The water vapor linestrengths in the region of the 3nu + delta resonance polyad of interacting vibrational states (the corresponding upper states are (310), (211), (112), (013), (131), (230), (032), and (051)) have been analyzed leading to accurate dipole moment transition parameters. The effective rotational Hamiltonian constants used to calculate the vibration-rotation wavefunctions (J.-M. Flaud, C. Camy-Peyret, A. Bykov, O. Naumenko, T. Petrova, A. Scherbakov, L. Sinitsa, 1994. J. Mol. Spectrosc. 183, 300-309) take into account both strong centrifugal distortion effects and dark states presence. These effects are known to be important for the highly excited vibrational states of water-like molecules. The input data set included the line intensities measured by Toth (R. Toth, 1994. J. Mol. Spectrosc. 166, 176-183) and the line intensities of the weak bands 2nu1 + 3nu2, 3nu2 + 2nu3, and 3nu1 + nu2 derived from peak absorptions of a spectrum recorded at a pressure of 17.0 Torr and a path length of 434 m. The parameters of the effective dipole moment operator determined by least square fitting give a very satisfactory agreement with experimental values since the mean error for the 876 experimental linestrengths is only 3.9%. It is worth noticing that such an agreement could be reached only because high-order resonance couplings with dark states were explicitly taken into account. Copyright 1997 Academic Press. Copyright 1997Academic Press