The Castor River runs throughout southeast Missouri. It starts about 10 miles northeast of Fredericktown in the southern corner of Ste. Genevieve County.
The Upper Castor River flows south into the Headwater Diversion Channel and then into the Mississippi River.
The Lower Castor River flows south of the Diversion Channel and into the Little River.
The name Castor is derived from French, meaning beaver. There are many places to enjoy all along the Castor River especially the Castor River Shut-Ins, also known as Pink Rocks, at Amidon Conservation Area.
If you have never been to the Castor River Shut-Ins, you have to go there. They are similar to Johnson Shut-Ins only with pink rocks and no crowds.