Hawaii Battles Worst Flooding in Two Decades as More Rain Approaches

The Hawaiian islands are experiencing their most severe flooding disaster in over 20 years, with muddy waters forcing 5,500 people to evacuate and causing damage that could exceed $1 billion. Officials warn additional rainfall is expected this weekend while crews monitor a century-old dam that could potentially fail.

HONOLULU — The Hawaiian islands are grappling with their most devastating flood disaster in more than two decades after torrential rainfall pounded ground already soaked from previous winter storms, state officials announced Friday as they cautioned residents to prepare for additional precipitation over the weekend.

Dirty floodwaters engulfed large areas of Oahu’s North Shore, the internationally famous big-wave surfing destination. The rushing waters swept away houses and vehicles, forcing authorities to issue evacuation notices for 5,500 residents living north of Honolulu. Emergency officials expressed concern that a dam constructed 120 years ago might collapse.

Governor Josh Green estimated the disaster’s financial impact could exceed $1 billion when accounting for destruction to aviation facilities, educational institutions, transportation infrastructure, residential properties, and a medical facility in Kula on Maui.

“This is going to have a very serious consequence for us as a state,” Green stated during a press briefing.

The majority of Hawaii remained under flood advisories, while the National Weather Service issued flash flood warnings specifically for Haleiwa and Waialua communities in northern Oahu.

Green reported that his chief of staff contacted federal officials and secured promises of assistance from Washington. No fatalities occurred and everyone was accounted for, though approximately 10 individuals required hospital treatment for hypothermia, he noted.

Search and rescue teams deployed aircraft and watercraft to locate stranded residents, but their operations faced interference from civilian drone operators attempting to photograph the flooding, explained Ian Scheuring, a Honolulu city representative.

Military National Guard units and Honolulu Fire Department helicopters evacuated 72 youth and adults who were participating in a spring vacation camp at Our Lady of Kea’au retreat center on Oahu’s western coastline, according to municipal and camp authorities. While the facility sits on elevated terrain, officials decided against leaving the group there, the mayor explained.

Green characterized the flooding as Hawaii’s most severe since 2004 when Manoa valley floods submerged residences and a University of Hawaii library facility.

Potentially hundreds of dwellings sustained damage Friday, though officials have not completed comprehensive damage evaluations, Honolulu Mayor Rick Blangiardi reported. Approximately 5,500 people received evacuation orders.

“There’s no question that the damage done thus far has been catastrophic,” he stated.

Authorities attributed much of the destruction to the enormous volume of precipitation that fell rapidly on already waterlogged terrain. Sections of Oahu recorded 8 to 12 inches of rainfall during overnight hours. Kaala mountain, the island’s tallest point, measured nearly 16 inches over 24 hours, the National Weather Service reported.

Additional precipitation loomed ahead: Blangiardi announced forecasters predicted 6 to 8 inches would fall across Oahu during the following two to three days.

Weather patterns called “Kona lows,” winter storm systems characterized by southerly or southwesterly winds carrying moisture-rich air masses, caused the recent deluges. Climate scientists indicate that heavy rainfall events in Hawaii have become more intense and frequent due to human-caused global warming.

Emergency managers maintained close surveillance of the Wahiawa dam, which has posed risks for decades, describing it as facing “imminent failure.”

Dam water levels dropped by late Friday, though conditions could deteriorate with additional rainfall. Between Thursday night and Friday, the dam rose from 79 feet to 84 feet, reaching within 6 feet of its maximum capacity, authorities reported.

While preparing to relocate to a friend’s residence on higher elevation, Waialua resident Kathleen Pahinui shared her concerns about the deteriorating dam during every rainstorm.

“Just pray for us,” she requested. “We understand there’s more rain coming.”

State engineers classified the Wahiawa dam as having “high hazard potential,” warning that structural failure “will result in probable loss of human life.”

The earthen structure was constructed in 1906 to support sugar cultivation for the Waialua Agricultural Company, which later became part of Dole Food Company. Engineers rebuilt the dam following its 1921 collapse.

State regulators have issued four deficiency notices to Dole regarding the dam since 2009 and imposed a $20,000 penalty five years ago for delayed safety improvements, according to official records.

Subsequently, Dole offered to transfer ownership of the dam, reservoir and irrigation system to the state in return for the state’s commitment to repair the spillway and maintain safety standards.

Lawmakers approved legislation in 2023 authorizing the dam’s acquisition, allocating $5 million for purchasing the spillway and $21 million for repairs and expansion to meet safety requirements. However, the ownership transfer remains incomplete, with a state board scheduled to vote on the acquisition next week.

“The dam continues to operate as designed with no indications of damage,” Dole stated in an email response.

Hawaii regulates 132 dams statewide, most constructed as irrigation infrastructure for the historical sugar cane industry, according to a 2019 infrastructure assessment by the American Society of Civil Engineers.