Compelling evidence of structure in liquid water, including its thermal anomalies, high specific heat, low density, and infrared evidence of "tensive intermolecular bonding, and the potential importance of water structure to the biological and earth sciences has stimulated searches for descriptions of water structure for more than a century. This paper reports a new approach. Application of a recently developed viscosity-temperature relation to measured viscosities of water yielded new information about water structure and led to a description of a continuous succession of structure transitions that form as bonding diminishes with rising temperature. The structures are consistent with the observed heat of melting and explain the thermal anomalies, the stability of the supercooled liquid, and the Newtonian behavior of the extensively bonded liquid.