A long-term program of continuous measurement of salinities at various locations in Texas estuaries recorded instances of salinity drop and recovery during and after flood inflows. Rates of salinity increase following floods were calculated and compared. Average rates varied from 0.15 psu/day to 0.30 psu/day among bays. The rate of salinity recovery was used with other data to estimate the efficiency of mixing of tidal exchange between Matagorda Bay and the Gulf of Mexico. Results show that approximately 10% of the total tidal influx of new Gulf water is retained in the bay.