The state is working to jump-start safety upgrades on the privately owned Wahiawa Dam, which last week neared a feared failure point that triggered emergency evacuations for thousands of residents on Oahu’s North Shore.
Ten days before a massive rainstorm generated fear that the 120-year-old earthen dam might fail in the dark morning hours of March 20 and unleash a deadly downstream torrent on much of Waialua and Haleiwa, a state agency issued a request for bids to make safety improvements rebuffed for many years by the dam’s owner.
On Friday, a board guiding the state Department of Land and Natural Resources is expected to authorize DLNR to assume ownership of Wahiawa Reservoir, also known as Lake Wilson, from the dam’s owner, Dole Food Co.
A similar authorization could be given as early as next month by the board of the state Agribusiness Development Corp. to acquire the dam and connected irrigation water system from Dole and another company that owns land under the dam’s spillway.
As part of the water system acquisition, directed by Hawaii’s Legislature via a 2023 state law, the state Department of Agriculture and Biosecurity would be responsible for bringing the dam up to current DLNR safety standards that Dole has failed to meet.
DAB issued its request for dam improvement work bids on March 10.
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The work, which Dole said in 2023 could cost $25 million, includes replacing the dam’s 183-foot-wide spillway with a more efficient new spillway.
A spillway is a critical dam safety feature that allows heavy reservoir inflow above a certain level to pass downstream, and prevent the earthen dam from being over-topped and possibly eroding to a point of complete failure that could uncork over 3 billion gallons of reservoir water into Kaukonahua Stream below.
DLNR considers the existing concrete-lined spillway, which was rebuilt in 1921 after the dam first constructed in 1906 unleashed a flood during a storm, as having an uncertain integrity that could be compromised during a heavy rainstorm.
DLNR, which regulates dam safety in Hawaii, also classifies the overall dam condition as poor due to the spillway and other deficiencies that could lead to the dam being overtopped and failing under what the agency describes as a “probable maximum flood” inundating the reservoir.
Dole contended that this standard is an unrealistic hypothetical more than three times as big as the previous safety standard.
Other parts of the dam rehab work sought by DAB include wall repairs, installation of a debris boom, and excavating a downstream embankment slope that also would receive new drains and rock armoring.
“This project is a high priority for the state,” the agency said in a statement.
DAB estimates that it can have the work, which requires environmental approvals, finished in early 2029, and said it also is exploring how that might be accelerated.
If the work is realized, it would address a decades-long history of flood threats and flood events related to the dam.
Growing concerns
Waialua Sugar Co., a former Dole affiliate, built the dam as part of a system to deliver irrigation water from the reservoir via 30 miles of ditches and tunnels to Central Oahu and North Shore farmland used by the companies to grow sugarcane and pineapple.
Wahiawa dam deficiencies were first identified in a 1978 U.S. Army Corps of Engineers report, according to DLNR.
Concern since then has grown, in part due to the closure of Waialua Sugar in 1996 and more recent declines in Dole pineapple farming that led to a dramatic rise in Lake Wilson water levels fed by two forks of Kaukonahua Stream and treated city wastewater.
After a severe storm in 2002 that caused an estimated $300,000 in damage in Waialua after floodwater releases over the dam’s spillway, Dole agreed with DLNR to reduce the reservoir’s normal maximum water level to 72.5 feet from 82.5 feet.
The dam wall tops out at 88 feet, and the spillway is at 80 feet. Water for irrigation is supplied through lower-level outlets.
DLNR Dam Safety Program officials in 2009 ordered Dole and the owner of land under the spillway, Sustainable Hawaii Inc., to remedy identified issues. But that resulted in Dole producing work on paper while incurring fines and refusing to implement a rehab plan.
As a result, DLNR since 2009 has sent Dole four deficiency notices over dam issues that included a spillway capacity expansion plan, evaluating the stability of an embankment, a work plan and schedule to repair or replace outlet structure gates, responding to dam safety deficiencies identified in a 2008 inspection, delivery of an emergency action plan and failing to start dam improvement work by 2021.
