The Don river basin has high population density, robust economy, but suffers from lack of water supply in low water level periods and seasons. This fact prompts researchers to study various aspects of the water resource dynamics. The analysis of the water flow volumes is demonstrating the decrease of the maximum spring flood water flows, the increase in the low level season water volumes, the leveling of the water flow volumes throughout the year and lower variance of the yearly water resource fluctuations. The duration of the spring floods and the summer-fall low water periods is increasing, but the flood maximums occur later (by 15-20 days), and the summer-fall low water periods start 15-25 days earlier compared to the previous century. The snow-related spring floods show anomalous patterns in terms of time of onset, duration, and height and shape of the flood wave. Autumn floods are episodic. The small rivers are showing signs of degradation, some of them are disappearing altogether. This is one of the reasons of the water resources depletion and the shift towards the earlier occurrence of the yearly low water level extremums. The low water flows and volumes of the current century pose risks for resource utilization.