An endangered native shrub found naturally on a plot of Navy land at the old Barbers Point Naval Air Station and nowhere else on the planet is at the center of a stalled land swap involving the Navy, state and U.S. Fish and Wildlife Service.

The population of Chamaesyce skottsbergii var. kalaeloana, otherwise known as the Ewa Plains akoko, dwindled from about 5,000 plants in 1979 to just over 630 last year, according to the service.

"If something isn’t done to conserve this plant, then it’s going to go extinct," said Aaron Nadig, a Fish and Wildlife biologist.

What should be done — and by whom — appears to be the million-dollar question in a time of ever-tightening budgets.

The Hawaii Community Development Authority, which is responsible for redeveloping the shuttered Navy base, said about 250 acres on three parcels, including the one that’s home to the akoko, were offered to it after the Fish and Wildlife Service and state Department of Land and Natural Resources turned the land down.

The akoko occupies 150 to 160 acres at what used to be the Navy’s northern trap and skeet range.

In 2011, the HCDA, a state agency, proposed an ambitious solar energy farm for that parcel, as well as on 80 acres of the adjoining southern trap and skeet range. No akoko has been identified on the southern parcel, officials said.

That later became a plan for 5 to 10 megawatts of photovoltaics on the northern site and 5 megawatts on the southern parcel, said Anthony Ching, HCDA’s executive director.

Ching said prospective solar companies could work around the akoko. But in addition to a Fish and Wildlife Service recommendation that 99 acres of the northern site be set aside for an akoko preserve, the service said HCDA would have to be responsible for the ongoing preservation of the plant, Ching said.

Developing a conservation management plan, putting in fencing and a firebreak road, doing clearing work, and hiring people to maintain the site and the akoko could cost hundreds of thousands of dollars in short- and long-term costs, Ching said.

"Let’s call it a million-dollar commitment," he said.

Ching said Fish and Wildlife is "trying to establish an unfunded mandate (for HCDA) for a situation for which they themselves chose not to take responsibility."

He noted that an earlier proposal had HCDA setting aside 50 acres for akoko on the northern site. The Fish and Wildlife recommendation now is for 99 acres.

Both the northern and southern trap and skeet ranges were designated as "critical habitat" for the akoko, officials said.

"It (the akoko preservation) is a worthy effort. It’s the law. We should protect our endangered species. I have no problem with that," Ching said. "But it can’t be unreasonable. You can’t expect to create an unfunded mandate and expect and then ask for the world and then seemingly create challenges for that to happen."

A photovoltaic field on the northern site alone could bring in a "couple hundred thousand" dollars in rent annually, but Ching said the costs and responsibility for the akoko make the plan — as well as HCDA taking the three sites from the Navy at all — unattractive.

Ching said he wasn’t sure that the return on 50 acres for solar production on the northern site would justify a $1 million investment to take on responsibility for the akoko.

Given the potential costs, the solar plan on the northern and southern sites "is a decision for (the HCDA board) to consider, but my recommendation would not be likely to support that," Ching said.

"It doesn’t look good, but I’m still seeking to confirm all the particulars," he said.

Ching said HCDA will pursue a 5-megawatt solar farm on a separate land parcel it already received at Kalaeloa.

The Fish and Wildlife Service, meanwhile, disputes Ching’s contention that it didn’t want the three parcels of land, which include the two former skeet ranges and Ordy Pond, a nearby 10,000-year-old water-filled karst sinkhole.

"That wasn’t the situation," said Nadig, the Fish and Wildlife biologist. "The situation was that the Fish and Wildlife Service did want it, and they’ve actively pursued trying to include that as part of their conservation lands out there at Barbers Point."

But Fish and Wildlife didn’t have the ability to take the land because of lead contaminants at the old skeet ranges and military dumping in and around Ordy Pond, Nadig maintained.

"Without the Navy maintaining liability for those contaminants, then Fish and Wildlife does not have the ability to acquire those lands," he said.

The Navy "essentially refused to maintain that (responsibility) and said, ‘You need to take it as is,’" Nadig said.

As for the "unfunded mandate" claim that Ching makes against Fish and Wildlife, Nadig said, "We did not impose anything on HCDA, or we’re not telling HCDA they have to do anything."

Fish and Wildlife has been in contact from the beginning with HCDA and the solar companies that wanted to operate on the land.

"We’re at a point where we need to protect a large chunk of this land for the species, because it only exists there," Nadig said. "We were very upfront from the beginning — if they can’t do that, then maybe they shouldn’t look to doing it, and look elsewhere."

A 2011 Navy environmental assessment for the disposal of surplus property at the old Barbers Point said the northern trap and skeet range was in active use in 1950 and abandoned sometime before the early 1960s.

A lead and arsenic removal project was conducted in 2003 and 2004, with about 52,000 cubic yards of material "stabilized" using "triple super phosphate" and 42,000 cubic yards processed through mechanical screens.

The assessment said soil with akoko clusters was manually excavated to preserve the plants.

The Navy said the actions cleaned the site to U.S. Environmental Protection Agency "unrestricted use" levels.

Nadig said there is still the potential of finding contaminants.

"You can still find lead out there," he said.

Bill Doughty, a spokesman for Navy Region Hawaii, said a "finding of no significant impact" for the reuse of Barbers Point land requires that the Navy have an akoko conservation and management plan in place before it transfers the land.

A nearly $1 million Navy cleanup of Ordy Pond was mounted earlier this year.

The endangered native plant that’s creating all of the fuss is an unassuming shrub that grows 2 to 4 feet tall with roundish leaves that are shed in the summer. It has very small flowers and fruit, and milky sap.

A plant relative that grows on Molokai is genetically different, officials said.

Ewa Plains akoko thrived on the coral shelf substrate that underlies the area and which is full of karst sinkholes and underground water­ways as a result of erosion.

"The history of this plant is that it was probably found across the whole Ewa Plain in that coral reef area," said Vickie Caraway, a Fish and Wildlife botanist.

Development, including the Barbers Point Deep Draft Harbor, took its toll on the population, she said.

From 2003 to 2008, the Navy created an akoko nursery on the northern trap and skeet range lot and that resulted in an increase in the plant population, Caraway said.

"But after the management ended, the population started to go back down, so it was an indication there needs to be long-term management," she said.

Right now, there are some volunteer efforts, "but it’s going to take more than that," Caraway said.

Fish and Wildlife efforts to grow some of the plants elsewhere failed.

In the meantime, the Navy is still responsible for the northern trap and skeet land — and the dwindling akoko, officials said.

Doughty said it remains the Navy’s goal to convey the property to the HCDA.

But if HCDA doesn’t want it, the service will "identify other potential property recipients."

The Navy will continue to facilitate akoko conservation and management plan negotiations between HCDA, the state DLNR and the Fish and Wildlife Service "to reach a consensus on the acreage needed for the protection and conservation of the endangered akoko plant," Doughty said.