How Cagayan de Oro’s new ‘run-of-river’ hydro project works

FOR decades, the word “hydroelectric” has conjured images of massive dams, flooded valleys, and dried-up riverbeds. But as Cagayan de Oro seeks to reduce its 70% reliance on fossil fuels, a new project is pitching a different approach: generating power without stopping the river’s flow.

​First Gen Corporation is moving forward with the San Isidro Hydroelectric Power Project (HPP), a 39-40 megawatt facility that utilizes a “run-of-river” engineering scheme. Unlike traditional mega-dams that impound water, this facility is designed to coexist with the Cagayan de Oro River’s ecology—and its famous whitewater rapids.

​A different kind of flow

The project relies on a weir structure rather than a massive reservoir.

​“This design ensures the continuous flow of the river is maintained, diverting only a necessary portion of the water through the facility and immediately returning it downstream,” said Leo Carrillo, First Gen’s project development specialist.

​Carrillo explained that by mimicking the natural flow, the design minimizes disruption to the ecosystem and protects local biodiversity.

​While hydropower is a time-tested technology — the 1.6 MW Agusan Mini Hydroelectric Power Plant has run since 1957 — the San Isidro project represents a modern shift toward “low-impact” design.

​Built for shaking

​The infrastructure spans Barangay San Isidro in Talakag, Bukidnon, and Barangay Tignapoloan in Cagayan de Oro City.

Addressing fears of local flooding or structural failure, the proponents emphasize that they opted for a smaller 40 MW capacity over an originally contracted 160 MW to prioritize safety.

​“This hydro facility will not contribute or worsen flooding in the city,” Carrillo said.

​An Inundation Safety Assessment modeled by Afry, a Swedish energy infrastructure firm, suggests the infrastructure introduces “negligible risk” compared to the city’s existing natural flood hazards.

Carrillo noted that the design exceeds the National Structural Code of the Philippines to withstand strong earthquakes. “We prepared for this absolute worst-case scenario because of the size and critical importance of this facility,” he said.

​Saving the rapids

Perhaps the most critical question for locals was the impact on tourism. A dam that stops the water would kill the city’s whitewater rafting industry.

However, an independent assessment by Diliman Integrative and Consultancy, Inc. confirmed that the run-of-river design will maintain the water levels necessary for rafting. This finding secured the backing of the Oro Association of Rafters.

An AI rendition of First Gen's San Isidro Hydroelectric Power Project. This 39-40 megawatt run-of-river facility is being pitched as a sustainable energy source that respects the ecology of the Cagayan River. Graphics courtesy of First Gen Corporation

“We recognize the importance of clean and renewable energy projects that contribute to local development while protecting the environment,” the association said in its endorsement.

Beyond the rapids, the project triggers a Department of Energy policy (ER 1-94) requiring energy companies to provide financial benefits to host communities. This will result in approximately P0.01 per kilowatt-hour generated going toward local electrification and livelihood funds.