A nearly $10 million federal grant to the state will restore habitat from “summit-to-sea,” with the goal of saving West Maui reefs.

Among them is Olawalu Reef on Maui’s southwestern shore, which is often referred to as the “mother reef.” The 1,000-acre coral reef is a designated Mission Blue Hope Spot, and home to a diverse array of unique coral species and the nation’s largest known population of manta rays.

But the reef is in peril, according to conservationists, due to many threats such as rising sea temperatures, pollutants, wildfires and soil sediments carried to it from nearby streams.

The National Oceanic and Atmospheric Ad­ministration recently awarded the state the Transformational Habitat Restoration and Coastal Resilience Grant to support a comprehensive, mauka-to-makai approach to restoring West Maui reefs.

The “summit-to-sea” project, awarded to the state Department of Land and Natural Resources as the project lead, will take several actions, including:

>> Work to address major sources of erosion, including an evaluation of whether a sediment capture basin is feasible.

>> Reforestation projects to stabilize soils.

>> New fire breaks to reduce the frequency and intensity of wildfires, which result in habitat loss and erosion.

>> Installation of fencing to control hoofed animals such as pigs, goats and particularly axis deer that denude the habitat, resulting in erosion.

>> Riparian habitat restoration along rivers, streams and other bodies of water.

>> The addition of two 40,000-gallon dip tanks for wildland firefighting.

The DLNR Division of Forestry and Wildlife will lead the three-year project in collaboration with the state Division of Aquatic Resources and numerous conservation groups such as The Nature Conservancy.

Scott Fretz, DOFAW Maui branch manager, said to protect the reef, conservationists need to look upslope, where erosion results in soil traveling down streams to the coral reef in oceans, smothering them.

These sediments stifle live corals as well as prevent new coral from growing, according to The Nature Conservancy — and this makes the reef even more vulnerable to other stressors such as algal growth and disease.

“Sedimentation is one of the biggest threats, and that is all land-based,” Fretz said. “The only way you’re going to solve that is working mauna to makai, working with the land managers all the way to the summit and then working with marine partners.”

The project area covered by the grant stretches from Olowalu to Ukumehame.

Some of the challenges, said Fretz, included bringing a hodgepodge of lands, some of which was unmanaged, under state jurisdiction.

“This is an area where we have effective land management in the upper elevations of state forest reserves,” he said. “However, one of the real challenges resource managers have faced for many years in the project area is that lower-­elevation lands have a number of issues that lead to erosion and sedimentation that impacts the coral reef ecosystem.”

Wildfires are a major cause of erosion and sediment ending up on the reef.

The “grass-fire” cycle is a vicious cycle, in which fires travel up hills of invasive grasses, destroying Hawaii’s native forests.

The flammable, invasive grasses take over, serving as fuel for the next fire — and the destruction continues farther upland, destroying more native habitat in the forest. After fire travels through, many areas are left scarred and barren.

When heavy rain falls, sand descends down the mountains to the reefs in the ocean.

Fretz said the state and partners have been working to stop this grass-fire cycle and erosion well before the Lahaina fires occurred in August 2023.

“Fires have been a problem in this area for a long time,” he said. “Not just this area, but plenty of areas around the state where fires are frequent, and it causes erosion that damages coral reefs.”

With part of the grant, The Nature Conservancy is doing preliminary work to see whether a small retention basin at Manawaipueo Gulch would help keep sediment from reaching the ocean.

TNC’s Tamara Farns­worth said she hopes to one day see clear streams running again.

“My dream is to see healthy fisheries developing, to see brighter and more diverse corals on the reef,” said Farnsworth in a news release. “The really big dream is to see limu return to these shores. I think that’s a wonderful vision for us to work toward, is very abundant limu here back in the ocean and on the shores.”

Olawalu reef is also a source of coral larvae, or coral offspring, that populate the reefs of Molokai and Lanai, according to DOFAW Maui District Aquatic Biologist Russell Sparks.

“It’s remnant, nearshore coastal reef that’s still fairly healthy,” Sparks said. “Most reef flats around Maui, on either side of that area, have more or less died because of sedimentation. A lot of it occurred over 100 years or more with the plantation era, but now when you find a reef system that’s intact and nearshore, it’s one we want to help protect in the future.”

The grant was funded through President Joe Biden’s Bipartisan Infrastructure Law and Inflation Reduction Act.