Hydrologists and consultants are making the case that water use in Kailua-Kona is not reducing or degrading the northern portion of the Keauhou aquifer.
A presentation by the experts was given Wednesday in Kailua Village at the behest of the Hawaii Leeward Planning Conference as the state eyes a petition to put the aquifer under the control of the state Commission on Water Resource Management.
Data collected since 2002 shows Ooma nearshore wells and others in the north portion of the aquifer haven’t increased in salinity, said Tom Nance, a hydrologist and water resource engineer.
“It hasn’t gotten saltier, and the lens has not gotten thinner according to data here,” said Nance, who compiled profiles of salinity at various depths.
Nance said he doesn’t believe any of the criteria for designation are close to being reached. However, other wells are in the works and should be closely monitored to make sure the basal lens is not impacted, he said. There will also likely come a point when water must be drawn from sources in South Kona for development in the north, Nance said.
Steve Dollar, an oceanographer and consultant, studied the effects of groundwater on fishponds and coastal areas of Kaloko-Honokohau National Historical Park over 12 years.
“For one reason or another, (Aimakapa) Pond is getting younger,” Dollar said. “Rather than nutrients decreasing and salinity increasing, it’s doing the opposite.”
Levels of silica, which are high in fresh water and low in ocean water, have varied but not decreased in the pond, indicating it is getting a healthy recharge of groundwater, Dollar said.
“There have been no negative impacts to the nutrient dynamics over the last 12 years,” Dollar said.
The findings are contained in a new report compiled for the Planning Conference. The study also contains research on anchialine pools by scientist Richard Brock and the influence of the tides on freshwater salinity by groundwater geologist Steve Bowles.
Scientists are still grappling with the dynamic of the aquifer, including the possibility that salinity measurements are affected by ocean water circulating under the island. They do not yet understand how waters in the mauka portion of the aquifer feed into the lower portion, or basal lens — or whether all the unused mauka groundwater reaches the lens or is diverted elsewhere.
The National Park Service petitioned last year to designate the aquifer a state water management area, citing concerns about its viability in the face of future pressures. The water is currently the responsibility of the Hawaii County Department of Water Supply.
Under the state designation, all water users expect individual domestic users and those on catchment systems will have to apply for a state permit for the water they are already using, said Roy Hardy, the state’s groundwater program manager, at a similar roundtable discussion earlier this month.
County officials have put up stiff resistance to the petition, worrying that the added layer of bureaucracy will hinder long-needed development projects. This campaign season, the designation has also become a political issue.
A long line of candidates, including those in the governor’s race, have opposed the move. Congresswoman Colleen Hanabusa, in a letter this month to National Park Service Director Jonathan Jarvis, said the petition appears to be based on an incomplete picture of the island’s hydrology and called for more study. Sen. Brian Schatz has said the move is an overreach by the federal government.
The aquifer runs from Makalawena to Kealakekua.
Tammy Duchesne, superintendent of Kaloko-Honokohau National Historical Park, said she is confident the commission will make the right decision.
Hardy said in an interview that the commission is in the process of gathering information as widely as it can in preparation for a decision in December on whether to pursue the designation.
The commission must examine not just the science, but future development plans, he said.
“Designation is appropriate when there is not enough water to go around,” Hardy told the audience of about 160. “When sufficient water is available, there are other tools to manage the resource.”
The commission will also visit wells in West Hawaii and take briefings in September and October, Hardy said.
“Dec. 10 starts the clock ticking,” Hardy said. “If the commission decides to continue, they have to make a (final) decision in 90 days.”
A public hearing will be held in Kona prior to any final decision, Hardy said.
The HLPC will hold another water roundtable Aug. 27 at King Kamehameha’s Kona Beach Hotel, the conference’s president Jacqui Hoover said. The National Park Service is expected to present information at that meeting.