Efforts to keep Waikiki Beach from washing away have a long history, dating back to the late 1920s.

A remnant of that history, a crumbling 89-year-old concrete barrier known as the Royal Hawaiian Groin, is holding the beach together — but probably not for long.

The groin, located between the Royal Hawaiian Hotel and the Sheraton Waikiki, “could fail at any time,” according to an environmental assessment produced for the state Department of Land and Natural Resources (DLNR).

Failure could be disastrous. The groin prevents sand from migrating westward, allowing it to accumulate to form the world-famous beach that drives a significant part of Hawaii’s tourist economy.

There’s little doubt the groin needs to be replaced. At the moment, it is being propped up with sandbags and crossed fingers. What to replace it with is a more complicated question.

The preferred alternative among four developed by Sea Engineering Inc. for DLNR calls for a much larger structure, built with boulders as large as 4,500 pounds, shaped like a T and extending 180 feet into the ocean from the seawall in front of the Sheraton Waikiki.

It would be a sight to see. The current groin, a slender finger curving gently eastward, falls apart and disappears under the water after the first 150 feet of its original 370-foot length.

Beauty is in the eye of the beholder, of course, and anyone who wants to see what the proposed groin would look like need not imagine it: Nine similar groins, also designed by Sea Engineering, were built at Iroquois Point and have held that beach together nicely.

The environmental assessment concluded that the proposed T-shaped groin would not have a significant impact on the area: “The project will not significantly alter or affect presently on-going sand transport and shoreline processes, wave-driven currents, circulation patterns, overall water quality, or offshore wave breaking.”

Critics of the plan dispute this conclusion. They fear the proposed groin, which supposedly would be more effective than an antiquated concrete wall, could permanently change the characteristics of the beach and nearshore ocean, negatively affecting some of the most popular activities in Waikiki — surfing, fishing, snorkeling and swimming.

Surfers fear that the new groin could change the characteristics of wave breaks, which are affected by the profile of the ocean floor.

At a public hearing on the proposal, Robert Peters, part of a 1969 effort by Save Our Surf to stop a multigroin project in Waikiki, said, “Not once did you mention anything about the effect on surfing. This is the beauty of Waikiki. It’s not the sand and beach for tourists.”

In written testimony, George Downing, a spokesman for Save Our Surf, warned that the structure not only could detrimentally affect popular surf breaks, but endanger beachgoers who might get knocked against the rocks, and create an attractive nuisance for unwary people climbing or walking on the groin and its slippery boulders. The latter is a reasonable concern, when one considers the foot traffic on the Kapahulu Groin a short distance away.

And while Sea Engineering says the structure would increase marine life living in the crevices between its rocks, as happened at Iroquois Point, opponents say yes, it would — with dangerous eels.

Nonetheless, there seems to be broad agreement that something needs to be done. And with all due respect to surfers, the beauty of Waikiki lies not only with them, but with the sand and beach and tourists — and all of the other myriad attractions that draw locals and visitors alike.

The primary purpose of the new groin will be to provide effective protection of Waikiki Beach. Yes, the Board of Land and Natural Resources should consider the best option to preserve the beach and nearshore ocean as it is. That may mean replacing the old groin with a similar structure; while it may not be as effective as the preferred one, it would have a smaller footprint and not be such an attractive nuisance for inexperienced beachgoers.

Nonetheless, even the 180-foot T-shaped groin would be better than what’s there now. The important thing is to get it done.