As a historic Kona low clears the Hawaiian Islands, Maui County engineers are assessing damage that the Hawaii Department of Transportation (HDOT) preliminarily estimates at about $23 million statewide, about $7 million in Maui alone, the Honolulu Star-Advertiser reported.
The storm, which began pounding Maui County on March 11, drew its destructive force from an atypical southwesterly moisture feed characteristic of the Kona lows: slow, upper-level low-pressure systems that can produce extreme rainfall from directions that Hawaii’s drainage infrastructure was never designed for.
The National Weather Service in Honolulu reported five-day rainfall totals topped 44 inches in Upcountry Maui, breaking records dating back to 1951. Wind gusts of 70 mph were reported at Kaunakakai on Molokai, also part of Maui County. The storm hit already compromised ground.
“Prior to this storm, we had three other storms that already hit the islands to pre-soak, knocking over our vegetation,” HDOT Director Ed Sniffen told the Star-Advertiser. Maui County Mayor Richard Bissen signed an emergency proclamation on March 10; Gov. Josh Green (D) later declared a statewide emergency, according to the Governor’s Office.
Bases, buttresses and the threat of noise below
Stormwater collapsed sections of road and broke sewer and water lines in Kihei, Maui Emergency Management Agency (MEMA) Deputy Administrator Kono Davis said. The Hana Highway, one of the world’s most famous coastal routes, was reduced to one lane after multiple roadblocks, HDOT confirmed, and the Honoapiilani Highway was closed for a formal bridge integrity assessment.
The Iao Stream Bridge, which caused public concern during the storm, was inspected and cleaned, with a visible crack traced to the expansion joints documented in its 2024 biennial inspection rather than new storm damage, HDOT said.
Hana lost power and was temporarily isolated by landslides, county officials said, and a water main break in Upper Kula required the emergency deployment of portable tanks for drinking water.
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After the storm, HDOT engineers conducted statewide bridge inspections focused on scour — the erosion of stream bed material around bridge footings and abutments driven by high-velocity floodwater, which the department identifies as a primary structural threat to bridges during floods.
A 5-day cumulative rainfall forecast issued by the National Weather Service in Honolulu on March 11, 2026, shows Maui County among the hardest hit areas, with peak rainfall expected Thursday night into Saturday. Actual totals exceeded forecast levels, with NWS recording more than 44 inches in Upcountry Maui over five days.
Chart courtesy of National Weather Service Honolulu/NOAA
Inspectors assessed debris lines, checked for creek bed changes and looked for evidence of structure movement or settlement, HDOT said. At the height of the storm, Maui crews were temporarily pulled from work sites after winds grew strong enough to snap trees around them, Sniffen told The Garden Island newspaper.
Sniffen said the agency’s emergency triage protocol prioritizes ports and airports first as critical entry points for aid, followed by hospitals and emergency routes, then the broader highway network. The threat to infrastructure extended beyond roads and bridges.
The flooding occurred along a deeper fault, exacerbated by the deadly wildfires that ravaged the historic town of Lahaina in August 2023, when at least 102 people died and more than 2,200 structures were destroyed. The Lahaina fire remains the deadliest wildfire in the United States in more than a century. Stormwater resiliency was already listed as an unfinished priority in the county’s December 2024 Long-Term Recovery Plan, according to MauiRecovers.org, and that gap was tapped March 14 when retention basins overflowed, threatening temporary recovery housing.
Sediment coming from unstabilized slopes above the community, increasing the risk to life and property, according to local media. An outside contractor was hired to lower water levels in the basin overnight, but county officials acknowledged the vulnerability remains until the recovery plan’s stormwater upgrades are built.
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“All this is more expensive”
The storm has forced a broader reckoning with Hawaii’s design standards. Many of the state’s drainage systems, bridges and roads were built in the 1960s and sized for weather patterns that no longer reflect today’s conditions, Sniffen told the Star-Advertiser.
A visible crack in the Iao Stream Bridge in central Maui sparked public concern during the March 2026 Kona Low.
Photo courtesy of Hawaii Department of Transportation
These systems were designed for what engineers define as a 100-year storm—a severe rainfall event with a 1 percent chance of occurring in a given year.
“You see, this storm is a 100-year storm, and we had one just three weeks ago,” Sniffen said. Future projects will likely need to be designed for 200- or 250-year events, requiring larger drainage openings and bridge clearances. “All of this makes sense,” Sniffen added, “but all of this is more expensive.”
Hawaii Emergency Management Agency and Maui County officials said damage assessments remain active, with revised numbers expected in the coming weeks. Hawaiian Electric, the state’s main electric company, reported that more than 26,000 customers statewide remained without power as of the afternoon of March 15, with restoration efforts ongoing, according to a news release from HECO.
