Thousands have been ordered to evacuate on the island of Oahu after severe flooding raised fears that a major dam could fail. Officials in Hawaii warned that the Wahiawa dam, one of the island’s largest water retention structures, is at risk of imminent overtopping following two intense storms that have saturated the ground over the past week. Water was seen flowing over the dam early Thursday morning, prompting urgent evacuation orders for the nearby towns of Waialua and Haleiwa, both already affected by flooding.

Emergency authorities estimate that more than 4,000 residents fall within the evacuation zone. “It could fail,” said a spokesperson for the Oahu Department of Emergency Management, adding that officials cannot yet determine whether the situation represents imminent structural failure or dangerous overflow.

The dam, built in 1906 and owned by Dole Food Company, holds back irrigation water that forms Lake Wilson. It can store up to 9,200 acre-feet of water and features a spillway designed to release excess flow. However, state inspections have previously rated its condition as “poor,” and engineers have warned for years that the spillway may be too small to handle extreme flood events.

A 2024 letter from Hawaii’s chief engineer noted that in a major storm, water could overtop the dam embankment, potentially leading to failure and placing roughly 2,500 people at risk.

Officials from the National Weather Service said Oahu is expected to remain under flood watch through Sunday. Between 8 and 12 inches of rain fell across northern Oahu in just over half a day, with widespread flooding reported across roads, especially in Waialua and Haleiwa. Rescue operations have already used high-clearance vehicles to assist stranded residents, and social media footage has shown submerged cars and flooded neighborhoods. In one case, a home in Mokuleia on the island’s north shore was swept away.

The situation follows another week of extreme rainfall across the Hawaiian islands. Parts of Maui received more than five feet of rain earlier this month during a kona storm, a weather pattern that drives heavy moisture into typically drier regions. Meteorologists say the already saturated ground has made recent rainfall far more dangerous due to limited absorption.

State officials temporarily closed government offices and sent workers home, except for emergency personnel, as flash flooding and evacuation orders continued on the island’s north shore. Authorities emphasized that the threat remains active, with additional rainfall expected to arrive in pulses that could worsen conditions.

Meanwhile, extreme weather is affecting other parts of the United States. A severe heat wave has gripped areas of California and the desert Southwest, where temperatures near Lake Martinez in Arizona reached record highs for March. At the same time, parts of the Midwest saw heavy snowfall, and Nebraska experienced one of the worst wildfire events in its history.

Officials in Hawaii continue to monitor the dam closely, warning that further heavy rain could quickly escalate the danger again.