Map: Ground water Aquifer Systems Areas and their sustainable yields (SY) for the Lahaina Aquifer Sector with overlaying surface water hydrologic units and their perennial and intermittent streams with development tunnels and active irrigation ditch systems. Credit: CWRM
By Teresa Dawson
“We just keep getting drier is the bottom line and we’re not making it up,” Ayron Strauch said of the ongoing rainfall deficit in West Maui.
At the state Commission on Water Resource Management’s January 18 meeting, Strauch, a hydrologist with the commission’s stream protection and management branch, joined deputy director Kaleo Manuel in briefing the commission on their rationale for why they believe it should designate the ground and surface water systems in West Maui as water management areas.
Designation, which can be triggered if water resources are threatened or if there are serious disputes over their use, gives the commission the authority to decide who gets to use water in the designated area and how much they should receive via water use permits.
To Water Commission staff, there is no question that the closely linked ground and surface water resources in West Maui area are threatened.
Regarding the rainfall deficit, Strauch explained that from January 2018 through last fall, cumulative rainfall in West Maui has fallen further and further below the long-term average.
Some statistical downscaling models also suggest that whether greenhouse gas emissions stabilize or continue their current increasing trend, the Lahaina aquifer sector, which currently has a sustainable yield of 34 million gallons a day, will see a decrease in recharge.
Under those model scenarios, Strauch said, recharge in the Launiupoko and Honokōwai aquifer areas that lie within the Lahaina sector are projected to substantially decrease, from 10 to 25 percent in next 50-70 years.
These two aquifer systems have a combined sustainable yield of 13 mgd and supply the highly developed resort areas of Lahaina and Kaʻanapali.
Under the state Water Code, designation must occur if there is “an increase in use or authorized planned use that may cause the maximum rate of withdrawal to reach 90 percent of the sustainable yield.”
According to commission staff, that trigger has already been exceeded for the Honokōwai and Launiupoko aquifer systems.
Launiupoko has a sustainable yield of 7 mgd. Current use, development tunnel discharge, authorized planned use, and other permitted well capacity together exceed 8 mgd.
For Honokōwai, with its sustainable yield of 6 mgd, it’s even worse. The same combination of uses and well capacity there exceeds 10 mgd.
For the other four aquifer systems in the Lahaina sector — Honokōkau, Honolua, Olowalu, and Ukumehame — current and potential future uses range from 8 percent of the sustainable yield (at Olowalu) to 71 percent (at Honolua).
Earlier in the meeting, representatives from the U.S. Geological Survey reported some preliminary findings on the potential effects climate change will have on aquifer recharge statewide. The agency has not yet published its results and its presentation to the commission noted that they were subject to revision. Still, commissioners, CWRM staff, and members of the public repeatedly referenced them during the discussion of the proposed designation.
For the Lahaina sector, the USGS reported that a statistical downscaling model using a “business as usual” greenhouse gas emission scenario found that recharge will decline over the next several decades in all six aquifer systems. The models predicted a sector-wide decrease in recharge of 19-24 percent.
The USGS also reported that preliminary results from its dynamical downscaling model found that the Lahaina sector would see a four percent increase in recharge.
In all scenarios, the Ukumehame system, which is the furthest south, will see a drop in recharge of up to 67 percent in the “dry” scenario and down to 4.2 percent in the “wet” scenario. (Dynamical downscaling models rely mainly on input from lower-resolution, global climate models, while statistical downscaling models are informed more by local weather data.)
Conflict
Another trigger for designation is if there are serious disputes over the use of groundwater or surface water. According to commission deputy director Manuel, that is the case in West Maui.
He explained in his report to the commission that after it had amended the interim instream flow standards for six perennial West Maui streams in 2018, “subsequent reductions in the availability of water to meet off-stream demand continue to strain existing water uses, including kuleana tenants and traditional and customary practitioners, and have led to additional conflicts.”
His report goes on to say, “A number of informal (e.g., phone calls, letters, emails) and five formal complaints have been filed with the commission regarding the lack of streamflow, the waste of diverted surface water, the delivery of water, and issues with diversion management from Honokōkau, Honokōwai, Kahoma, Kanaha, Kauaʻula, Launiupoko, Olowalu, and Ukumehame since 2018. In 2020 alone, commission staff have fielded complaints for Honokōkau, Kahoma, Kanaha, Kauaʻula, and Ukumehame streams. The latest is a waste complaint filed for Kauaʻula Stream on December 9, 2021, alleging leakages of water at multiple locations of [Launiupoko Irrigation Company’s] system and a reduction of water delivered for kalo cultivation from the needed 90,000 [gallons per day] to between 47,000-52,000 gpd.”
He and Strauch also noted that because the commission ordered more water to remain in the streams, some users are now targeting groundwater resources. For example, Launiupoko Irrigation Company, Inc. is seeking permission from the Public Utilities Commission to increase its rates for delivering stream water from Launiupoko and Kaua‘ula streams and “pumping of existing and new ground water sources in the Launiupoko aquifer,” according to Manuel’s report.
Manuel explained that in the Lahaina region, where surface water and groundwater are clearly connected hydrologically, establishing an IIFS alone isn’t protective enough. Increased groundwater withdrawals can affect groundwater-dependent ecosystems and coastal discharge, he said.
“So that is one of the impetuses for recommending a coordinated, integrated approach to management and designation here. We’re thinking we’re doing a lot, setting IIFS, but if it’s just shifting the burden to our groundwater resources, then it’s a net zero. It’s not actually helping out in managing resources holistically,” he said.
He also noted that the commission’s current sustainable yield numbers “don’t account for the climate conversation we just had.”
