The area surrounding the Río Puerto Nuevo has changed dramatically over the twentieth and twenty-first centuries. Between 1964 and 2020, the population in the San Juan Metropolitan Area increased by 165%. As more people moved to San Juan, the mangroves and wetlands surrounding the river were replaced with homes, streets, schools, and businesses.
During the mid-twentieth century, to allow for development for new infrastructure, residential and commercial property, the rivers and streams in the Río Piedras watershed were straightened, diverted, and, at times, fitted with concrete bottoms and sides to guide the flow downstream an into the San Juan Bay (this type of work is called “channelization”). This channelization allowed for people to build close to the rivers and the natural spaces along the riverbanks were converted into roads, parking lots, businesses, and housing to accommodate the ever-growing urban population.
As San Juan continued to urbanize, more the construction of buildings, roads, and parking lots increased the amount of rainwater (also called stormwater) entering the channelized rivers and tributaries. This stormwater runoff, combined with more intense and frequent storms, results in increased occurrences of flooding because the channels are not deep or wide enough to effectively move water downstream to the San Juan Bay.
Approximately 50% of people in the Río Puerto Nuevo Flood Risk Management Project area live in homes with first floor elevations equal to or below the flood stage associated with a 100-year flood event. Although a 100-year flood statistically has a 1% chance of happening in any given year, over the past few years, storms in San Juan have become more frequent and intense. Additionally, the development in the area has increased the “flashiness” of storms, causing water to rapidly rise and recede in the channels, which increases flooding risk. Overbank flooding from the Río Puerto Nuevo presents a life safety and economic hazard to a significant portion of the population within the San Juan Metropolitan area, especially during flash flood events.
The primary purpose of this project is to reduce flood risk to people and property in the watershed. However, the project also provides significant economic, environmental, and recreational benefits.