HONOKOHAU — At what is now Kaloko-Honokohau National Historical Park, the water flows beneath the ground and out to the bay, mixing with the saltwater to create an environment perfect for the ‘ama‘ama, or mullet, whose predators can’t tolerate the lower salinity.
Ancient Hawaiians took advantage of the fish’s movements by constructing a massive wall to create the Kaloko Fishpond.
By using channels and gates in the wall to control the fish’s entrances and exits, they were able to create a sustainable source of food.
Today, the mullet, awa and papio still swim back and forth through those channels in the ancient wall, currently being reconstructed by park masons. Nearby, seemingly lifeless anchialine pools teem with opae ula, the tiny red shrimp that make their homes in the brackish pools.
But park rangers fear increased use of the island’s limited freshwater resources combined with decreased rainfall and rising sea levels could upset the delicate ecosystem.
As a result, they’re asking the state Commission on Water Resource Management to step in and designate the Keauhou Aquifer, which covers a vast region from Makalawena Beach to north of Kealakekua Bay, a water management area.
Designation would give the National Park Service a chance to weigh in on the future of water withdrawals in the area.
That would include any applications by developers to build new wells mauka of the park’s boundary.
Not everyone is on board with the proposal though.
Opponents say the park service hasn’t shown any evidence there’s a problem. Commission staff already filed a report recommending against the designation, instead offering several alternative recommendations.
A hearing for the proposal is scheduled for 9:30 a.m. Tuesday at the West Hawaii Civic Center.
The park also is home to two endangered species of water bird — the Hawaiian coot and the Hawaiian stilt.
The adult birds are able to tolerate a wide range of freshwater and saltwater, but the young, who aren’t able to fly, need a local source of freshwater.
“We want to be able to have the whole life cycle of the bird and not just the adults,” said Jeff Zimpfer, an environmental protection specialist at the park. “So, we need freshwater so we can have new coots and stilts coming along.”
When the park was created in 1962, there were very few wells in the area, Zimpfer said. But Kona’s development led to the installation of more and more wells.
State law allows the commission to designate a water management area when it finds water resources are threatened by existing or proposed wells and other diversions of ground and surface waters.
Before a water system can be designated a state management area though, the commission needs to consider several factors.
That includes whether increased water use could cause the rate of water withdrawal to reach 90 percent of the area’s sustainable yield — the maximum rate at which water can be withdrawn from its source without reducing quality.
The Keauhou Aquifer’s sustainable yield was determined to be about 38 million gallons per day. Current water use in the aquifer system is about 14.55 million gallons per day, roughly 38 percent of the sustainable yield, according to the Park Service.
Opponents of the proposed water management area designation say that’s not nearly high enough to justify the park service’s request.
“Nobody has provided any scientific information that says there is a problem,” said Peter Young, a former state Department of Land and Natural Resources director and former chairman of the Commission on Water Resource Management.
While Zimpfer acknowledges the pump rate isn’t hitting the 90 percent threshold, he said the sustainable yield model isn’t a perfect one because wells aren’t evenly dispersed across the aquifer. That means there’s a disproportionate effect on parts of the aquifer.
If the commission designates the aquifer a water management area, anybody wanting to withdraw or divert use would need to get a permit, according to the Water Code. Permits wouldn’t be required for domestic consumption by individual users nor for a catchment system.
Existing uses would be able to continue until the commission acts on operators’ permits.
Young said denying the designation doesn’t mean the question of water usage is a nonissue.
What should happen, he said, is that stakeholders continue to watch the issue, track changes and share findings in the event circumstances change.
Email Cameron Miculka at cmiculka@westhawaiitoday.com.
