Members of the state Commission on Water Resource Management continued their investigation into a petition to designate the Keauhou aquifer as a water management area Thursday.
Commissioners kicked off their second one-day visit to Kona with another stop at Kaloko-Honokohau National Historical Park, this time to see the work park staff and volunteers have done to restore Aimakapa fishpond. The site has about 30 acres of wetland, said Sallie Beavers, ecologist and chief of integrated resources for the park. About half of that area is the pond itself, which is fairly shallow, with a sediment layer on the bottom.
Federal officials have designated the pond as a core wetland. Protecting the endangered and native species that live in and around the pond is one of the reasons park officials cited in their petition request. If the commission authorizes the designation, it would create a detailed procedure which almost anyone requesting water access from Makalawena to Kealakekua must complete.
At a Kona Water Roundtable Wednesday, commission staff member Roy Hardy touched on that process in response to a question from the moderator about whether West Hawaii could avoid a contentious designation process, such as the one still happening on Maui, years after the original designation, by getting the designation in place now, well before water use approaches the sustainable yield level.
Hardy said he thought the question was asking whether “by designating, you’ll have less conflict. In my experience, it’s the opposite.”
Ken Kawahara, the former deputy director for the commission, on Wednesday said he doesn’t think the designation is the correct move for the aquifer.
“Why add more regulation if it’s not needed at this time?” Kawahara said. “There’s a cost associated with permits, contested cases, litigation, both time and money. To me, if it’s not an issue now and things can be worked out in a collaborative manner, why add more work to Roy and his group if it’s not needed?”
Kawahara offered an alternative plan, forming a Kona water professionals group to look at existing and proposed water uses.
John Richards, of Waimea Water Services Inc., offered additional insights about the volume of water in the aquifer, the amount being recharged into it and the amount of water being drawn right now. Pumping in the aquifer has increased by about 280,000 gallons annually for the last several years, Richards said. Using that as an annual average increase in the future, it would take more than 80 years for West Hawaii to be pumping 38 million gallons per day, which is the figure state officials have set as the sustainable yield.
“We don’t have to jump to anything right now,” Richards said. “We have time to start monitoring that. … Effects will present slowly. As things change, we can make adjustments. We have to know what’s there, we have to know what’s wrong, we have to know what to change.”
Roundtable attendees were particularly interested in Don Thomas’ presentation on the study of water within the aquifer. Thomas, the direct of the Center for the Study of Active Volcanoes at UH-Hilo, said the isotopic makeup of the water offers a few insights on the water’s origins. Isotopes are atoms of the same element that differ in their numbers of neutrons. Thomas said that the atoms in water, hydrogen and oxygen, can have different weight depending on the number of neutrons, and that the heavier isotopes fall as rain closer to the shoreline, while precipitation at higher elevations is lighter, so to speak.
“The isotopic composition is basically a marker for that rainfall,” Thomas said. “If we sample water somewhere, we can make inferences about … what elevation that water entered the system.”
In looking at the isotopic composition of water in the aquifer, some scientists have said they believe 4 percent of the aquifer is made up of water that falls at higher elevations. Thomas said based on his review of the composition of water in the aquifer, it seems unlikely that it is being recharged primarily through rainfall.
Further, Thomas said, using carbon dating techniques, he’s discovered that the water in several of the South Kona wells is much older than it should be if it were rainfall recharge, based on how the water is flowing. He believes the water may come from sources within Mauna Loa or Mauna Kea.
“(The) evidence available suggests that withdrawal from the high level aquifer will have a negligible effect on the makai aquifer,” Thomas said, adding that Hawaii Island residents still need to monitor water use and be responsible with it.