Do the interim instream flow standards for East Maui need to be revised again to meet off-stream uses in Upcountry and Central Maui? Even when the current flow standards haven’t been fully implemented?
On October 27, the Honolulu Star-Advertiser ran a cover story describing how historic drought on Maui has resulted in lower stream flow in East Maui, forcing the county Department of Water Supply, which relies on water diverted from those streams, to implement unprecedented water restrictions in Upcountry.
The next day, staff hydrologist Ayron Strauch provided more detail to the state Commission on Water Resource Management on the drastically reduced stream flows in East Maui and the consequences for municipal and agricultural uses in Upcountry and Central Maui.
For streams with USGS gaging stations, Strauch showed how flows — from median (also known as Q50) to extremely low (Q95) flows — in the 2022-2025 time period are much lower than they were in the 1984-2013 time period.
For Naʻiliʻilihaele stream, median flows were about 36 percent lower in the 2022-2025 period. Hanawi Stream’s median flows were about 38 percent lower, and Honopou Stream’s median flows were about 40 percent lower in the same period.
Strauch showed photo after photo of other dry East Maui streams taken earlier this year.
“The soils are drying out. If there is a rain event, it doesn’t seep into the ground. No systems recharged in the last six or eight months in East Maui. … In 2025, at the Honopou station, we have 150 days out of 365 that were less than the [Q95] flow. That is as bad as it has ever been,” he said. For 2024, it was 115 days.
East Maui streams have been consistently dry from wet season to dry season, he said.
As a result, the surface water diverted from the streams into the plantation-era irrigation ditch system operated by East Maui Irrigation Company has been insufficient to meet the county’s drinking water needs in Upcountry as well as the irrigation needs of Mahi Pono, which is growing crops on the former sugar lands of Central Maui.
For 2025, Strauch reported, the potable water need in Upcountry was 8.1 million gallons a day (mgd). The median inflow of stream water into the three county Department of Water Supply treatment plants that serve the area was only 5.38 mgd.
“Basically, EMI [owned by Mahi Pono] is operating to serve DWS first. Under drought conditions, DWS may withdraw 6 [million gallons a day]. … Since August 28, Mahi Pono has not received any surface water at all,” Strauch said. (East Maui Irrigation Company diverts water under a revocable permit from the Board of Land and Natural Resources.)
As a result, Mahi Pono has had to pump water from groundwater wells in the Kahului and Paia aquifer systems. “Without this, all of their plants would not survive,” he said.
While Mahi Pono’s use of groundwater had been creeping up in recent years, it spiked this year. In September, Mahi Pono pumped just over 10 mgd from the Kahului aquifer and 25 mgd from the Paia aquifer. The sustainable yields of those aquifers are 1 mgd and 7 mgd, respectively.
Strauch explained why simply using groundwater was not a solution for the county DWS. “Water is heavy, so moving it to higher elevations such as where much of the Upcountry System is located, at 1,000 to 4,000 feet, from basal aquifers at sea level is projected to cost $1.64 per thousand gallons for distribution from the Kamole-Weir [water treatment plant], $4.07 per thousand gallons at the Piiholo WTP, and $5.93 per thousand gallons at the Olinda WTP. [The county’s] current charges for water only average about $4 per thousand gallons,” Strauch said in his presentation to commissioners.
Stream diversions could be modified to capture more high flows for storage, he suggested, but larger and better reservoirs would be required for that. The commission could modify IIFS under low-flow conditions or extreme drought to ensure a reliable water supply for DWS, he added.
Several East Maui streams gain substantial groundwater below the diversions, he noted, and surveys showed that stream fauna may not require full restoration. In fact, he said, they may thrive on flows as lot as H90, which is the amount of flow that provides for 90 percent of natural habitat availability necessary for reproduction, recruitment, and growth.
“You don’t expect to see any difference in biota between H90 and full restoration?” commissioner Lawrence Miike asked.
“Correct,” Strauch replied.
DWS Director John Stufflebean testified that the county planned to increase the capacity of its Kamole treatment plant and to build reservoirs with a total capacity of 140 million gallons. He said the county hoped to construct the reservoirs over the next few years as well. The estimated cost is $25 million, which is almost the department’s entire capital budget of $30 million, he said.
“We are looking for federal funding,” he said.
He added that the county is also considering purchasing or leasing private wells and drilling new county wells. “The wells are going to be expensive and pumping is expensive,” he said.
CWRM deputy director Ciara Kahahane reported earlier in the meeting that the agency was working to drill a deep monitor well in Paia “so we can track what’s going on with the aquifer more accurately. … Ideally, we would be measuring water and chloride levels in a well not actively pumped.”
She added that CWRM had also received funding for the USGS to study Central Maui with the goal of determining more accurate hydrological boundaries.
Commission chair Dawn Chang asked whether the agency has data from Mahi Pono’s wells.
Ryan Imata of CWRM’s groundwater branch replied, “We are not receiving water levels or chlorides for several of their wells. We have reached out to them. We still haven’t received the data. We will reach out and get them in compliance with reporting requirements.”
