Examination of thematic mapper (TM) data has shown that water spectral reflectances observed at the top of the scattering atmosphere are contaminated not only by an intrinsic atmospheric reflectance but also by the reflectance of the surrounding green vegetated land surface when the water surface has a small size. This last effect is called the adjacency (or background, or environment) effect. A theoretical formalism has been used to explain the effects and is validated by being able to simulate the TM observed spectral reflectances. Further consequences on land surface classification are discussed, as well as the impact of the adjacency effect on the method of using water surface for atmospheric correction. ¿ American Geophysical Union 1987