State wildlife officials are trying to preserve an area on Oahu critical to groundwater protection where four native plant species are making their last stand.
Officials said in Kaluanui in the northern Koolau range, each of the four native species has fewer than 51 plants.
"Many of these native species are only found in the Kaluanui area and are perilously close to extinction from the impacts of invasive plants and animals," said William Aila Jr., chairman of the state Department of Land and Natural Resources.
A public hearing to create the proposed Kaluanui Natural Area Reserve is scheduled for 6 p.m. Wednesday at the Queen Liliuokalani Children’s Center in Hauula.
The state has proposed designating 376 acres in Kaluanui as the reserve.
Under the proposal, the administration of the land would be transferred from state parks to the Division of Forestry and Wildlife.
The proposal is also part of DLNR’s "The Rain Follows the Forest" initiative to increase groundwater protection.
If approved, Kaluanui would become the fourth natural area reserve on Oahu and the 21st statewide.
The four plants are among 29 endangered species mauka of Kaliuwaa Stream’s "Sacred" Falls, where the waters converge from three streams, including Kaluanui Stream.
The four plants, scattered in clusters in and around the proposed reserve, include the herb plant Pteris lydgatei, mint plant Phyllostegia hirsuta and bellflowers Cyanea purpurellifolia and Cyanea st.-johnii.
In addition to saving native species, the proposed reserve will improve protection of native forests and Hawaii’s watershed, and prevent erosion from muddying beaches and reefs.
Although natural area reserve rules allow hiking, the access trail from Punaluu is difficult, and state workers have used helicopters to work in the region, located between the 2,200- and 2,800-foot elevation.
"It’s really remote, inaccessible. … It’s not a hunting area," said Emma Yuen, an official with the reserve.
The reserve does not include the Sacred Falls area, and its trail remains closed.
State officials said Kaluanui Stream, which runs through the upper reaches of the reserve, is home to all five native oopu species, also known as goby fish.
Some $400,000 in state and federal grants has been authorized to develop fencing to keep out pigs and protect the watershed but still allow hikers access into the reserve.
Some $100,000 more is needed to complete the fencing, a reserve official said.
"The Natural Area Reserves System seeks to protect the best remaining samples of Hawaii’s unique ecosystems," Aila said.
