  We discuss the impact of dissipation on the development of the energy
spectrum in wave turbulence of gravity surface waves with emphasis on the
effect of surface contamination. We performed experiments in the Coriolis
facility which is a 13-m diameter wave tank. We took care of cleaning surface
contamination as well as possible considering that the surface of water exceeds
100~m$^2$. We observe that for the cleanest condition the frequency energy
spectrum shows a power law decay extending up to the gravity capillary
crossover (14 Hz) with a spectral exponent that is increasing with the forcing
strength and decaying with surface contamination. Although slightly higher than
reported previously in the literature, the exponent for the cleanest water
remains significantly below the prediction from the Weak Turbulence Theory. By
discussing length and time scales, we show that weak turbulence cannot be
expected at frequencies above 3 Hz. We observe with a stereoscopic
reconstruction technique that the increase with the forcing strength of energy
spectrum beyond 3~Hz is mostly due to the formation and strenghtening of bound
waves.
