An evacuation has been ordered on Oahu as flooding puts a dam at risk of failure
After two powerful hurricanes hit Hawaii last week, officials are warning that one of Oahu’s largest dams is at risk of imminent failure.
Water was flowing at the top of Wahiawa Dam Thursday morning local time. Officials issued evacuation notices for two towns, Waialua and Haleiwa, which were already experiencing localized flooding but could be inundated if the dam fails.
“We have a little over 4,000 people in the evacuation zone,” said Molly Pierce, a spokeswoman for the Oahu Department of Emergency Management.
Gov. Josh Green of Hawaii urged residents to follow the guidance of emergency officials.
“If you are in these areas, please get out now,” he said in a statement.
The 660-foot-tall earthen dam can hold 9,200 acres of water (about 4,600 Olympic-size swimming pools). It is equipped with a 183 meter wide spillway.
“It could fail,” Pierce said of the dam. “Right now, we don’t have a good way to determine whether it’s a risk of near-miss or overshoot.”
The dam was built in 1906 and is owned by the Dole Food Company. It holds irrigation water, creating a lake called Lake Wilson, but is considered to be in “poor” condition during the 2020 assessment, according to the Hawaii Department of Land and Environment. The Department wrote in an email on Friday that its flood risk management team is not available to interview them because they are dealing with public safety issues.
William Goldfield, director of corporate communications for Dole Food Company, said in an email that the company is “working closely with authorities and continues to monitor lakes, including Lake Wilson,” where public safety is paramount.
“The dam continues to function as designed with no signs of damage,” he continued.
The State of Hawaii has been in negotiations to acquire this dam from Dole for several years. State records show that dam safety officials have been tracking the structure for more than a decade.
“In the event of a major storm, a small spillway may not be able to exceed the Potential Flood, which may result in a failure to release water above the dam’s edge,” wrote Carty Chang, the state’s chief engineer, in the 2024 letter.
The letter says that about 2,500 people could be at risk if the dam fails.
Oahu is expected to remain under a flood watch through Sunday, said Stephen Parker, NWS meteorologist based in Honolulu.
“We’ve had 8 to 12 inches of rain on north Oahu in the last 12 to 16 hours,” he said. “It is difficult to find a place where there was no flood.”
Nate Serota, a spokesman for the Honolulu Parks and Recreation Department, said there have been several reports of flooding on roads in Waialua and Haleiwa, including a few cases where officials have sent emergency vehicles to rescue people.
Oahu photos shared on social media showed cars submerged in water and neighbors walking through flooded streets. A village in Mokuleia, on the north coast of the island, was washed away overnight.
This is the second week of heavy rain in the Hawaiian Islands. More than 5 feet of rain fell in parts of Maui from March 10 to 16, during what is known as a kona storm, a weather pattern in which the wind blows from the south, bringing heavy rain to the surrounding areas of the islands that are usually more protected from heavy rain.
“The ground was still very wet from last weekend’s program. Not much of it has absorbed,” Parker said on Friday.
The current storm, he added, is expected to bring one or two more rains. Although streamflow gauges suggested water was receding from Wahiawa Dam Friday afternoon, Parker said, the dam is not out of the woods yet.
“If we get a large dose tonight, it could renew that threat,” he said.
Green closed Hawaii state offices and departments Friday, except for emergency managers, and sent workers home.
“Due to the severe flooding that has already hit parts of Oahu, including evacuation orders on the North Shore and possible dam-related impacts, we are taking this situation very seriously,” he said. “Closing state offices will allow families to focus on safety.”
Heavy rain coincides with a period of wild weather across the United States. California and the desert Southwest have been hot this week. Lake Martinez in Arizona hit 110 degrees Fahrenheit on Thursday, the highest March temperature on record in US history. Earlier this week, heavy snow fell in the Midwest, and Nebraska experienced the worst wildfire in the state’s history.
