This week, the Hawaiʻi State Water Commission is taking up the issue of whether the state should acquire the Wahiawā Dam in Central Oʻahu.
During the recent storms, emergency management officials ordered evacuations in low-lying areas on the North Shore, fearing that the century-old dam was at risk of “imminent failure."
To learn more about the dam and the plantation-era history of irrigation systems, HPR spoke with Carol MacLennan, a professor emerita at Michigan Tech and author of the book "Sovereign Sugar: Industry and Environment in Hawaiʻi."
Interview Highlights
On the history of plantation-era dams
MACLENNAN: These dams at the time were really crucial to sort of the water distribution system, and the water was also used not only for irrigation, but for plantation workers, because now you've got big workforces on these, particularly on the Oʻahu plantations, huge workforces in lots of plantation housing. So you’ve got to have a water supply for that as well. And the Wahiawā Dam was apparently the largest dam built at the time — tallest dam, held the most water. And it was considered to be a major project. And I was just reading that it cost, at the time, about $300,000, which was an astronomical investment for the sugar industry at the time.
On the difficulty of regulating dam safety
MACLENNAN: A lot of states started paying attention to dam safety in the 1970s. And it was, I think, in ‘87 when Hawaiʻi passed the first Dam Safety Act. … So all of a sudden, these dams now have to be inspected. They have to meet standards, and they have to, there has to be a plan for working on that. So then this becomes a regulatory problem. And this is true in all states. You know, this is sort of the normal process of dam safety regulation. The big difficulty that a lot of states have is they don't have the staff to manage these inspections or to enforce the fines if they have fines. … You end up with these dams with this sugar legacy becoming the responsibility of the state government, and then they have to have the regulatory capacity to manage this responsibility.
On acquiring Wahiawā Dam
MACLENNAN: The question that faces the state now is, I understand they're negotiating to buy the dam. So what are they buying? And this is where citizens become really important. And people who, you know, start looking into this, investigative reporters, you know, are they buying this expensive project that they can't afford to fix? So someone has to look at that and make sure that there's a lot of adequate consideration of what the future cost is going to be. … So having a big picture of the dam problem in Hawaiʻi may be an important step for resolving potential issues with other dams, particularly the ones that are the most hazardous at this point in time.
This story aired on The Conversation on March 24, 2026. The Conversation airs weekdays at 11 a.m. Jinwook Lee adapted this story for the web.
