Viscosity measurements are made on aqueous borax solutions of poly(vinyl alcohol) (PVA) samples over a wide range of PVA concentration, C, to examine the hydrodynamic properties of associated polymers compared to those of neutral polymers. The dynamic viscoelastic data are reanalyzed using a statistical-mechanical theory for elastically effective chains in transient gels developed by Tanaka and Ishida. The viscosity data are not superposed in the plot of viscosity against C[eta] using the Huggins relationship, especially around and over a critical concentration, C-N, at which the dynamical behaviors drastically change and an inflection point of a curve in the plot of the viscosity against C is located. On the other hand, when we assume that the chain dimension around C-N is the uperturbed one, the viscosity data around C-N is well-superposed on a curve in the plot of viscosity against C/C-up* where C-up* is the overlapping concentration of the unperturbed chain. The inflection point of this composite curve is located at C/C-up* = 1, which infers that C-N corresponds to the overlapping concentration. All data of the density of elastically effective chains, nu(eff), are superposed on a curve in the plot of nu(eff)/nu against (C-C-N)/C-N where nu is the density of polymer chains, which implies that C-N should be regarded as a kind of gel point. Some discrepancies between the experimental data and the theoretical curve were observed, some of which cannot be explained using the pairwise association of PVA chains.