It was no fluke this month when the voyaging canoe Hokulea, wrapping up six years of intense sailing to rally for healthier oceans, docked in Hawaii’s most notoriously polluted waterway.

Cleaning the Ala Wai Canal and the streams that feed it remains one of the state’s most daunting environmental challenges. The Ala Wai runs across Hawaii’s most densely populated watershed. Any fish caught from its murky waters aren’t safe to eat. Any paddlers better pray they don’t fall in.

“When we succeed at cleaning the Ala Wai, what we can tell the young people and to the world (is) we can do anything,” Polynesian Voyaging Society President Nainoa Thompson told an audience at the Hawaii Convention Center shortly after crews moored the Hokulea there.

“That’s what’s at stake.”

Now, a local coalition has set a bold goal to make the Ala Wai’s waters fishable and swimmable again within seven years. They also aim to restore what ecological balance they can to the surrounding 19-square-mile Ala Wai watershed.

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Whether this broad effort led by the nonprofit Hawaii Exemplary State Foundation succeeds will largely depend on the help and buy-in of local schools and community groups, organizers say.

But the restoration plan comes as the U.S. Army Corps of Engineers advances its own congressionally approved infrastructure project for the Ala Wai watershed: A $345 million flood mitigation effort to protect Waikiki and the crowded neighborhoods around the canal from severe damage in a major storm.

Previously, habitat restoration was a chief component of the corps’ project but the agency later scrapped it. Now, its sole focus is to control fast-moving flood waters.

Restoration advocates say that limited scope is short-sighted. They worry some of the flood control infrastructure poised to take shape across the watershed might be at odds with their separate efforts and temper the community support they need.

“If the Army Corps plan was allowed to go forward, it would mean a major rethinking of what we had planned for the restoration project,” said Kenneth Kaneshiro, the foundation’s president. “It would sort of disrupt our plan.”

On the other hand, if the corps were to rethink the plan and include restoration it might be able to reduce the impacts, particularly the basins and walls that have caused so much recent controversy, Kaneshiro and others say.

Restoration and flood control, they argue, should go hand-in-hand.

“They went ahead with half a project,” said Karen Ah Mai, executive director for the nonprofit Ala Wai Watershed Association. “Half the toolbox is missing.”

Local corps officials say they might still pursue smaller, isolated restoration efforts within the watershed. However, the flood project’s scope is locked in based on what Congress approved. There’s no going back, they say.

A New Plan To Restore From Mountains To Ocean

The Exemplary State Foundation and its partners hope to launch multiple restorative projects in the area, from the upland forests to the ocean, that would work together. They aim to raise between $150 million and $250 million from federal agencies to make that happen, Kaneshiro said.

“We’re taking the whole ahupuaa watershed approach,” he said, referring to the traditional Hawaiian division of land from mountain to coast.

It’s an ambitious goal, he acknowledged, but with the community’s support “it’s potentially doable.”

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To cleanse the century-old 1.5-mile canal, the partnership will test innovative techniques that have succeeded elsewhere but haven’t been used in the Ala Wai. That includes introducing cages of native Hawaiian oysters to filter the water of heavy metals and harmful chemicals, plus dropping scores of softball-sized mud balls filled with special bacteria in the canal to digest the organic sludge that’s settled there.

In large enough numbers, the organizers of those separate initiatives say, those resources could make a sizable dent in the Ala Wai’s pollution problems.

The first several hundred native oysters are poised to enter the canal in the next two weeks, said Rhiannon Tereari’i Chandler-’Iao, executive director of the nonprofit Waterkeepers Hawaiian Islands. The project mirrors similar efforts on the U.S. East Coast, such as the Billion Oyster Project, which aims to help clean New York Harbor.

The mud ball, or “Genki-ball” initiative, meanwhile, is similar to a proposal suggested two years ago by Punahou School students for the University of Hawaii’s Ala Wai Challenge. Genki Ala Wai, the group that aims to test the balls in the canal over the next two years, plans to meet with state health officials this week to try and secure the necessary permits.

