Even in the rainy Koʻolaupoko region of Windward Oʻahu, which stretches from Hakipuʻu to Makapuʻu, there is competition for water when it’s dry.
Over the past several years, efforts to restore taro fields, an ancient Hawaiian fishpond, and the estuary at Heʻeia have come a long way. But the non-profit organizations leading those efforts say they need more freshwater for the pond to function properly, for agricultural plans to be fulfilled, and for the ecosystem to thrive and be more resilient to the effects of climate change.
Staff with the state Commission on Water Resource Management last fall unveiled its proposal to restore at least some of the flow into Heʻeia Stream that for decades has been diverted by a tunnel dug into the underground dike system at Haʻiku.
“This area has incredible the potential to be one of the most prominent biocultural landscapes that features Hawaiian practices and complete restoration from mauka to makai, at least here on Oʻahu, if not the state,” Water Commission geologist Ayron Strauch told said at a commission meeting last September.
The Heʻeia National Estuarine Research Reserve (HNERR), Paepae o Heʻeia, Kakoʻo Oiwi, the Kaneʻohe and Kahaluʻu neighborhood boards, the Office of Hawaiian Affairs, the Hawaiʻi Community Development Corporation, and others have expressed their support for the proposal.
The Honolulu Board of Water Supply (BWS), however, has questioned the some of the commission staff’s conclusions about what influences the stream’s flow, and warned that requiring 1.77 million gallons of water a day to flow in the stream below BWS’s tunnel at all times will affect its ability to serve its customers in the region.
The tunnel is only one of nearly 20 water sources in the region that the BWS relies on. Even so, manager and chief engineer Ernie Lau stated in a November 23 letter to the commission that the BWS lacks flexibility in meeting the needs of customers between Haʻiku Valley and Maunawili Valley because its tunnel and well in Kahaluʻu have been separated from its water system. “[A] connecting 16-inch water line across the Heʻeia wetland has been permanently taken out of service due to pipe erosion, leakage and potential main breaks that would be inaccessible to repair,” Lau wrote.
At the commission’s January meeting, Strauch conceded that the Haʻikū tunnel and well “are important for providing municipal water needs for the Windward district.” However, he noted that the Kaneʻohe Marine Base’s golf course, the BWS’s biggest customer in the region, uses what seems to be an excessive amount of potable water, when recycled water would suffice.
“There are other alternative sources [that] can make up the deficiency of reduced withdrawal from Haʻikū tunnel,” he said.
Commission staff proposed at the January meeting giving the BWS 180 days to figure out how it will meet a proposed interim instream flow standard (IIFS) of 1.77 million gallons a day in Heʻeia Stream below the tunnel. After hearing public testimony, however, commissioners said they wanted things to happen a lot sooner than that, especially since two of them would be leaving the commission in June.
Water Commission deputy director Kaleo Manuel said he would bring a revised proposal to the commission next month, giving current commissioners two months to refine things before formally adopting the new IIFS.
During public testimony, Paepae o Heʻeia executive director Hiʻilei Kawelo, who oversees the care and management of the fishpond, stressed how little water in Heʻeia stream currently reaches the ocean.
The 88-acre pond has three gates along the stream to let water in. The most makai gate functions tidally to let brackish water in. The one more mauka lets in just a trickle of water, Kawelo said.
“Our makaha (gate) is boarded up by two 2-by-12s to not allow freshwater to come into the pond. If we pulled the boards, we would drain the stream. That’s how little water makes its way down to our muliwai. You all know the importance of freshwater to stream and estuarine health and to the fishery of Kaneʻohe Bay. Our third gate, which is most mauka, is completely plugged up. It doesn’t allow water into the stream,” she said.
“One day, hopefully soon, within 180 days, we’ll see an increase in freshwater making its way into our loko iʻa and out into Kaneʻohe Bay,” she said.
In written testimony, she explained, “The balance of fresh water and salt water input is what allows for phytoplankton production and algal growth, thus supplying herbivores like mullet and awa (milkfish), the keystone fishpond fish, food to grow. In addition, there was an ʻauwai (fresh water irrigation ditch) that was constructed traditionally to redirect the once abundant amounts of fresh water from Heʻeia Stream to the southeast corner of the fishpond.”
