Lake Pontchartrain, Louisiana, has two major tidal passes connecting it to the Mississippi Sound and thence to the Gulf of Mexico. The subtidal variability in this system and its relation to wind forcing over a 7-month period were examined.The coherence of water level fluctuations in the lake and passes with those of the sound was high at all times scales, and the water level in all data sets responded to the east-west wind at time scales shorter than 15 days. Since the local coastline is approximately in the east-west direction, the results suggest a couple coastal ocean-lake response. A linear friction model was developed, and it accounted for most of the observed features.