After the flood of Iao Valley
One year ago: The Wailuku River raged - Some repairs have been made; some people in the river’s path are ‘still rebuilding’
Almost a year has passed since one of the largest floods in Maui County’s history destroyed homes, properties and swept up entire landmasses in Iao Valley.
The Sept. 13, 2016, flooding of Wailuku River threatened the lives of several residents, forcing one family to climb onto the roof of its house to safety. The surge of rainwater picked up truck-sized boulders, uprooted giant trees and collapsed parts of Kepaniwai Park and Iao Valley State Monument.
It was the largest recorded stream flow in the valley since 1951. Some have referred to it as a 100-year flood, though data collected from the U.S. Geological Survey estimate it as possibly a 500-year recurrence.
As Hurricanes Harvey and Irma lay waste to the Mainland, county and state officials as well as Maui residents are reflecting on the great flood. No lives were lost in the disaster, but damages to homes, public property and facilities were well over $15 million.
“We’re still here and we’re still rebuilding,” Lisa Higa, whose family was among those hit worst by the flood, said Thursday.
“Everybody has the same story I think. Even my neighbors are still rebuilding.”
How big was it?
Ron Rickman, a retired data section chief for the U.S. Geological Survey’s Pacific Islands Water Science Center, watched his computer monitor in disbelief on the night of the flood. The upstream gauge station was recording data in real time and was climbing rapidly until it suddenly stopped.
“We just thought it was a power problem and needed new batteries,” Rickman said, adding that he sent up a technician the next day. “He walked up the river and said, ‘The whole thing is gone.'”Brian Loving, assistant director of the center, said that the river moved 10,900 cubic feet per second down the valley, or roughly 81,500 gallons per second. It was 200 times as large as the 35-year average for Sept. 13.
The average velocity of Wailuku River during floods exceeds 20 feet per second, or 13 miles per hour, according to an environmental assessment for the Iao Stream Flood Control Modification Project. Video taken the night of the flood shows the river moving possibly faster through Happy Valley.
The river channel near the gauge burst open during the flood, expanding from about 40 feet wide to up to three times the size, Loving said. He said that the destruction of the gauge station makes calculating the speed of the flood, as well as its size, difficult.
Workers do not know how wide or deep the channel was during the peak of the flood, “which would make a big difference,” Loving said. He can say, however, that it was moving fast for water.
“Right now, water is flowing over the left side of the channel, but if it rains it runs over both the left and right side with islands in the middle,” he said. “It’s kind of a mess up there.
“My guess was it wasn’t a big explosion,” he continued. “It came up fast, but came up steady. It wasn’t like you see in the movies — it was probably a little like that, but more steady.”Since the channel is no longer stable, monitoring upstream is impossible, Loving said. He said that a private company is trying to align and stabilize the channel so that a new gauge station can be installed at its original location about 2,000 feet upstream.
Data is temporarily being reported for flood warnings at the Iao Valley Road Bridge near Kepaniwai Park, Loving said. He hopes to reinstall the gauge by November or early December.
The chances of a flood this big occurring again is rare, Rickman said. He said that last year’s flood surprised him “not by just the magnitude, but how localized it was.”
Hydraulic models estimate a 0.2 percent chance, or 500-year recurrence, however it is highly variable because it is taking data from the past 66 years and extrapolating it across 500 years.
“It can happen anytime,” Rickman said. “It’s likely not to, but it certainly could happen.”
One hundred years prior to last year’s flood, a massive surge of water down the same river killed at least 13 Wailuku residents.
The Maui News reported on the Jan. 18, 1916, flood that took out electricity, water and telephone service. The road to Lahaina was washed out in a dozen places, 34 homes were demolished and plantations sustained heavy damage.
The 1916 flood appeared eerily similar to the 2016 one as it hit residents with “so little warning that they had no time to escape,” according to the newspaper report.
“So tremendous was the flood of Iao stream, that it burst its banks in a dozen places and tore its way through stretches of land that never before had been known to be flooded,” the article states. “And so sudden was the rush of the cloudburst in the head of the valley, that for many of the victims escape was cut off before the peril was realized.
“The only marvel now is that several times as many did not lose their lives. Scores escaped by the narrowest possible margin and many owe their lives to the heroic work of others.”
Several families lost their lives in the 1916 flood, including a pregnant woman and her two children. Referred to as only “Mrs. Sodetani, Japanese,” rescuers recovered her body along with her 8-year-old daughter. The body of her 2-year-old child was never found.
Wailuku resident Lloyd Sodetani recalled hearing the story of the flood as a child from his grandfather. He said that the woman was his grandfather’s first wife and they lived near the bridge by Kepaniwai Park.
“The flash flood came and wiped out the house,” Sodetani said. “After his family was swept away, he vowed never to get married again.”
Sodetani said that his grandfather had moved to Maui from Japan and the loneliness of being away from his home country eventually led him to remarry. When the second wife, Sodetani’s grandmother, died, she had directed her son to intern her together with the first wife and daughter at Wailuku Hongwanji Mission.
“You would think the wife would not have anything to do with the first wife, but my grandmother was compassionate enough to do that,” Sodetani said.
Sodetani said that he was not the least bit surprised by last year’s flood, considering his family’s history. He recalled a 1950 flood in Iao Valley that swept away a member of his father’s Boys Scouts troop.
