Hawaii has experienced widespread severe flooding, considered the most significant in over two decades, particularly impacting Oahu and parts of Maui. The heavy rainfall led to thousands of evacuations, concerns over the Wahiawa Dam, and an estimated economic impact exceeding $1 billion. Emergency services conducted numerous rescues, and the Hawaii National Guard was activated in response to the conditions.
Widespread Flooding and Evacuations
Heavy rainfall has resulted in extensive flooding across Hawaii, with Oahu's North Shore communities of Waialua and Hale'iwa being significantly affected. Reports indicate that homes and vehicles were submerged by muddy floodwaters. Officials issued evacuation orders for approximately 5,500 residents in areas north of Honolulu, including the Waialua area, due to high risks of road failures and inundation.
In Maui County, evacuation advisories were issued for some Lahaina neighborhoods as nearby retention basins approached capacity. These areas were previously impacted by wildfires in 2023. One evacuation shelter at Waialua High and Intermediate School on Oahu was also evacuated, leading to the relocation of approximately 185 people and 50 pets.
Rescue Operations and Casualties
Emergency responders conducted over 200 rescues of individuals from floodwaters across the affected islands. This included the airlift of 72 adults and children from a youth camp as a precautionary measure. Ten people were hospitalized for hypothermia after being recovered from floodwaters. As of the latest reports, no fatalities or missing persons have been reported.
Wahiawa Dam Concerns
The 120-year-old Wahiawa Dam on Oahu became a focal point of concern due to a "risk of imminent failure."
The dam, classified by the Hawaii Department of Land and Natural Resources as a "high hazard potential dam," indicates that its failure could result in the loss of human life. The 85-foot earthen dam, located approximately 17 miles (28 km) northwest of Honolulu, was originally built in 1906 for sugar production and reconstructed in 1921.
Water levels at the dam increased from 24 to 25.6 meters, reaching 1.8 meters below its full capacity, with water observed flowing over its spillway. Dole Food Company, the dam's owner, had received multiple notices regarding dam deficiencies since 2009 and was fined $20,000 in April 2021 for maintenance failures. The state of Hawaii passed legislation in 2023 to acquire the dam, with the transfer process currently ongoing.
By Sunday afternoon, officials indicated that the immediate threat from the dam had diminished as water levels receded. However, broader hazardous conditions across Oahu, including residential flooding, were considered a significant ongoing concern. Officials cautioned that saturated ground conditions mean minimal additional rainfall could rapidly restore flood levels.
Impact and Response
Governor Josh Green estimated that the total damage from the flooding could exceed $1 billion, impacting infrastructure such as airports, schools, roads, homes, and a hospital.
Hundreds of homes have been affected, with the full extent of the damage still under assessment. Floodwaters displaced homes and vehicles, submerged agricultural areas, and entered grocery stores.
The Hawaii National Guard was activated to assist with emergency response and search and rescue operations, alongside military reserves and the Coast Guard. Governor Green confirmed assurances of federal support from the White House. Honolulu Mayor Rick Blangiardi noted the significant number of affected homes.
Weather Context and Outlook
The severe deluges were attributed to "Kona lows," which are winter storm systems characterized by southerly or south-westerly winds that bring moisture-laden air to the Hawaiian islands. These systems are known for causing torrential rains, hailstorms, thunder, and flooding.
Parts of Oahu received 8 to 12 inches (20 to 30 cm) of rain in a short duration on already saturated ground. Kaala, Oahu's highest peak, recorded nearly 400 millimeters in one day, following 670 millimeters between March 10 and 16.
Meteorologists reported that the most severe storm activity appeared to conclude by Sunday afternoon, with weather patterns shifting from widespread showers to scattered rain across Oahu, Maui County, and Hawaii Island. Projections indicated less than 5 inches (13 cm) of additional rain for Hawaii Island and 1 to 2 inches for other regions. Localized flooding remains possible, but drier and more typical March weather is anticipated by Wednesday. Experts suggest that the intensity and frequency of heavy rains in Hawaii have increased, a phenomenon associated with human-caused global warming.