Already, certain wells in the Lahaina sector are exceeding the 250 parts per million chloride levels that are generally considered at the top of what is safe for drinking, he said.
Designation of the groundwater sources would give the commission the ability to regulate the location, spacing, and pumping of wells, he added.
‘Overzealous’
Director of the Maui Department of Water Supply Jeff Pearson — a former deputy director for the Water Commission — did not share his former staff’s view on the need to designate the entire Lahaina sector.
He admitted that the Honokōwai aquifer system may need to be designated, given the apparent threat to the sustainable yield. He added that having just seen Strauch’s presentation, the Launiupoko aquifer system “may also be in jeopardy.”
“Maybe those two aquifer systems should be looked at more closely by the commission and consider designation for those,” he said.But to suggest designation for all surface water and groundwater in West Maui “is a little overzealous. … Just take this slow and look at it from all sides,” he said.
Commissioner Neil Hannahs suggested that the commission would actually be exercising caution if it designated the entire Lahaina sector. He reminded Pearson of the USGS’s bleak projections for future rainfall and aquifer recharge.
“No matter what the current state is today, it’s going to be tested in the future as we look at those projections. So what’s the risk of designating a large area? Why is that an inconvenience? Why is that not cautious?” Hannahs asked.
“You can take cautious too far,” Pearson replied, adding, “Yeah, the predictions of reduced rainfall … are there but that doesn’t mean we need to jump on the bandwagon and designate based on this recent presentation,” he said.
“I’m not going to discount the shortage of rainfall or climate change. I’m not that naive. But I still don’t think we need to jump to conclusions and designate the entire aquifer without additional information,” he said.
He added that well development is ongoing in West Maui and warned that if the commission were to designate the area, well permits could be held up, which could limit or stop planned growth.
Pearson noted that none of the aquifer systems except for Honokōwai and Launiupoko were threatened by current or future authorized planned use. “What is the upside of designating that? … They’re not anywhere near the sustainable yield,” he said.
He said that while the Maui Board of Water Supply favors designation, his office and that of the mayor do not.
The DWS’s Eva Blumenstein added that she would like to see the commission issue more guidance on how groundwater models should be interpreted and used. She also said there should be another monitoring well in Launiupoko to help inform pump distributions. Currently, there is only one.
Public Trust Needs
In response to the DWS’s comments, Strauch pointed out that with regard to surface water, much of it is diverted and managed by private entities, and without designation, the commission has no way of ensuring that public trust needs are met.
Jonathan Likeke Scheuer testified on behalf of the Department of Hawaiian Home Lands in favor of designation. Water uses by the DHHL are a public trust use. If the commission designates the area, the department’s surface and groundwater reservations there would be adopted as an administrative rule, which offers “a layer of protection and assurance DHHL can rely on,” he said.
He also said that the state constitution calls on the commission to take action to protect the public trust long before a crisis develops. He recounted that when the commission designated the ʻIao aquifer more than a decade ago as a groundwater management area, it first debated whether or not to designate the adjacent Waiheʻe aquifer at the same time. Because pumping had not yet reached 90 percent of the sustainable yield in the latter, the commission declined to designate it, he said.
“Really soon afterwards, a private developer came in, saying, ‘We’re putting in wells in the Waiheʻe aquifer right next to the boundary.’ This was the Betsill brothers. … The staff said, ‘Oh my god, we actually don’t want to recommend this permit, but they have correlative rights so we’re not going to deny it.’ …
“The reason why you want to take a comprehensive approach is to avoid people going right outside the boundary line and starting to move your problems and you’re playing whack-a-mole for the next few decades,” he said.
Several native Hawaiian farmers from the area with kuleana rights also testified in support of designation.
Keʻeaumoku Kapu, who lives and grows kalo on kuleana land in Kauaʻula valley, said West Maui should have been designated as a water management area long ago.
“Our ʻohana’s use of water for kalo is protected. … Despite this, we often don’t have enough water in the stream to water our loʻi,” he said, adding that because the population in the area is projected to grow, “it is important to secure our water future for generations to come.”
Kekai Keahi, whose family has kuleana land in Kanaha valley, took issue with the DWS’s claim that designating the entire Lahaina sector would be overzealous. He pointed out that the six aquifer systems that make up the sector don’t have any real hydrologic boundaries between them and the idea that water could be taken from one system for use in another “is one disaster waiting to happen.”
He complained that his family has been waiting for the return of stream water since the commission amended the IIFS in 2018. “The water has never returned. In fact, the county has not put one inch of effort into redesigning the intakes so that we can farm our land,” he said. At the same time, he added, the county is dewatering streams to dilute water from the salty wells in Kanaha that are being overdrawn.
“The designation is something we desperately need,” he said.
Kennard Kaipo Kekona, a farmer in Lahaina, also complained about the amended IIFS not being met and expressed his concern that pending development will force the county to draw from the aquifer systems outside Honokōwai and Launiupoko.
Somewhere close to 40,000 homes are going to be developed in Lahaina, according to the general plan, he said. “We’ve been constantly trying to make efforts to lessen the impact to the community. … The planned growth isn’t considering and factoring what we just looked at today,” he said, referring to the USGS recharge projections.
“I think for us to take a large scope action and grab ahold of that is probably the best … If you cut the lumber too short, you cannot get a board stretcher…. More better have extra than not enough,” he said.
According to Manuel, he plans to bring to the commission a recommendation for some kind of action this month. After holding hearings in March, he said he hoped to make a final recommendation to the commission in April or May.
(For a deep dive on West Maui water issues, see “Water and Power in West Maui,” by Jonathan Scheuer and Bianca Isaki, published last year.)
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