Abstract: The intensifying interactions between water and rock in the environmental water around some dam sites in China are studied in the paper. Case studies show that the behaviour of the environmental water have been altered significantly since the dams were built and the reservoirs were impounded. The changes consist in(1)Weak acidification of the water on the bottom of reservoirs;(2) Alkalizationor acidification of the ground water under dam foundations;(3)Discharge of eluates occurring at or near the top of some drainage holes drilled into dam foundation; (4)Dissolutio n of curtains;C5)Growth of local uplift pressure values beyond design ones;etc. All these would have important influcence on dam safety,and therefore should attract enough attention.