In 2016, the agency restricted the reservoir’s normal water level limit to 65 feet. Then two years later, the agency acquired a portable flood barrier to increase spillway height and dam capacity in case a then-approaching storm, Hurricane Lane, stalled over Oahu. That barrier was deployed ahead of two recent storms to raise the dam wall height to 90 feet.
A further engineering assessment of the dam was commissioned by DLNR in 2020 that identified other potential deficiencies. That led the agency to impose deadlines on Dole for corrective actions that included submitting a dam safety permit application by early 2021 and starting construction by early 2022.
After not meeting the 2021 deadline, Dole was fined $20,000 by DLNR’s board and faced additional possible fines. However, the company, which contested the fine and said it spent $1 million to produce a dam engineering study in 2022, obtained deadline extensions and pursued efforts to sell the water system or have the state take it over.
Offloading effort
Dole, a $9 billion global company that has sold more than $63 million in Hawaii land holdings over the past decade or so, claimed that its Hawaii subsidiary would not be economically viable if forced to upgrade the dam to DLNR’s standard.
The company fell short in a 2022 legislative effort to have the state acquire the dam, reservoir and irrigation infrastructure, but tried again in 2023.
Dan Nellis, Dole Hawaii general manager, told state lawmakers in 2023 that the company would remove the dam and reservoir rather than upgrade the dam.
Such a move would terminate the water supply to Dole’s own roughly 3,000-acre pineapple, coffee and cacao farm operation employing about 200 people, in addition to 50 independent farms with more than 500 workers.
“The decommissioning of this system would be catastrophic to agriculture and food production in Central Oahu,” Nellis said in written testimony on a bill introduced for a state takeover.
Nellis also said dismantling the system would mean the loss of the dam’s benefit to reduce floodwaters from unimpeded mountain streams, and the lake as a public recreation asset where DLNR manages fishing.
Dole proposed giving the system to the state in exchange for receiving up to 6 million gallons of water daily at no cost for its own use.
Lawmakers approved the bill, which became Act 218 in 2023, and directed the Office of the Governor to negotiate terms with Dole and Sustainable Hawaii, a firm owned by retired local attorney and North Shore Marketplace owner Howard R. Green.
Uncertain costs
Act 218 appropriated $5 million to pay Sustainable Hawaii for its property and $21 million for dam rehab work.
The Agribusiness Development Corp. as of February had already executed a purchase agreement with Sustainable Hawaii and anticipated seeking board approval for the Dole dam and irrigation water infrastructure during an expected March 19 meeting, which did not take place.
Dole’s ditch system, which is capable of delivering up to 20 million gallons of irrigation water daily, feeds 17,500 acres of farmland in active production, ADC Executive Director Wendy Gady told board members at the February meeting.
Gov. Josh Green and agency leaders in his administration have said that acquiring the Wahiawa reservoir, dam and irrigation infrastructure is in the public interest to preserve farming, flood control and recreation.
Dole has also suggested that the state with additional investment could produce potable water from the lake and generate electricity with a hydroelectric power plant.
ADC board member Dane Wicker, who is deputy director of the state Department of Business, Economic Development and Tourism, said at the February ADC meeting that the annual economic benefit from the irrigation system was estimated in the early 2000s to be $45 million to $50 million on Oahu.
System benefits, however, likely will come at taxpayer expense beyond $5 million paid to Sustainable Hawaii and $21 million for dam rehab.
DAB said it is working with the governor and the Legislature to address possible higher costs for the dam work. The agency also previously estimated that dam operation and maintenance costs after safety improvements will be $1.5 million a year.
DLNR’s board on Friday is expected to approve the acquisition of the reservoir to ensure long-term protection, management and public benefit of what the agency regards as a “critical water resource” and one of the largest freshwater bodies on Oahu, which plays an important role in the region’s agricultural viability and public safety.
In a report sent to the Legislature in November, DLNR noted that Dole paid its $20,000 fine.
DLNR staff recommends that its board approve the acquisition, saying in a report for Friday’s scheduled board meeting, “State ownership would protect a strategic water resource that is essential to Hawaii’s long-term water security.”
