Abstract: Oceanic lee waves are generated when geostrophic flows interact with rough topography at the bottom of the ocean. These internal waves provide an important sink of energy and momentum from the mean flow, especially in the Southern Ocean. The Drake Passage is an area of high lee wave generation and has been the focus of many lee wave studies due to the rough topography and fast currents in the region. Linear theory with a spectral representation of topography is generally used to predict lee wave generation for use in parameterisations, and has been verified against idealised simulations. Here, we use a realistic wave resolving simulation of the Drake Passage to investigate the utility of such parameterisations for areas of complex large scale topography. The eddying flow is often blocked and split by large amplitude topographic features, calling into question the spectral representation of small scale topography for lee wave generation. We show that the nature of lee waves in such regions can be misrepresented by a spectral approach to topographic representation, leading to both an overestimate of wave energy flux, and an underestimate of wave nonlinearity.