When it came time for members of the public to testify, attorney David Kimo Frankel, who represents the Sierra Club of Hawaiʻi in a number of court cases involving East Maui stream diversions, argued that Mahi Pono was planting too much of its land in agriculture.
An environmental impact statement for a proposed long-term water license for East Maui water diversions estimated the company would plant 20,000 acres. But Frankel, testifying on behalf of the Sierra Club, said there wasn’t sufficient water for more than 12,000 planted acres.
“[EMI co-owner] A&B incorrectly assumed in its EIS that there was 87.95 mgd it could take from East Maui streams. The Sierra Club has been pointing out for years that this number had no basis. Your staff concludes that based on recent changes in rainfall that much less water is available: 46.9 mgd. And twenty-five percent of the time, only 19.4 mgd will be available. Mahi Pono should not be assuming that it will get more than 30 mgd from East Maui streams. Mahi Pono cannot continue to expand its agricultural operations – unless it wants its crops to wither away and die,” according to the Sierra Club’s written testimony.
It went on to note that, according to University of Hawaiʻi Professor Ali Fares, Mahi Pono’s citrus crops require 2,536 gallons per acre per day. “More than 80 percent of Mahi Pono’s crops are citrus. … 12,000 acres of citrus requires approximately 30 million gallons of water. Twenty-five percent of the time, there will barely be enough water for Mahi Pono’s crops (if you include water from east Maui streams and groundwater and water from streams west of the revocable permit area),” it stated.
In addition, the club’s testimony said, Mahi Pono was over-pumping groundwater.
“For years, the Sierra Club has been asking the Board of Land and Natural Resources to reduce the amount [of East Maui stream water] allocated to Mahi Pono by the amount of groundwater that can be sustainably pumped. In the Paia aquifer, that’s 7 mgd. But recently, Mahi Pono has foolishly been pumping far more than that. Mahi Pono must stop pumping so much water. And stop planting more acres. Instead, it should start conserving water.”
And while it was over-pumping, Mahi Pono was also wasting water by dumping millions of gallons a day of unused stream water into “century-old, unlined, leaky reservoirs,” it continued.
Frankel also argued that, contrary to Strauch’s representations, there was not enough data to suggest that H90 flows produce as much habitat as full restoration. “I think there needs to be a much more rigorous examination of what flow is in each stream and species living there. We need that and don’t have it yet,” Frankel said.
Native Hawaiian Legal Corporation attorney Ashley Obrey, who represents Nā Moku Aupuni o Koʻolau Hui, a group of East Maui farmers and cultural practitioners, expressed concern about how Strauch’s report could be used to take more water from streams. Nā Moku has fought for decades to restore stream flow to East Maui streams.
“There likely could be community pushback,” Obrey said. Mahi Pono plans to expand operations “in this very real crisis,” while the Water Commission’s order regarding interim instream flow standards “still has not been completed,” she added.
On this, Kahahane reported that the state Historic Preservation Division had recently given its concurrence regarding modifications to the diversion system required by the commission.
The Sierra Club noted in its written testimony that many of the diversion modifications that the commission ordered in 2018 and 2022 in were still undone.
“More than a dozen streams are bone dry below the diversions. People live along these streams with no water in them. They are forced to haul water while water is delivered to Mahi Pono miles away,” it stated.
Jonathan Scheuer, a consultant to the state Department of Hawaiian Home Lands and chair of the East Maui Regional Community Board, shared the Sierra Club’s concerns about Mahi Pono’s groundwater use and the continued water diversion from communities experiencing low stream flow.
He also reminded the commission that at some point, DHHL’s water needs have to be factored into the discussion of how off-stream uses are met. DHHL’s use of water is considered a public trust use that has priority over commercial uses such as Mahi Pono’s.
DHHL requested in December 2020 that the commission approve a reservation of East Maui water for the agency’s plans for thousands of acres in Central Maui, but the commission so far has only granted part of it.
Action on the remainder of the DHHL’s request is pending further research by Strauch, Scheuer said. “It’s really important that this happens soon. … To the degree, though I don’t think it’s advisable, that the Board of Land and Natural Resources is considering moving forward towards a long-term lease, the plain language of that statute says you’re supposed have a reservation in place for DHHL before issuing a long-term lease.”
He added that DHHL’s use is “one of the five public trust uses of water, but an off-stream public trust use. Our use should not be coming out of, seen as coming out of reducing stream flows further, but really should be, ‘ok we’ve determined that there might be this much available offstream.’ DHHL’s uses come off of that. Unfortunately, what has happened before and might be suggested by Ayron’s otherwise excellent presentation today is that accommodating DHHL’s uses will only happen if you further take water from East Maui. And I don’t think that’s the process that’s supposed to be followed under the law.”
In cautioning against taking more water from East Maui streams, Scheuer noted that a lot of people on the regional community board from Wailuanui and Keʻanae, where streams have been fully restored, are saying the water is warm and flows are low. Other board members from Huelo have no water in their streams, and at the same time you can see water in the ditch going to Central Maui, he said.