She continued, “We always wondered why there is so little fresh water in the stream, thinking that through our years of restoration and the removal of invasive vegetation, we would see an increase in the amount of water in the stream. Just recently, it was brought to our attention that water is and has been diverted from Heʻeia Stream since the 1940s. With climate changing before our very eyes, we see sea level rising higher and higher every year. Rising sea levels inundate Heʻeia stream all the way up to Long Bridge quite often. Now, more so than ever before, the amount of instream flow needs to be maximized to give us a fighting chance against the impacts of climate change and help us realize our vision of ʻĀina Momona (abundance) for Heʻeia.”
According to a November report by HNERR, research by University of Hawaiʻi at Manoa Ph.D. candidate Evan Lechner suggest that increased circulation from an influx of fresh water would also improve oxygen and salinity levels in the pond.
Just mauka of the fishpond, another non-profit, Kakoʻo ʻOiwi, has been busy clearing the land and has restored 14 acres of loʻi kalo. Ten more acres are ready for reopening, once enough water is available, and the potential is there to expand loʻi across 100 acres, according to staff with the Heʻeia estuarine reserve.
Kakoʻo ʻOiwi executive director Kanekoa Schultz testified in support of the proposed IIFS via Zoom, from the field.
“Behind me, you can see the wetland and hear the ae‘o (endangered Hawaiian stilt) flying around. That water brings back the habitat for the endangered birds we see. Allowing the water to come back or increase, it gives Kāko‘o ‘Oiwi and our wonderful community a chance to hear the sounds of our ancestors. It allows us to fish, practice our culture,” he said.
A powerpoint by HNERR also noted that loʻi expansion will prevent sediment from reaching the fishpond and bay during storm floods.
HNERR’s Frederick Reppun, who helps coordinate the programs of the non-profits doing restoration work in the area and the Hawai‘i Institute of Marine Biology, said the proposed IIFS “moves us one step closer to the restoration we all want to see. It doesn’t get us there by any means.”
The average flow increase under the new IIFS will be enough to complete some of the immediate lo‘i restoration planned, but in the long term, he said, “we need to look at how we can further increase flow or better use what’s available.”
Schultz said he looked forward to working with the BWS, but said 180 days is almost an entire kalo planting season and asked if the deadline for the agency to prepare to meet the IIFS could be shortened. Or perhaps there could be an interim release of water, the effects of which could be studied while allowing Kakoʻo ʻOiwi a chance to plan ahead, he suggested.
As Kawelo and Schultz pointed out, increasing freshwater flow into Heʻeia Stream will benefit native fish and waterbirds. In its powerpoint, HNERR expanded on those benefits, and also described how insects and the state’s only terrestrial mammal will benefit, as well. (The 1,385-acre Heʻeia estuarine reserve was established in 2017 as part of the National Oceanic and Atmospheric Administration’s National Estuarine Research Reserve System, which is aimed at protecting and studying estuarine systems and includes 29 sites nationwide.)
HNERR’s powerpoint noted that flood modeling indicates that if the baseflow of Heʻeia Stream is restored to pre-1940 levels, the amount of wetland habitat would more than double, from eight acres to 19 acres.
“Recent fish monitoring in Heʻeia shows native populations are only at the stream mouth, with almost 100 percent invasive aquarium fish detected through the wetland and Heʻeia Stream. Native fish, such as ʻaholehole and ʻamaʻama (mullet) were once found throughout the wetland,” it stated.
Juvenile ʻamaʻama move between the stream and estuary daily as conditions allow, and increased streamflow would likely create the deeper, wider channels that they prefer to evade predators, it continued.
Native gobies will also benefit from the more defined channels and habitat connectivity that will result from increased stream flow, it stated, noting that with the mangrove removal and habitat restoration done so far, researchers with HNERR, The Nature Conservancy, and the state Division of Aquatic Resources have observed previously undocumented oʻopu naniha in the area.
