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Project Benefits

 
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Project Area, 1940
In 1940, the Río Puerto Nuevo flowed north from the Río Piedras through the future location of the Bechara Industrial zone and Port of San Juan. At this time, Quebrada Margarita flowed into mangroves and other natural areas surrounding the Río Puerto Nuevo. Map details: United States Department of the Interior Geological Survey Map, San Juan Quadrangle, 7.5 Minute Series, 1940.

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 the development of the Puerto Nuevo complex, along with new roads, businesses, and neighborhoods, 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, 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 statistically 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.

Map showing the 100-Year Flood Zone in the Río Puerto Nuevo watershed area, highlighting areas where approximately 50% of residents live in homes with first floor elevations at or below flood stage.
DOWNLOAD IMAGE

100-Year Flood Zone
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. This project will reduce the risk of flooding to homes and businesses located within this flood zone.

 

Economic Development Benefits

After construction, a reduction in flood risk to homes, businesses, and local infrastructure like roads and utilities totals an annual estimated benefit of over $125 million (2016 price level). These benefits include savings from damages to homes, roadways, infrastructure like water, sewer, and electrical utilities, and impacts to businesses and recreational areas.

Benefits after construction vary by project area. In terms of reduced structural (residential and commercial buildings) damages, this project is estimated to save the region over $84 million (2016 price level) each time a 100-year storm (like Hurricane Maria) impacts San Juan. Given that a 2-year storm causes the Río Piedras and its tributaries to flood nearby streets and buildings, the overall savings that the project provides to people and businesses throughout the region is significant. Additionally, construction of the project is estimated to last for at least ten years. During construction, contractors will hire local workers to manage and build each project phase. Those who are headquartered off the island will require places to sleep, eat, and spend time while not at work. Local manufacturers and suppliers will provide raw material for project construction. Annually, it is estimated that this project will contribute up to $40M (2016 price level) in economic benefits to Puerto Rico during the period of construction.

Additionally, construction of the project is estimated to last for at least ten years. During construction, contractors will hire local workers to manage and build each project phase. Those who are headquartered off the island will require places to sleep, eat, and spend time while not at work. Local manufacturers and suppliers will provide raw material for project construction. Annually, it is estimated that this project will contribute up to $40M (2016 price level) in economic benefits to Puerto Rico during the period of construction.

 

Environmental Benefits

Although the river cannot be returned to its pre-channelized state, when practical, USACE is championing the use of natural designs and materials in its engineering and construction plans to reduce the threat of dangerous flooding to people and property. These solutions include replacing over 30 acres of concrete lining the river with natural materials like rock and sand, reintroducing some river bends to control the flow of the water, and creating more green space and replanting native non-invasive trees to develop finished areas along the river.

 

Site Restoration and Recreational Benefits

After construction is completed on each of the project phases, USACE plans to restore the site by planting trees, grasses, and other natural features. Along the edge of each channel, site restoration may include landscape enhancers like planters or recreational additions such as benches or walking paths. Planters filled with hardy, native annuals and perennials may be installed to beautify the park and provide habitat to insects and animals. Benches and rest areas may line the channels to promote a comfortable and enjoyable experience. As much as possible and within the authority of the project, natural berms, fences, and plants will be used to beautify the channel and natural materials may be incorporated into the concrete channel walls to help them blend into the surroundings.

A recreation analysis was completed as part of the 1992 General Design Memorandum. At that time, the recreation benefits of the project were estimated to be $831,000 (1990 price level). Using updated unit day values, the recreation benefits of the project are estimated to be approximately $1.1 million (2015 price level). These benefits account for the construction of features like the linear park. It is USACE’s goal to work closely with each community to determine what features are most desired in their neighborhood. Learn more and become involved.

Last Updated: July 2025