A coastal river flowing into the sea will create an estuary. The fresh and salt water mix together and this mixture is called brackish water. Brackish water can hold all types of salt water fish along with largemouth bass. Some bass anglers salivate at the chance of catching bass, snook and redfish all in the same place.
Estuaries can go very far up a river or just a short ways. The current, tides and elevation will all play a role in how far the salt water can actually travel up into the river. Rivers on flat terrain will have long estuaries, while the rivers that have higher elevations before the sea will have much shorter estuaries. The bass in the brackish water feed on typical salt water bait fish and shellfish. They will eat mullet, hearing, shrimp and crabs. The time between tidal changes usually provides the best fishing.