The Sacachún commune in Ecuador currently faces a lack of water for its agricultural development; this reduces its possibilities of socio-economic development and causes migration to urban areas. This research proposes a presa colinar (hill dam) design that uses ancestral knowledge and classic engineering techniques to promote water use during the dry season in semi-arid regions. The methodology consisted of: (i) a systematic compilation of the ancestral structures used for water planting and harvesting in Ibero-American; (ii) selecting an appropriate place to build the hill dam; (iii) the dam’s body design; (iv) and creating a proposal for agricultural water use. The results helped define a good location for the hill dam implementation. In addition, a 10 m high and 40 m wide earthen dam was designed, with a storage capacity of 114,341 m³, extending agriculture to 7.5 ha through a polyculture system of six different plants. The embankment has a cofferdam located downstream, which provides stability in static and pseudo-static conditions. In addition, the dam slopes have a 2:1 ratio, and a spillway channel and filter drain were dimensioned to protect the dam.