This paper presents dynamic light scattering (DLS) and dynamic viscoelasticity (DVE) studies on transparent aqueous solutions of poly(vinyl alcohol) (PVA) and sodium berate (SE) with a ratio of 2 to 1 by weight fraction. The PVA concentrations, C, of the samples tested are 1.5, 1.8, and 2.0 wt %. The time correlation function, A(q)(t), of light intensity scattered from the samples always exhibits a bimodal distribution of the decay rate, Gamma. The fast and the slow modes are the diffusive modes for the sample with C = 1.5 wt %, slightly higher than the overlapping concentration at 25.0 degrees C. At higher concentrations of C = 1.8 and 2.0 wt %, where the samples behaved like weak gels, the fast and the slow modes are found to be a cooperative diffusion and a relaxation mode, respectively. The characteristic relaxation time, tau(s), estimated for the slow mode is in good agreement with the mechanical relaxation time, tau(M), obtained by fitting DVE data to the Maxwell model with a single relaxation time. The agreement is also gratifying at T = 35.0 and 40.0 degrees C far the sample with C = 2.0 wt %. The results confirm the presence of dynamical coupling between concentration fluctuation and elastic stress in this viscoelastic network system.