HNERR pointed out that the upper reaches of the Heʻeia watershed are critical habitat for the blackline Hawaiian damselfly (Megalagrion nigrohamatum nigrolineatum), and “reductions in streamflow likely limit the available habitat for Megalagrion, particularly during drought periods and in the middle and upper reaches that are prone to drying.”
The organization also suggested that the endangered Hawaiian hoary bat, which commonly forage for water-dependent insects along stream edges, may also benefit from a stream with more water in it.
Referring to Schultz’s testimony from the field, HNERR manager Kawika Winter told the commission, “I almost heard the ae‘o louder than his testimony; and I want to congratulate the [commission] staff because the ability to open up these hearings such that people can testify in their place gives the ‘aina a chance to speak for itself, and we heard the ‘āina testifying right there. I would say the ae‘o are testifying in support of a restoration of stream flow.”
After the Haʻiku Tunnel was drilled, the base flow of Heʻeia Stream dropped from about 2 mgd to about 1 mgd, Strauch told the commission.
“That’s a pretty big percentage,’ commission chair Suzanne Case said.
Strauch said the stream really suffers during the dry season, when less than 300,000 gallons per day flows. “That is a trickle of water and that is affecting the instream values. That’s what we are working on protecting,” he said.
Although the BWS disputes that the tunnel alone is what’s caused the drop in stream flow — noting that flows did not rebound when the tunnel was out of service between 2010 and 2014 — Case said restoring greater flow to Heʻeia was a great opportunity to better understand the impacts of freshwater withdrawals.
“We know a fair amount of about temperature impacts of flow on kalo [warm flow is bad], but on invasive species, I don’t know so much. In fish ponds, does the mangrove stay gone at different salinity levels? What do the waterbirds need in terms of salinity? This is a great place to study that,” she said.
Commissioner Neil Hannahs seemed eager to keep the progress made so far going, as he was involved in the management of some of the lands and worked with some of the non-profits when he was employed by Kamehameha Schools, a major landowner in the area.
“Itʻs been amazing whatʻs happened to date. The potential of this to be iconic, a demonstration and continuing center of learning about our environment [is] very gratifying,” he said.
Winter noted that in addition to the Haʻiku Tunnel, a BWS channel also shunts water out of Heʻeia and into Kaneʻohe. He asked whether the commission is exploring ways to add that water back to Heʻeia Stream.
Strauch said that channel, which takes water from a spring near Haleiwa Joe’s, is a harder engineering challenge. “Iʻm not giving up. This [new IIFS] is maybe step one of multiple steps,” he said.
The BWS’s Lau said he would appreciate the commission’s help in efforts to get the Kaneʻohe Marine Base, which uses an average of 2 mgd, to go back to watering its golf course with recycled water. “We tried to put pressure on them. They have their own time frame,” he said.
Barry Usagawa, program administrator for the BWS, added that conservation is the most cost-effective way to reduce the demand for potable water.
He said there are five large non-residential users in the system: the state hospital, Windward Community College, Pali Golf Course, Hawaiian Memorial Park, and Hawai‘i Pacific University, which will convert to a Castle Medical Center expansion. Aside from conservation, the next less-expensive solution to meet the IIFS is to drill more wells, he said. “But the other side of Hawaiian Memorial Park Cemetery is Kapa‘a Quarry, which has non-water bearing blue rock. The closer you get to Kailua, there’s no chance for finding additional sources. You have a big impoundment at Ho‘omaluhia dam that’s a possibility and would take infrastructure to get water from the dam to the big users, but it’s a cost,” he said.
However the BWS resolves its distribution problems, commissioner Kamana Beamer said he would like to see some action on the IIFS proposal before 180 days.
“Domestic water use is a priority [but] there’s a lot of non-public trust uses going on right now that are affecting the public trust. I think any of the non-public trust users should be notified that there is an upcoming decision by the commission,” he said.
“If we can get important issues addressed, maybe not perfected … we can get it on the agenda by June, if not sooner,” Hannahs added.
— Teresa Dawson