Most Dams in Hawaii Classified as High Hazard

State officials say 'high hazard' designation reflects downstream development, not likelihood of collapse

Mar. 30, 2026 at 10:05am

Got story updates? Submit your updates here. ›

A sweeping, atmospheric landscape painting depicting a small, partially obscured dam structure dwarfed by the overwhelming power of a violent storm, conveying the sublime scale and potential danger of Hawaii's aging dam infrastructure.Hawaii's aging dam infrastructure faces growing risks from extreme weather, as evidenced by recent near-overtopping incidents that underscore the need for ongoing maintenance and upgrades.Wahiawa Today

Nearly all of Hawaii's regulated dams, 122 in total, are classified as 'high hazard,' meaning their failure could result in loss of life. State officials say this designation reflects the downstream development near these dams, not necessarily the likelihood of the dams collapsing. During a recent storm, several Oahu dams came close to overtopping, raising concerns among residents, though officials maintained the structures 'performed as designed.'

Why it matters

Hawaii's aging dam infrastructure, much of which dates back to the plantation era, poses a growing risk to communities downstream as development has expanded. The 'high hazard' classification is based on the potential consequences of failure, not the structural integrity of the dams themselves, highlighting the need for ongoing maintenance and upgrades to ensure public safety.

The details

Of the 122 dams under state jurisdiction, 115 are classified as high hazard, 5 as low hazard, and 2 as significant hazard. During the recent Kona-low storm, water levels at Wahiawa Dam came within 4.7 feet of overtopping, prompting emergency discussions about potential evacuations. The state's two 'significant hazard' dams are both on Maui and currently rated in poor condition, with unresolved safety issues requiring corrective action. Overall, 87 of the state's high-hazard dams are rated in poor or unsatisfactory condition, with the majority of Hawaii's dams being privately owned, aging earthen embankments more vulnerable to erosion and failure.

  • During the recent Kona-low storm, several Oahu dams came close to overtopping.
  • At Wahiawa Dam, water levels came within 4.7 feet of overtopping.

The players

Department of Land and Natural Resources (DLNR)

The state agency responsible for overseeing and regulating Hawaii's dams, including conducting inspections, issuing enforcement actions, and working with dam owners on compliance measures.

City and County of Honolulu's Department of Emergency Management

The agency that holds authority over evacuation orders, weighing forecasts and logistical factors when determining if and when to evacuate areas near dams.

Wahiawa Dam

A high-hazard dam on Oahu that came close to overtopping during the recent storm, prompting emergency discussions about potential evacuations.

Waikamoi Reservoirs

Two 'significant hazard' dams on Maui that are currently rated in poor condition, with unresolved safety issues requiring corrective action.

Maui Reservoir 82

Another 'significant hazard' dam on Maui that is also currently rated in poor condition, with unresolved safety issues requiring corrective action.

Got photos? Submit your photos here. ›

What they’re saying

“Wherever a dam exists, the potential for an incident or failure will always exist, as is the case with any manmade structure.”

— DLNR

What’s next

DLNR said it is working on developing a public-facing map so residents can determine whether they live in a dam evacuation zone.

The takeaway

Hawaii's aging dam infrastructure, much of which is privately owned and in poor condition, poses a growing risk to communities downstream as development has expanded. The 'high hazard' classification of most dams highlights the need for ongoing maintenance, upgrades, and improved emergency planning to ensure public safety.