Winds and river discharge impact circulation in San Francisco Bay. A model was used to study how wind affects salt intrusion in this estuary. The model showed that tides can change salinity and currents every two weeks. River flow mainly determines the distance salt travels in the bay, while wind can also influence it. In North Bay, circulation changes with river flow and wind, while in South Bay, wind is the main driver. Overall, wind can push the salt boundary further into the bay during low river flow periods.