“We’ve had several floods deriving from Iao Stream,” he said. “People don’t realize how dangerous it can be.”
Where are they now?
The Higas’ one-story home filled with water as the river rushed down the valley without warning. The family’s two youngest children and grandmother put on life vests and climbed over a rock feature above their pool to reach the roof.
Lisa Higa rushed home, but stalled outside her front gate as the river flowed over her van. By the time it all ended, her newly renovated home had sustained well over $100,000 in damages, excluding the family’s belongings.
“We all still sleep together in one room, except my oldest,” she said of her three children and husband Stephen. “I know it’s been a year, but if the insurance doesn’t pay for it then we have to pay for it. After losing everything we have, things cost money so as we have time and funding for it we’ll fix our house.”
Many of Iao Valley’s residents did not have flood insurance because it is not in the federal flood zone that required any. Higa said that her family has not received any help from insurance, but countless friends and family have assisted with their needs.
She added that life has somewhat returned to normal with friends and family regularly coming over to hang out at the pool.
“We’re in a good place,” Higa said. “Everything worked out because of everyone in the community who helped us with our house or with donations. It was a lot for one family to take on and it’s not something we could’ve done without our friends. We’re very thankful for everything.”
The Wong family was the other family hit hardest by the flood in the valley.
Flora Wong was trapped in the first-floor bedroom of her home as water rose above her waist. She eventually swam to the second floor in utter darkness and waited for rescuers with her husband and elderly father.
Wong said they have not rebuilt the downstairs yet and are working on a grading and drainage plan. She said that a topographical survey has been completed.
While she hopes to rebuild her home soon, she said that her primary focus has been on her health. She was recently diagnosed with cancer and is undergoing chemotherapy at the Kapiolani Women’s Cancer Center on Oahu.
“It’s taken a back seat,” she said of her house. “We are slowly moving, just not at the rate we’d like to.”
Aside from destroying homes and property, the flood also wiped out about a half-mile of fencing at key chokepoints in the West Maui Mountains’ watershed protection program. The program maintains 22 miles of fence to keep pigs, goats, deer and cattle out of 1,500 acres of pristine watershed.
Program Manager Chris Brosius said that crews and materials have to be airlifted to the damaged areas because they’re too difficult to reach by land. He said that two-thirds of the 50,000-acre project area was damaged by the storm.
The program is short about $140,000 to cover the $265,000 worth of damage. He said they are still trying to acquire funding.
“Repairs are ongoing and we are making them in order of priority based on the amount of pressure from feral animals outside project areas,” Brosius said. “It’s important that we get those fences repaired before they populate the areas.”
The destruction of the riverbed also continues to affect Wailuku Water Co.
President Avery Chumbley said that the channel had solidified over decades, but the flood loosened small rocks and rubble. Debris regularly plugs up gravel traps and the apparatus of Wailuku Water’s system, requiring crews to clean it out by hand.
“Today I had to send guys to Waikapu Valley to clear a gravel trap before the intake,” Chumbley said Thursday. “It filled with rock and rubble to the point where 75 to 80 percent of the water flowed over the trap instead of into the tunnel.”
Chumbley said that crews have cleaned traps at least a dozen times since the flood hit. He said that the Waikapu diversion had fallen to less than 500,000 gallons a day, but has increased to 1.8 million.
“We read the gauges every single day,” he said. “When it starts getting lower, we know the trap is getting fuller.”
Three-quarters of the Iao diversion, which was about 20 feet wide, remains plugged by large rocks and debris, Chumbley said. He said it does not need to be cleaned out because water demand has gone down with sugar cane operations gone.
The diversion will eventually need to be cleared when the county builds its Iao water treatment plant. Chumbley said it could start functioning fully by summer or fall of 2018.
What did we learn?
Several county officials and residents do not feel that more work necessarily needs to be done in order to prepare for a 500-year flood. However, they do agree that communication between various parties needs ample improvement.
The county Department of Public Works spent close to $2.6 million on work and repairs after the flood, which included the flood control facility and bridge by Kepaniwai Park. The facility barely contained the flood, which came within 17 feet of breaking a levee and releasing water throughout Iao Parkside residences and Lower Main Street.
“It did what it was supposed to do,” Director David Goode said. “It was damaged, but it did protect lives and properties.”
When the county came to the Maui County Council for approval of the money spent on emergency work, residents and council members voiced their concerns. Residents and members of Hui o Na Wai Eha, a Native Hawaiian group working to get diverted water restored to West Maui Mountain streams, later questioned county officials about realignment of the river and crushing sacred rocks in the river.
Mayor Alan Arakawa came under fire for saying in a February interview that “there’s no such thing as sacred rocks.”
Hokuao Pellegrino, president of Hui o Na Wai Eha, said that communication from the county, state and other groups could have brought all sides together, rather than divide them. He said that he is still waiting for updates from the state on when officials plan to reinstall water gauges to keep track of Wailuku Water Co.’s water intake.
“If the approach was done more collaboratively on rectifying the issue, things would have been better,” he said. “I think communication is still an issue where the community is not aware of what’s going on.”
Pellegrino thanked the state and county for their work in saving lives and properties, but said that he hopes all sides can learn from the disaster.
“There’s a lot of lessons learned on all levels,” he said.
* Chris Sugidono can be reached at email@example.com.