Guayo Dam, also known as Lago Guayo, is a gravity dam located on the Guayo River in Lares, Puerto Rico. Owned by the Puerto Rico Electric Power Authority, this public utility serves multiple purposes including hydroelectric power generation, irrigation, and water supply. Completed in 1956, the dam stands at a height of 190 feet with a storage capacity of 19,000 acre-feet and a surface area of 285 acres.

With a maximum discharge capacity of 30,200 cubic feet per second, Guayo Dam features an uncontrolled spillway with a width of 220 feet. Despite its significant hazard potential and poor condition assessment, the dam is under regular state inspection, enforcement, and regulatory oversight by PREPA. The risk assessment for the dam is classified as moderate, indicating potential vulnerabilities that may require additional risk management measures.

Overall, Guayo Dam presents an intriguing case study for water resource and climate enthusiasts, as it exemplifies the complex interplay between hydroelectric power generation, water supply management, and dam safety in the context of Puerto Rico's unique geographical and regulatory landscape. With its historical significance dating back to the mid-20th century, the dam continues to play a crucial role in the region's water infrastructure, highlighting the importance of sustainable water resource management and resilience in the face of evolving climate challenges.