Measurements of tidal and wave water velocities which were made in shallow water near the seafloor in the Strait of Juan de Fuca indicate strong tidal current influence on waves. This effect is reflected in the variation of the velocity frequency spectrum with the direction and magnitude of the tidal current. The area under the spectrum decreases when the current propagates in the direction of the waves, and it increases when the current propagates against the waves. These spectral area variations increase with the current magnitude. The observations are generally consistent with predictions of a spectral model derived from the energy base principle.