Thousands ordered to evacuate as Oahu floods put dam at imminent risk of failure

After two powerful storms hit Hawaii last week, officials are warning that one of the largest dams on the island of Oahu is at imminent risk of failure.

Water was flowing over Wahiawa Dam on Thursday morning local time. Authorities issued evacuation notices for two towns, Waialua and Haleiwa, which were already experiencing local flooding but could be inundated if the dam fails.

“We have a little over 4,000 people directly in the dam evacuation zone,” said Molly Pierce, a spokeswoman for the Oahu Department of Emergency Management.

Hawaii Gov. Josh Green urged residents to follow directions from emergency officials.

“If you find yourself in these areas, please evacuate now,” he said in a statement.

The 660-foot-long earthen dam can hold up to 9,200 acre-feet of water (about 4,600 Olympic-sized swimming pools). It is equipped with a 183-foot-wide spillway.

“It could fail,” Pierce said of the dam. “At this point, we don’t have a good way to determine whether this is an imminent risk of failure or just overshoot.”

The dam was built in 1906 and is owned by the Dole Food Company. It holds irrigation water, forming a reservoir named Wilson Lake, but was considered in “poor” condition during a 2020 inspection, according to the Hawaii Department of Land and Natural Resources. The department said in an email Friday that its flood risk management team was not available for interviews because it was dealing with imminent public safety issues.

William Goldfield, Dole Food Company’s director of corporate communications, said in an email that the company is “working closely with authorities and continuing to monitor reservoirs, including Lake Wilson,” with public safety as a top priority.

“The dam continues to operate as designed, with no signs of damage,” he continued.

The State of Hawaii had been in talks for several years to acquire Dole Dam. State records show dam safety officials had been monitoring the structure’s deficiencies for more than a decade.

“In the event of a major storm, the undersized spillway may not be able to pass the likely flood, potentially leading to a rupture if water overtops the dam embankment,” Carty Chang, the state’s chief engineer, wrote in a 2024 letter.

The letter said about 2,500 people would be in danger if the dam fell.

Oahu is expected to remain under a flood watch through Sunday, said Stephen Parker, an NWS meteorologist based in Honolulu.

“We’ve had between 8 and 12 inches of rain in North Oahu in the last 12 to 16 hours,” he said. “It’s hard to find a place where there hasn’t been flooding. »

Nate Serota, a spokesman for the Honolulu Parks and Recreation Department, said there were numerous reports of flooding on Waialua and Haleiwa roads, including a few cases in which authorities sent high-clearance vehicles to rescue people.

Images from Oahu shared on social media showed cars submerged in water and neighbors wading through flooded streets. A house in Mokuleia, on the island’s north coast, was swept away by floodwaters overnight.

This is the second week of intense rains on the Hawaiian Islands. More than 5 feet of rain fell in parts of Maui from March 10 to 16, in what is known as a kona storm, a weather phenomenon in which winds come from the south, driving heavy precipitation toward leeward areas of the islands that are generally more sheltered from heavy rain.

“The ground was still very wet from last weekend’s system. Not much was absorbed,” Parker said Friday.

The current storm, he added, is expected to bring one or two more pulses of rain. Although flow gauges suggested water levels were dropping at Wahiawa Dam Friday afternoon, Parker said, the dam is not out of the woods.

“If we got a large dose tonight, it would reinvigorate this threat,” he said.

Green closed Hawaii state offices and departments Friday, except for emergency management, and sent employees home.

“With catastrophic flash flooding already affecting parts of Oahu, including evacuation orders on the North Shore and potential dam-related impacts, we are taking this situation extremely seriously,” he said. “Closing state offices will allow families to focus on staying safe.”

The extreme rains coincide with a period of wild weather across the United States. California and the desert southwest faced a severe heat wave this week. Arizona’s Lake Martinez reached 110 degrees Fahrenheit on Thursday, the highest March temperature ever recorded in the United States. Earlier this week, heavy snow fell across the Midwest and Nebraska experienced its worst wildfire in history.

This article was originally published on NBCNews.com