When Jen Simpson woke just after 1 a.m. on March 20 in Haleiwa, water was already rushing into her bedroom. Within five minutes it reached her knees. Her roommate's boyfriend had to break the door open so she could get out. They moved to higher ground inside the house and waited. The water kept climbing, past her waist, toward her chest. At sunrise, someone called out asking if anyone needed help. They paddled out through the neighborhood on surfboards.
By then, every road in and out of Haleiwa was impassable. Farrington Highway had disappeared under water near Waialua High School. National Guard soldiers were deploying high-water vehicles to evacuate elderly residents from the Kupuna Home O Waialua senior living facility. And the town's drinking water had stopped flowing.
The Sequence
The second Kona Low hit Oahu's North Shore on March 19, nine days after the first storm had already waterlogged the soil and swollen every stream on the island chain. Each failure triggered the next.
Hawaiian Electric cut power across the North Shore. When the grid went dark, so did the Board of Water Supply's pumping stations. The system depends on electricity to pull water from underground aquifers and push it uphill to storage tanks. Without power, the tanks were all that remained. In Waialua, the tanks went dry.
"I think if the power stayed on longer, it wouldn't have been as significant in terms of the water supply, and perhaps a boil water notice would not have been necessary." — Ernie Lau, Board of Water Supply chief engineer
The Board runs nearly 180 pumping stations across Oahu. All of them depend on Hawaiian Electric. One grid, 180 stations, one storm. The boil-water advisory covered Waialua through Haleiwa, Sunset, Pupukea, and out to Turtle Bay, lasting three to four days. For communities already cut off by road, with no power and rising floodwater, "boil your water" assumed access to a working stove.
The Wahiawa Wastewater Treatment Plant exceeded capacity and spilled into Lake Wilson. Schools across Waialua and Haleiwa closed indefinitely. Kahuku Medical Center shuttered its Haleiwa outpatient clinic. Daily life collapsed in sequence: no power, then no water, then no safe way out, then no clinic to reach even if you could drive.
The Dam
Upstream from Haleiwa sits the Wahiawa Dam, an earthen structure built in 1906 to serve a sugar plantation, later a Dole subsidiary. It holds roughly 2.6 billion gallons. The state classifies it as "high hazard potential," meaning failure will result in probable loss of human life. Dole has received deficiency notices since 2009. The spillway was never fixed.
On March 20, the reservoir rose six feet in 24 hours, overtopping the 80-foot spillway and climbing toward the 88-foot crest. Just before 8:30 a.m., Honolulu emergency officials posted an "imminent dam failure" warning. By 9 a.m., water levels had passed 85 feet, three feet below the crest. About 5,500 people were evacuated. The only additional margin was a portable barrier Dole had deployed before the storm, raising the effective height to 90 feet.
"This could wipe out the entire fucking town with billions of gallons in there." — Zaz Dahlin, Haleiwa resident, loading her dogs into her truck after hearing warning sirens at 8:40 a.m. and finding mixed messages from the city, Dole, and old farmers about what level would cause failure.
The dam held.
The Gap
The state is now moving to acquire the dam from Dole and spend upward of $20 million upgrading the spillway to meet current DLNR safety standards. But those standards were written before the rainfall that nearly breached the dam.
Of Hawaii's 131 state-regulated dams, 120 carry high hazard ratings. Most are privately owned. Most are in poor or unsatisfactory condition.
Hawaii DOT's governing standard for road and bridge construction dates to 2005. The preliminary highway damage assessment: $23 million across three islands. Governor Green's disaster declaration documented six dams and reservoirs that activated emergency action plans during the storms. No presidential major disaster declaration has been approved. Without it, the 90% federal cost-share for infrastructure repairs doesn't unlock. And in the public record so far, no engineer, no official, no agency has stated what rainfall standard any of this should be rebuilt to. The debate over whether existing standards are adequate hasn't even started. So the old standards hold by default.
A North Shore resident named Achiu, born and raised in the area, told Civil Beat that watching the water rise used to be something you did for fun. Everyone would go to the bridge. "Now it's just like: 'Crap'."
The old rainfall record is gone. The 180 pumping stations still depend on one grid. The 2005 highway standard is still the standard. The dam is being upgraded to meet requirements written before the storm that nearly destroyed it. Every system on the North Shore broke in sequence because each was designed as if it stood alone. The people living in Haleiwa and Waialua already know they don't.
Things to follow up on...
- Dams built for plantations: Hawaii's 131 state-regulated dams are overwhelmingly relics of the sugar and pineapple era, and 120 of them carry "high hazard" ratings while remaining largely in private hands with poor compliance records.
- Maui's compounding scars: The 200,000-gallon wastewater spill at the Lahaina Reclamation Facility drained through storm channels to the ocean, raising reef contamination concerns in an area where fire-scarred terrain from the 2023 wildfire is accelerating runoff into already stressed waters.
- Kula Hospital's uncertain future: The 116-year-old facility on Maui was evacuated after extensive water damage forced the relocation of approximately 114 patients to other care facilities, and no official has yet said what flood standard a rebuilt hospital would be designed to withstand.
- The disaster declaration wait: Governor Green's formal request for a Major Disaster Declaration was submitted March 23, and as of late March joint preliminary damage assessments with FEMA are still underway with no presidential approval issued.