The far-field, barotropic effects of in-stream tidal energy extraction from Puget Sound are quantified using a one-dimensional channel model. In-stream turbines are modelled in regions of energetic flow in northern Admiralty Inlet and Tacoma Narrows. The far-field extraction effects include changes to the tide (amplitude and phase), transport, power dissipation, and kinetic power density. These effects are observed throughout Puget Sound and are dependent on the magnitude and location of extraction. The model indicates that a 5 per cent reduction in transport in the South Sound would correspond to either 260 MW of dissipation by in-stream turbines in Admiralty Inlet, 120 MW in Tacoma Narrows, or an intermediate level of dissipation in both locations. The environmental and economic limits on future developments are discussed. For pilot-scale development, this modelling indicates that the barotropic, far-field extraction effects on Puget Sound will be immeasurably small.