Researchers from UH’s Gates Coral Lab also plan to monitor the coral near where the canal empties into the ocean, monitoring for any improvements there.

But most of the issues at odds with the corps project originate upstream, particularly where restoration partners aim to eradicate the invasive albizia trees that blanket the Manoa Valley.

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The fast-growing alien trees were planted across Hawaii about a century ago around the same time developers built the Ala Wai canal to drain the Waikiki wetlands for building. Since then, the trees have proliferated to infest about 20,000 acres across Oahu, local experts say.

Albizia branches fall easily, and they’ve wreaked havoc in recent storms. In 2004, they comprised much of the debris that clogged the Manoa Stream during heavy rains and led to $85 million in damage.

They’re also costly to remove at about $15,000 per tree, estimated Kaneshiro, who directs the Center for Conservation Research and Training at UH Manoa.

The Exemplary State Foundation looks to replace the Manoa albizia with kukui nut trees, which aren’t native to Hawaii either but would be far more compatible with the local ecology, Kaneshiro said. The goal is to burn the discarded albizia and then the steady supply of kukui nuts as an alternative energy source that could power a micro-grid, he added.

Removing a chief source of storm debris in Manoa as part of habitat restoration could also reduce the corps’ need for so many basins to catch that debris, Kaneshiro and Ah Mai said.

“The main problem is the Army Corps’ plan is strictly an engineering solution,” Kaneshiro said.

Further down the watershed, projects to replace much of the impenetrable concrete surface that coats Makiki, McCully-Moiliili and other urban strongholds with permeable ground to absorb rainwater would help alleviate the need for flood engineering too, he said.

However, Jeff Herzog, the corps’ project manager for Ala Wai flood control, said even if there wasn’t any storm debris the basins would still be needed to hold back fast-rushing flood waters.

Corps Could Pursue Smaller Habitat Projects

At a recent Ala Wai restoration summit — the same meeting Thompson addressed — many participants were eager to strategize how they might sway the corps to alter its project rather than further discuss their own restoration plans.

Watershed restoration was part of the corps’ original scope in 2001 but it was cut in 2012 because the agency didn’t find sufficient benefits on a national level for the costs involved, Herzog said Thursday.

“We weren’t able to justify it on a system-wide approach,” he said.

The corps’ environmental impact statement from 2017 states: “An analysis of biological resource significance determined that the resources within the Ala Wai Watershed are significant at a regional level (versus at a national level). As such, ecosystem restoration was removed from the scope of the study.”

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Water quality was also removed as an objective from the Army Corps’ study, according to the EIS.

“We sat through years of those discussions and it suddenly got chopped off,” recalled Ah Mai of the Ala Wai Watershed Association. “They proceeded to try to get their structural improvements … but there’s a whole half of the equation missing or more.”

Herzog said he wasn’t sure whether the corps’ project might conflict with any of the watershed-wide restoration efforts “just because my scope has been flood risk mitigation.”

The flood-control-only focus doesn’t preclude the corps from pursuing smaller, separate restoration efforts as “a parallel effort to the construction project that’s already going on,” Herzog said. The corps has committed to the Department of Land and Natural Resources that it would look at those projects, he added.

They might include converting part of the Ala Wai Golf Course into loi wetlands, or restoring concrete channels in Makiki to natural stream beds, Herzog said.

He and local corps officials plan to hold a June 17 meeting at the Honolulu Country Club with local nonprofit groups, academics and industry professionals to discuss how they might improve the design, reducing community impacts and concerns.

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“We are looking at engineering in nature where we can,” Herzog said.

However, despite any fine-tuning “we’re locked into these features,” he added.

For some in the watershed, restoring the natural system should be the first step toward flood protection.

“It was the genius of our ancestors who engineered the perfect water system — they called it the ahupuaa,” Imaikalani Winchester, a teacher at the Makiki-based Halau Ku Mana Public Charter School, said at a March 19 town hall on the project in Manoa.

“I can save everybody here millions and millions of dollars. All we need to do is get our community, our schools, our keiki, our generations to buy into taking care of what we have. If we protect our sheds, if we protect our streams … we can be prepared.”