In the study the behavior of thick ice field floating on water surface near flat vertical site of the coast or the construction at differences of water level in the reservoir is investigated. The ice field is considered within the model of flat deformation as thick semi-infinite elastic plate on the basis of Winkler type at various options of contact with the coast. Natural supervision and experi-ments testify that even at small, about 10 cm, abate-ment of water level in the reservoir or increase to its (subtime) near the coast in a thick ice field considerable tension arises. Thus essential is ice influence (about a meter thick and more) on coastal constructions, support of bridges, etc. At abatement of water level near the coast there is so-called" hanging site" - the area of strongly intense ice. Further change of water level (20 cm and more) usually leads to fragile destruction in this area, i.e. to the emergence of cracks. The assess-ment of this of "dangerous zone" is extremely important for planning of various works from ice, laying of winter roads, etc. By means of calculations, natural supervision and experiments it is possible to model the nature of contact of ice field with the coast or the construction. It is formulated and solved approximately by the method based on the approximation of unknown functions by Legendre's polynoms, a stationary task about intense and deformable condition of a strip of ice near the coast at abatement of water level. The cases of the strip, free from external loadings and loaded external force were considered. Received decision will quite well qualitative-ly and quantitatively agree with natural supervision and experiments. Namely, the possibility of emergence of the crack in the place of contact of ice with the coast was traced. Natural experiment was made in the port of Dudinka. During unloading of barges, frozen in thick (0.6-0.8 m) ice, the change of the profile of the ice field during emersion of the barge before the emergence of the crack was fixed.