Central Maui’s water story is more complicated—and more controversial—than it looks at first glance. On paper, groundwater pumping is over the official limits, yet state regulators themselves admit those limits may be out of date and “conservative,” which opens the door to very different interpretations of what’s truly safe.
How this debate started
The current discussion flared up after an Oct. 28 staff briefing to the state Commission on Water Resource Management, which focused on how a long, severe drought in East Maui has strained water supplies. During this meeting, staff explained that East Maui has been facing what they described as an “extreme drought,” following an already “extremely dry” period earlier in 2025. As surface water dwindled, concerns naturally shifted toward how much pressure was being put on the underground aquifers that back up the system.
Under an existing agreement, East Maui Irrigation (now fully owned by the agricultural company Mahi Pono) must give priority to the county Department of Water Supply for household and other domestic uses. Because of that, Mahi Pono has reportedly not received any surface water deliveries since Aug. 28 and has instead turned to groundwater pumped from the Central Maui ʻĪao aquifer system to keep its fields irrigated. Company operations have therefore depended increasingly on wells, and regulators noted that Mahi Pono has been steadily “ramping up” groundwater production to keep agriculture going in the face of the ongoing drought.
Pumping numbers that raised alarms
Things became especially tense when Jonathan Likeke Scheuer, chair of the East Maui Regional Community Board and the Hawaiian Homes Commission representative on that board, voiced serious concern about how much water Mahi Pono was taking from the Kahului and Pāʻia aquifers. He pointed out that reported withdrawals were higher than the officially published “sustainable yield” values, which are meant to represent the maximum long‑term pumping rate that an aquifer can handle without being damaged. For many community members, the idea that current withdrawals exceed those benchmarks is an instant red flag.
Scheuer highlighted figures showing that up to 13 million gallons per day (mgd) had been pumped from the Kahului aquifer, even though its listed sustainable yield is only 1 mgd, and as much as 25 mgd had been drawn from Pāʻia, where the sustainable yield is 7 mgd. Numbers like that naturally sound alarming and can give the impression of a system being pushed far beyond safe limits. But here is where it gets controversial: state officials later clarified that at least some of these figures, such as the 13 mgd for Kahului, represented a single‑day peak rather than a long‑term average.
Daily peaks vs. long‑term stress
Andrew Laurence, communications director for the state Department of Land and Natural Resources, stepped in to clarify how the state actually evaluates groundwater stress. He explained that the Water Commission relies on a 12‑month moving average (often called a 12‑MAV) to understand pumping pressure on an aquifer, rather than focusing on the highest single‑day totals. In practical terms, that means they smooth out seasonal ups and downs—more pumping during dry months, less during wet months—to get a better picture of long‑term trends.
Using this method, the official data shows the Kahului Aquifer averaging about 6.562 mgd compared with its current sustainable yield of 1 mgd, and the Pāʻia Aquifer averaging roughly 13.636 mgd while its listed sustainable yield is 7 mgd. Even by this longer‑term measure, the averages are still above the posted limits, which worries many observers. However, Laurence emphasized that aquifers typically respond slowly to short‑term shifts in pumping and are often resilient to temporary increases, making the 12‑month average a more scientifically useful tool than looking at daily or even single‑month spikes on their own.
Why the “sustainable yield” may be outdated
Here’s the twist most people miss: even though current averages are above the posted sustainable yields, both regulators and Mahi Pono agree that those official yield values may not fully reflect what is happening in the aquifers today. Grant Nakama, Mahi Pono’s senior vice president of business operations, pointed to the state’s 2019 Water Resource Protection Plan, which notes that the sustainable yield values for Kahului (1 mgd) and Pāʻia (7 mgd) were calculated assuming “natural conditions.” In other words, those numbers were based on an aquifer with only natural rainfall and recharge, not one that also receives large amounts of irrigation water soaking back into the ground.
State staff have acknowledged that historically, return flows from irrigation were a major source of additional recharge in Central Maui and that this extra input would directly influence any sustainable yield calculation. That means the currently published sustainable yield figures may be “conservative” and could underestimate how much water these aquifers can actually support under present‑day conditions. Because of this potential mismatch between old models and current realities, the commission’s staff are now collaborating with the US Geological Survey to develop a new groundwater model for the Central Maui aquifer sector that better incorporates today’s land use and recharge patterns. This re‑evaluation could eventually change the official sustainable yield numbers—up or down.
