Carraízo Dam impounds Loíza Lake which serves as Puerto Rico's main water reservoir.

At the end of the 1940s, the Puerto Rico Aqueducts and Sewers Authority (PRASA) proposed the construction of a dam at the Río Grande de Loíza in the Barrio Carraízo of Trujillo Alto with the intention of providing both water and electricity to the San Juan Metropolitan Area.

As part of the construction, the dam included three hydroelectric turbines with a total capacity of 3 Megawatts for the provision of electricity.

However, during the 1960s and 1970s, the turbines were shut down because their operation and maintenance wasn't considered cost-effective versus the cost of buying energy at the time.

[2] In 1989 Hurricane Hugo caused overtopping of the dam, thereby flooding the hydroelectric facility and rendering it inoperable.