Water management for natural channels is a frequent challenge due to the inefficient usage of water resources. The 2030 Agenda of the United Nations (SDG 6 of sustainable development) focuses its attention on water and sanitation. The Sara Guerrero site, located in the Mocache municipality in Los Ríos province (Ecuador), has issues related to access to drinking water, flood control, and crop irrigation that affect 4300 people and 24,000 hectares. The river overflows throughout the rainy season (late December to early May), whereas there is a noticeable water shortage during the dry season. This project aims to design a multiple-use earth dam on the Vinces River, simulating the resulting flow in extreme cases due to its possible failure. Such a study implies the development of a contingency plan for the preservation of life. It considers (i) dam breach analysis and design, and (ii) hydraulic model development using the ArcMap and HEC-RAS software packages. The design includes a waterproofing system that controls possible leaks and a cymbal spillway, mainly for raw water collection. The generated model showed that the shorter the failure time, the higher the maximum output flow. Modelling revealed that four towns would be affected for a maximum of 31 h in extreme cases. This approach offers comprehensive management for this community with regards to the earth dam and flood control.