A combination of observations and analytical solutions were used to determine the modifications caused by wind forcing on the residual or non-tidal circulation in an ebb-tidal delta. Observations were obtained in the lower Arcachon Lagoon, southwestern France. The basic non-tidal circulation was established with acoustic Doppler current profilers (ADCPs) that were i) moored in the delta's two deepest channels, and ii) towed along a cross-lagoon transect. The bathymetry of the lower lagoon, or ebb-tidal delta, featured two channels: North Pass (&gt;9 m) and South Pass (&gt;20 m). The basic non-tidal circulation consisted of mostly inflow with weak surface outflow in the South Pass, and laterally sheared bidirectional flow, dominated by outflow, in the North Pass. Analytical solutions and comparison of observed dynamical terms suggested that, in addition to the conventionally accepted influence of tidal nonlinearities, density gradients contributed to the basic non-tidal circulation in the lagoon. Observations also indicated that wind forcing altered the basic circulation by driving simultaneous upwind flows in both passes. This response was supported by an analytical solution to wind-driven flows over the bathymetry of the transect sampled. The response to seaward winds was to enhance inflow in South Pass and reduce outflow in North Pass. Landward winds caused diminished inflow in South Pass and increased outflow in North Pass. This article is protected by copyright. All rights reserved.< Réduire