The drag coefficient for the tangential stress at the interface between freshwater outflow and a salt wedge is estimated by fitting the analytic profile of two-layered salt wedge models to the observed pycnocline. Satisfactory agreement is obtained only if the upper boundary of the pycnocline is chosen to repesent the interface. A best fit procedure gives values of the drag coefficient at this interface between 1.1¿10-4 and 2.7¿10-4. This coefficient is defined by the ratio between the stress and the squared mean velocity of the upper layer. Direct measurements of the Reynolds stress by an ultrasonic current meter give the drag coefficient at the interface as (4.2¿1.4)¿10-4. If the coefficient is defined from the mean velocity of the upper layer relative to the velocity of the sliding interface, it obtains values in the range of 2--7¿103. ¿ American Geophyscial Union 1990