For nine decades, the Royal Hawaiian groin has shielded Waikiki structures and the famous strip of beach that has attracted countless visitors. These days, though, any passerby can see that the thin and frail concrete- block breakwater jutting into the ocean near the Royal Hawaiian and Sheraton Waikiki hotels is poised to collapse.

Its toppling could destabilize the area and essentially erase a 1,730-foot stretch of sandy shoreline that’s valuable to the state’s tourism-focused economy. What should be equally alarming is that in the absence of a strong check against erosion and other emerging climate change threats, Waikiki is increasingly vulnerable to damage tied to high waves and storms.

When an environmental assessment was published in early 2016, officials weighed various fixes — and it was widely assumed that a new groin project would be tapped as high-priority, with construction wrapped up by now. That has not happened, unfortunately. And apparently due to the ongoing delay, state funding set aside for the project that lapses in June did not get re-appropriated during this year’s legislative session.

Given the design, permitting and funding hurdles ahead, it now appears that construction will start no sooner than fall 2020. That’s a precariously long time to wait, considering that experts have been saying for for well over a year that collapse could occur any day now. If there’s a way to fast-track the project, it should be seized.

The state Department of Land and Natural Resources makes a persuasive case for a 180-foot T-head rock-wall groin, which engineers say would improve protection against summer swells and expected sea-level rise. But stalling progress is the state Board of Land and Natural Resources’ call for a second design review, which is still in progress.

In March 2017, BLNR member Keone Dow­ning opposed the T-head design along with fellow Save Our Surf members, and pushed for the additional review to satisfy concerns that the proposed structure — about 10 times larger than the aging groin — might change wave quality that surfers now enjoy or attract predatory eels.

While the T-head structure would change the ocean floor footprint from about 550 square feet to more than 5,000 square feet, the proposed sloping rock rubble mound would provide good wave energy dissipation and minimal wave reflection — little impact on shore breaks. That’s according to Sea Engineering Inc., the lead design firm on the groin project and on the state’s 2012 Waikiki beach nourishment project. The firm has put in place nine similar groins at Iroquois Point, which are holding that beach together nicely.

Built with boulders as hefty as 4,500 pounds, a rubble mound’s crevices do invite more marine life, including eels. But contending with that is preferable to the painful financial bite that will result from continuing to delay replacement of the deteriorated groin.

Within the past few years, the project’s price tag has spiked. Due in part to a construction boom linked to infrastructure grades needed to fend off the now-surfacing effects of global warming, the project, which was initially tagged at $1.5 million, is now estimated at $2.5 million. The Waikiki Beach Special District Improvement Association, meanwhile, has pledged to pick up half of the cost, and is standing by.

What’s more worrisome, of course, is that further deterioration of Waikiki Beach could turn off tourists, touching off drops in the annual tally of billions of dollars in visitor spending.

The primary purpose of the new groin is to provide effective protection of the coast area in coming decades. Yes, the BLNR should aim to preserve the beach and nearshore ocean as it is. But the apparent search for a perfect fix is leaving us with rising levels of risk.

For now, the important thing is to put in place something better than what’s barely there.