provide a source of fresh water for economical development in the area. Georgia Pacific Inc utilized and pumped water via underground pipeline to its plywood manufacturing site located between Olla and Urania on LA Hwy 125.