After last week’s evacuation of homes below Kaupakalua Dam and Reservoir on Maui, it’s worth noting that tens of thousands of people in Hawaii live in areas vulnerable to the deadly potential of dam failure.
And lots of folks might not even know it.
With climate change threatening to bring more extreme rainfall events, such evacuations could become more common in the coming years, especially considering the state’s aging network of dams, which are in need of hundreds of millions of dollars in repairs and upgrades.
“This is what happens when the weather changes,” Board of Land and Natural Resources Chairwoman Suzanne Case said during a site visit to Kaupakalua in Haiku. “We’re all seeing it now.”
Of the 130 state-regulated dams in Hawaii, 126 are labeled by authorities as having high hazard potential, meaning they could cause death if they fail.
Additionally, more than a third of the dams are rated either in poor or unsatisfactory condition, according to the latest Dam Safety Performance Report for Hawaii by the Association of State Dam Safety Officials.
Most of the rest of the state’s dams, according to that 2018 report, were deemed in fair shape, one step below a satisfactory rating. A fair rating means no existing deficiencies are recognized but that an extreme hydrologic or seismic event could create one.
Kaupakalua is among the dams in Hawaii described as unsatisfactory, and state regulators had already put a target on the 138-year-old facility for its deficiencies.
The owners last year was put on notice to fix a variety of flaws, including the fact that it had no real- time reservoir water level gauge with the readings accessible on the internet as required by state law.
The owners, East Maui Irrigation Co. and Mahi Pono Holdings Inc., were ordered to operate the reservoir empty and keep the dam’s spillway open to allow any water to pass through.
In October the owners applied to remove the dam.
“We’re working closely with (state dam safety officials) and our consultant regarding the closure,” Mark Vaught, EMI’s director of water resources, said in an interview.
While the coronavirus pandemic added an obstacle to the company’s efforts, he said, the dam is now targeted for removal this summer.
But it wasn’t soon enough, as nearly 14 inches of rain pounded Haiku on Monday.
By early afternoon the dam’s spillway couldn’t keep up. Swiftly rising water levels prompted the owner to trigger the dam’s evacuation plan, and Maui County authorities began to move out an estimated 150 households situated below the reservoir.
Hawaii is home to scores of largely privately owned, earthen dams and reservoirs that were built in the plantation era over a century ago to service the sugar industry.
Most of the dams were built in remote areas away from population centers. But over the years people have moved into areas below these reservoirs, turning them into high-hazard facilities.
Although Hawaii’s Dam and Reservoir Safety Program was started in 1987, the state didn’t get serious about regulating until after the Kaloko disaster in 2006. That’s when the earthen dam of the aging Kaloko Reservoir on Kauai collapsed during extreme rainfall and sent a wall of water downstream, killing seven people.
New laws and tougher regulations emerged from the state Legislature in 2007, elevating the state’s oversight of Hawaii’s dams and reservoirs.
“Our budget went from several thousand to over a million,” said Edwin Matsuda, Hawaii’s engineer in charge of the dam safety program.
But bringing dams up to code when they were largely built before dam safety standards were developed has proved to be a challenge, he said. The cost of the upgrades needed across the state stretches into the hundreds of millions of dollars.
“That’s the main hurdle we’re facing,” Matsuda said. “The price for doing these things keeps getting higher.”
Mahi Pono is one of the state’s largest operators of dams and reservoirs, having bought the Maui lands formerly owned by Alexander & Baldwin in 2019. Mahi Pono operates 56 aging reservoirs, most of them in Central Maui.
Most of these reservoirs, however, have not been used since the closure of sugar in 2016, and others have not been used because they do not meet dam safety requirements, the company said in environmental documents in 2019.
Mahi Pono estimated that the system would need $50 million to $100 million in upgrades to put them back into service.
Matsuda said regulating the reservoirs is a balancing act between safety and the benefits they provide in storage for drinking water, flood control, hydroelectric power, recreation and other purposes.
While safety is the top priority, he said, his program is working with owners to establish “reasonable improvement schedules” to meet the current regulations. In the meantime the program is working with the owners to take care of deficiencies through operational restrictions or other types of actions.
The dam safety program’s report to the 2021 Legislature shows that a number of reservoirs on Maui are restricted in how much water they can hold and are under order to enact remediation plans, including Maui Reservoir No. 24, Kapalaalaea Reservoir and Haiku Reservoir.
Asked to discuss the company’s other reservoirs, EMI’s Vaught declined to respond.
All dam owners of high- and significant-hazard potential dams are required to complete an Emergency Action Plan that, among other things, describes the areas that should be evacuated if there is a failure.
In 2018, heavy rain from Tropical Storm Olivia prompted an evacuation warning to about 10,000 Honolulu residents below Nuuanu Dam No. 1 as water levels in the reservoir rose to dangerously high levels.
As the rain from the storm pelted Honolulu, workers siphoned and pumped water out of the 21 million-gallon reservoir, built in 1905 and operated by the Honolulu Board of Water Supply.
Audry Hidano, who lives in Nuuanu, remembers being at a meeting at the time and hearing about the potential evacuation.
“It was scary,” she said.
Hidano found out only later that her Alika Avenue home was in a different evacuation zone: that of Nuuanu Reservoir No. 4, another facility owned by the Board of Water Supply.
Since that time the Board of Water Supply has made a number of improvements at Nuuanu 1, including installing eight siphons that are turned on during major rain events.
“For the past week the siphons have been on and keeping the water level behind the dam very low,” BWS spokeswoman Kathleen Elliot-Pahinui said Friday. “We also have a fire pumper temporarily stationed at the dam if needed.”
There are also plans for long-term upgrades, she said. A consultant is working on the design of the improvements, and construction could start in late 2022.
As for Nuuanu Reservoir No. 4, a project to upgrade and improve the dam is expected to be completed by the end of 2022.
Elliot-Pahinui said she personally grows concerned every time Oahu gets bombarded by rain. She lives in Waialua on the North Shore, which sits in the evacuation zone for the Waiawa Dam, which holds back Lake Wilson 7 miles away in Central Oahu.
“I always get nervous,” she said. “You never know what’s going to happen.”
But Elliot-Pahinui, who is chairwoman of the North Shore Neighborhood Board in Waialua, reached out to Dole, the dam’s owner, on Tuesday to see how the facility was holding up under the heavy rain. She was assured that the dam was in good shape.
While the impact of a potential dam failure has been discussed over the years at the neighborhood board, Elliott-Pahinui said it’s very possible some folks in the town of nearly 4,000 may not be aware of the potential hazard.
Others across the islands may not be aware of how vulnerable they might be, and that’s why the state has set up an online tool that allows people to check to see whether their property sits in a dam evacuation zone.
DO YOU LIVE IN A DAM EVACUATION ZONE?
To check whether you live in a vulnerable area, go to dlnreng.hawaii.gov/dam/training/am-i-in-a-dam-evacuation-zone.