How much water Mahi Pono is using
Nakama has said that, across its Central Maui fields, Mahi Pono’s average groundwater use in 2025 is around 18 mgd, calculated for the period from Jan. 1 through Oct. 31 of that year. That figure includes all of the company’s Central Maui operations and is meant to give a big‑picture view of how much groundwater is supporting its agricultural activities during the drought. However, he also noted that this 18 mgd estimate is not broken out by individual aquifer, which makes it difficult for outsiders to precisely match it against the official Kahului and Pāʻia data.
Nakama suggested that it is reasonable to assume that at least half of that 18 mgd—so roughly 9 mgd or more—comes from the Pāʻia aquifer alone. State officials, however, were careful to say they cannot independently confirm that specific company estimate, because they do not have access to the underlying data set or calculations Mahi Pono used. They also cautioned that the company’s reported average could be based on a different time window or accounting approach, which would make a direct one‑to‑one comparison with the commission’s official 12‑month averages misleading. This difference in datasets is a subtle but important point that often gets lost in public debate.
Competing views on aquifer health
While everyone seems to agree on the general pumping patterns, Mahi Pono and state regulators diverge on what those patterns mean for the aquifer’s health. Nakama has stated that the company sends detailed monthly groundwater‑quality reports to the Commission, covering various indicators meant to show whether the aquifer is being harmed. According to him, these reports so far show no significant negative impact on the broader aquifer, which supports the company’s view that current pumping is still within a safe operating range.
State regulators, on the other hand, are taking a more cautious stance. They are tracking long‑term groundwater‑level trends and watching closely for signs of saltwater intrusion, a process where seawater is pulled inland and upward into the aquifer when pumping is excessive. They are also analyzing data from production wells and dedicated observation wells to see if any slow, subtle changes are taking place below the surface. Officials have stressed that this technical review is still underway and that offering firm conclusions before the analysis is complete would be premature and potentially irresponsible. This careful language reflects the tension between supporting agriculture and protecting a critical public resource.
The legal and regulatory gap
Another quietly controversial aspect is that the Central Maui aquifers are not currently designated as groundwater management areas. Without that formal designation, the state does not have the clear statutory authority it would need to directly regulate pumping levels from these aquifers. That means, for now, there is no full‑scale regulatory cap on how much water individual users like Mahi Pono can withdraw, beyond general rules and reporting requirements.
This situation raises difficult policy questions: Should these aquifers be formally designated as management areas, giving the state stronger tools to limit withdrawals and prioritize uses? Or would that move be an overreaction given that sustainable yield numbers themselves are being re‑evaluated and may prove to have been too low? The answer could shape how Central Maui’s water is shared between agriculture, households, native ecosystems, and cultural needs for decades.
The controversy at the heart of it all
So here’s where it really gets controversial: is Central Maui’s groundwater being dangerously over‑pumped, or are the official numbers simply lagging behind reality and unfairly making the situation look worse than it is? Some people see the gap between reported pumping and sustainable yield as a clear indicator that the aquifers are under serious stress and that stronger controls are urgently needed. Others argue that once new models include irrigation recharge and more current data, the aquifers may still be operating within a safe range, even if the current paperwork says otherwise.
That tension between caution and practicality is what makes this issue so charged. On one side is the fear of long‑term, possibly irreversible damage to a vital water source; on the other is the immediate need to keep farms alive, jobs intact, and local food production viable during a punishing drought. The lack of formal groundwater‑management designation in Central Maui only magnifies the stakes, because it leaves the system more dependent on voluntary reporting, technical analysis, and future policy changes rather than strict, enforceable limits right now.
What do you think?
Given everything here, there is plenty of room for honest disagreement. Do you think the state should act quickly and designate Central Maui’s aquifers as management areas, even before new groundwater models are finished, just to be safe? Or do you believe regulators should wait for updated science and revised sustainable yield numbers before imposing tighter controls that could affect agriculture and the local economy?
Should large agricultural users like Mahi Pono face stricter, verifiable reporting requirements so that company‑reported averages can be more easily compared with official data? And if new models eventually show that sustainable yield is higher than the old conservative estimates, should that be celebrated as good news—or treated cautiously in case future droughts become even more severe?
Share your thoughts: Are current pumping levels an unacceptable risk to a shared public resource, or a reasonable use of groundwater under careful scientific review? Where do you draw the line between protecting the aquifer and supporting local agriculture?
