The Tred Avon River is a main tributary of the Choptank River in Talbot County on Maryland's Eastern Shore. The river is 17 miles long. The Tred Avon's headwaters are located approximately 2.5 miles southeast of Easton, the county seat. The river flows 5 miles roughly west past the city then widens and flows southwest about 12 miles to the mouth just so…The Tred Avon River is a main tributary of the Choptank River in Talbot County on Maryland's Eastern Shore. The river is 17 miles long. The Tred Avon's headwaters are located approximately 2.5 miles southeast of Easton, the county seat. The river flows 5 miles roughly west past the city then widens and flows southwest about 12 miles to the mouth just south of Oxford at Benoni Point. The mouth is marked by the Choptank River Light, a 35-foot spider in the main channel.