Puerto Rico's infrastructure wasn't ready for the serious flooding that Fiona caused

JUANA SUMMERS, HOST:

When Hurricane Fiona stormed across Puerto Rico this week, it dumped a torrent of rain that flooded the island's rivers. The flooding caused catastrophic damage in many communities, and it killed at least one person. As NPR's Adrian Florido reports, the flooding was made worse by a history of poor planning and development, choices that underestimated the complexity and power of Puerto Rico's watershed.

ADRIAN FLORIDO, BYLINE: It was a horrific scene that ricocheted across Puerto Rican media on Monday - a family trapped in their two-story home as a raging river engulfed it.

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UNIDENTIFIED PEOPLE: (Shouting in non-English language).

FLORIDO: Neighbors launched a small motorboat to try to reach the family. On the banks, at least three men gripped a rope attached to the boat so it wouldn't be swept away.

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UNIDENTIFIED PEOPLE: (Shouting in non-English language).

FLORIDO: The house is in the mountain town of Cayey. The river is the La Plata River, which has its headwaters high up in Puerto Rico's central mountains. It winds for more than 40 miles down the mountains before reaching the Atlantic Ocean on the island's northern coast, passing through towns and villages all along the way. For most of the year, the branches and tributaries of this and other rivers all across the island are places Puerto Ricans go to relax, to take a dip in tucked-away watering holes and escape the tropical humidity. But when a large storm comes, Puerto Rico's rivers suddenly become one of the biggest threats to life and infrastructure on the island.

During Fiona this week, gorging rivers swept away houses and bridges. At least two people drowned, including a man whose car was swept away by the Rio La Plata. Some towns got more rain than they've ever gotten from a single storm, more than 30 inches.

MARITZA BARRETO: (Speaking Spanish).

FLORIDO: But Maritza Barreto, a geologist and planner at the University of Puerto Rico, says there are reasons other than the massive rainfall that Fiona caused such catastrophic damage.

BARRETO: (Speaking Spanish).

FLORIDO: All across Puerto Rico, she says, homes, suburbs and shopping centers have been built right up against rivers large and small and in the alluvial valleys that are part of the watershed even if they almost never fill with water. During the construction boom of the 1970s, '80s and '90s, island officials often turned a blind eye to the risks. But Puerto Rico also has many informal communities. Roughly half of the island's housing stock is technically unpermitted construction.

BARRETO: (Speaking Spanish).

FLORIDO: Unfortunately, Barreto, says, people often don't even realize they're building their homes in floodable areas. This week, many people found out.

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PEDRO PIERLUISI: (Speaking Spanish).

FLORIDO: At a briefing, Puerto Rico Governor Pedro Pierluisi said many communities flooded that had never flooded before. The island's public works director, Eileen Velez Vega, said that after Fiona, the government is collecting data to update its flood zone maps.

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EILEEN VELEZ VEGA: (Speaking Spanish).

FLORIDO: Maritza Barreto, the University of Puerto Rico professor, says that keeping communities safe from flooding has to be a continual process here because Puerto Rico's terrain is 75% mountains and is constantly changing. Five years ago, Hurricane Maria uprooted so many trees and caused so many landslides that some rivers shifted their course.

BARRETO: (Speaking Spanish).

FLORIDO: Government efforts to mitigate the risk of future flood damage, she says, has to account for the accumulative effect that development, erosion and ever-larger storms have on the way that Puerto Rico's water flows.

Adrian Florido, NPR News, San Juan. Transcript provided by NPR, Copyright NPR.