“From a community perspective you’re seeing your community suffer, you’re still seeing water exported and now you’re hearing, ‘Oh, CWRM is thinking about taking more,’” he said.
Chang interjected, “I want to be really clear, there’s no action CWRM is proposing, so I don’t want that narrative to go out that CWRM is proposing to do something.”
“I believe I’m tracking the conversation, including the questions from you,” Scheuer replied. He added that it was great Chang was emphatic that no action was being proposed.
Still, he continued, the talk of taking more water from streams was particularly problematic at a time of deep drought and when Chang, in her role as Land Board chair, had announced she was planning to bring a contested case to move forward with a 30-year water license.
“When Strauch is talking about … ways in which he can take more water out of these streams, it’s inescapable for people to look at that in the context of what you’re proposing for the BLNR. These things are related to each other,” Scheuer said.
He urged Chang, as Land Board chair, to hold off on any long-term license and related contested case and instead “let the community- and Maui-driven processes go forward,” referring to the work of the board he chairs. That board was created in 2022 with the “specific purpose of trying to take over the East Maui irrigation system and operate it as a county, non-potable water utility,” he said. (Chang clarified later that she was proposing not just a long-term license, but also a potential negotiated agreement with county of Maui.)
With regard to Strauch’s take on the biological health of the East Maui streams, Scheuer said CWRM staff’s assessments were just snapshots and did not capture population dynamics over time, including in response to gathering pressure.
Scheuer also encouraged the commission to consider the habitat beyond the streams in any discussion about H90 flow versus full restoration.
“DAR [the state Division of Aquatic Resources] has been looking at the effects of stream flow and ocean life and have seen really significant correlations between healthy corals and restored streams,” he said.
He expressed surprise at the water commissioners’ silence on Mahi Pono’s recent groundwater pumping levels.
He said he appreciated Kahahane reporting that CWRM will be looking at the aquifer boundaries and trying to track salinity. However, he went on to note that not one of the commissioners was jumping up and saying, “Wait! We manage groundwater by sustainable yield and we have a chart in front of us that says we’re, like, ten times over sustainable yield.”
That excessive draw-down “has actually been the case for a long time in Kahului,” he said. “It’s more recent for Paia. I don’t know why there’s not more alarm.”
Scheuer recommended that the commission ask for an update as soon as possible on the groundwater situation in Central Maui, noting that one of the often-touted thresholds to designate a groundwater management area is when pumping exceeds 90 percent of sustainable yield. “You’re at, like, hundreds of percent over sustainable yield. You need to pay some attention to it.”
Mary Ann Pahukoa, whose family has farmed kalo for generations, testified via Zoom from Keʻanae valley. She thanked Frankel, Obrey, and Scheuer for their testimonies.
“This is a very scary time for everybody. I do hope that you can understand our concerns and manaʻo that Ashley and Kimo and Jonathan have shared with you. … This board should be creating some solutions to mandate real-time, slow monitoring. There’s a lot of conflict going on with EMI collecting their own data and presenting it to our community,” she said.
Mahi Pono was misusing the water it was diverting, she added, saying that the company “continues to threaten our way of life. East Maui provides more ulu, kalo, and sweet potato and various crops than Mahi Pono could ever. So when we talk about protecting the public trust or when we talk about providing food security to our islands and to our communities, Mahi Pono does not do this. The East Maui farmers and generational kalo farmers have done this without prioritizing profit.”
In response to some of the testimony calling for more data on ecosystem health in East Maui, Strauch said, “I just wanted to temper expectations. We are in charge of monitoring, at the moment, 120 locations statewide with a team of four. We conduct biological surveys and many, but not all, are at one or more elevations, which takes one or more days.
“We are out of time to add field work. We are lucky enough that we had extra funds this year to purchase helicopter time to get to these locations. The streams are not easily accessible other than if near the highway or via helicopter. We’re not going to go in monthly. We don’t have the time or resources. We’re not going to go in every six months. If we get into a single location every year, that’s a win. That’s just the reality of the situation. We’re never going to understand the monthly dynamics of populations.”
Kahahane added, “We’re going to keep asking for more funding as long as I’m here.”
Chang, in the end, expressed her appreciation for all of the testimony that brought “different levels of expertise and experience to the commission.”
“I think we’ve had the opportunity to vet a lot of issues,” from DHHL needs, to community concerns, to data gaps, she said. “All of this is critical. … I want everyone to know how difficult this is. This isn’t easy, whether you sit as the Water Commission, whether you sit as the Board of Water Supply, whether you sit as the Board Land and Natural Resources. We are all balancing tremendous competing interests guided by some legal uncertainties, but we’re all trying to do the best that we can.”
— Teresa Dawson
(This article has been corrected to reflect that Mahi Pono fully owns EMI. We incorrectly reported that Mahi Pono was co-owner of the irrigation company.)
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