The main river of the province is the Yaque del Sur. She rises on the Pico Duarte, the highest mountain (3098 meters) of the Caribbean, and flows through the northwest of the province, where she forms a part of the border with the province of San Juan.
Although she has a relatively short flow through the province, she is very important because the water is used to irrigate the arid Plain of Azua. The Las Cuevas river and the Grande river (also called del Medio) are tributaries of the Yaque del Sur and their water sheds are located in the north and northwest of the province.