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Places We Protect

Olowalu

Island of Maui

Landscape view of a large mountain range near the coast of the Hawaiian island of Maui.
West Maui Coral reefs diminish wave energy, protecting coastal communities like Olowalu from the power of the sea. © Lyle Krannichfeld

Uniting to protect one of Maui’s largest fringing reefs.

In 2017, West Maui's Olowalu reef was declared a Mission Blue Hope Spot—a place that is critical to the health of our oceans. Spanning the coast from Olowalu to Pāpalaua, the 939-acre reef boasts a stunning diversity of coral, harbors the largest known manta ray population in the United States and is a primary source of coral larvae for the reefs of Lāna'i, Moloka'i and West Maui.

Closeup of the ridges and grooves of a mushroom coral.
Mushroom Coral A stunning diversity of marine life attracts island residents and visitors from around the world to this Hope Spot. © TNC/Alana Yurkanin

This expansive ecological treasure is also critical to the health of the community and economy, reducing wave energy and moderating erosion and flooding along the coast, where it protects homes, a coastal highway that connects West Maui with other parts of the island, and two beach parks. Tens of thousands of Maui residents and visitors travel the highway each day, with many stopping to visit the area’s beaches to enjoy reef-based activities such as snorkeling, diving, and surfing.

In Hawaiian culture, coral has long been revered. The sacred creation chant Kumulipo teaches us that the coral polyp was the first organism to emerge from the deep darkness, the most ancient ancestor, the foundation for all other life. It also teaches us that life in the sea and life on land are inextricably linked, that what we do on land impacts our ancient sea-dwelling ancestors. That link is clearly visible in Hawai‘i’s coastal waters and on the coral reefs they harbor. Olowalu is no exception. 

Hope for a Hope Spot

The reef at Olowalu is regularly inundated with soil sediments carried to the ocean from nearby streams. These sediments smother live corals and prevent new corals from growing, making the reef more vulnerable to other stressors such as algal growth, disease, and marine heat waves. In fact, surveys following a statewide bleaching event in 2015 documented up to a 45% loss of live coral on the Olowalu reef.

Fortunately, landowners, land managers, and other groups with interests from mauka to makai (uplands to the sea) have joined forces to protect this irreplaceable natural wonder by reducing stressors and building reef resilience.

Water Detectives

A group of citizen scientists, known as Hui O Ka Wai Ola, collect coastal water quality data at Olowalu and more than 30 other sites along West Maui’s leeward coast. Their efforts measure a dozen components of water quality, including levels of sediments and nutrients, and fill information gaps, complementing data collected by the Hawai‘i Department of Health. Three organizations—TNC, the Maui Nui Marine Resource Council, and West Maui Ridge to Reef Initiative—partnered to launch the group and support its efforts through ongoing coordination and data analysis. To view findings from the sites they monitor, visit https://www.huiokawaiola.com/

Aerial image of a coastline with brown water.
FROM MAUKA TO MAKAI Sediment-laden waters flowing from degraded upland areas after heavy storms inundate the reef. © Jon Brito/ DLNR DOFAW

Reducing Sediments from Upland Areas to Increase Reef Resilience

Minimizing sediments in coastal waters is a vital step toward building reef resilience. The Nature Conservancy (TNC) is working with the National Oceanic and Atmospheric Administration (NOAA), the Hawai‘i Divisions of Aquatic Resources (DAR) and Forestry and Wildlife (DOFAW), county, state, and private landowners, and the broader community to identify and implement actions to reduce harmful sediments on the reef. These efforts—informed by our ongoing scientific research in the watershed and in coastal waters—are focused on reducing sediment flows through effective watershed management, including improved fire and ungulate control and the installation and maintenance of sediment capture and retention systems in Pāpalaua and Manawaipueo gulches. 

Ocean floodwaters encroach on a road that a tractor-trailer truck is driving down.
RISING SEAS The coastal highway running through Olowalu—and connecting west Maui with the rest of the island—experiences regular flooding. © Michelle Griffoul

Promoting Nature-Based Solutions to Build Coastal and Reef Resilience

Coastal erosion driven by sea-level rise and storm surge is prevalent and increasing along the West Maui coast, where it accelerates the degradation of habitat and destruction of coastal infrastructure. Olowalu has been particularly hard hit, with the coastal Honoapiʻilani Highway experiencing chronic flooding. Though seawalls were installed to mitigate the flooding, this type of shoreline hardening can impede beach migration and other natural ecological processes and exacerbate erosion and beach loss.

To address the chronic flooding and erosion, the Hawai‘i Department of Transportation is preparing to move six miles of the highway. With the highway expected to move inland, Hawaiʻi has a unique opportunity to restore the area’s natural features, including beaches, dunes, and wetlands, to recover the protective benefits of a living shoreline and allow for natural ecological processes such as seasonal beach migration. Restoring this natural infrastructure is a cost-effective alternative to investments in grey infrastructure to protect against the impacts of sea level rise, flooding, fire and sedimentation and can help mitigate the environmental impacts of the highway relocation.

a group of people gather around a table examining various maps on it.
PLANNING WORKSHOP Community members share knowledge and perspectives to enhance coastal planning processes. © TNC

Together, We Find a Way

Collaborative planning helps to avoid missteps and leads to better outcomes. To inform solutions for building resilience along the Olowalu coast, TNC partnered with Kipuka Olowalu and the Coral Reef Alliance to engage the community, landowners, and resource managers in creating a shared understanding of the cultural, historical, and ecological resources of the area and the opportunities for building resilience.

Through a series of conversations, interviews and small gatherings, the group developed an overview of the area that includes a status report on the health of the watershed and identifies key cultural and environmental concerns and priorities. The collaborative endeavor encouraged candid discussion among participants and helped to build trust between those with deep historical connections to Olowalu’s lands and waters and those with the tools and capacity to improve management.

Continuing conversations will help to ensure that the community voice is reflected in the various coastal planning processes and help to find ways to build resilience for the Maui community and for the reef.

We Are Our Island’s Keepers

Learn more about the efforts at Olowalu and how you can help.

Learn More
Closeup of bleached coral.
WARMING OCEAN WATERS A 2015 marine heatwave resulted in significant coral bleaching at Olowalu. © TNC/Alana Yurkanin

Investing in New Tools and Strategies to Protect Hawaiʻi’s Hope Spot

Because the Olowalu reef is a primary source of coral larvae for the reefs of Lāna‘i, Moloka‘i and West Maui, it is especially vital to build its long-term resilience to climate change. Reducing sediments and other local stressors on the reef is an essential first step, but it is not enough. Building resilience to global stressors such as marine heatwaves is also essential. Coral restoration has been helping to regenerate damaged reefs in other parts of the world for more than two decades and after multiple bleaching events in the last decade, it has become clear that restoration must be part of our reef management toolkit, as well.

TNC is working with partners to accelerate its use in Hawaiʻi by building the skills, knowledge and expertise necessary to collect, propagate and reattach coral fragments on reefs. Our work with government and community partners will determine which restoration methods work best for Hawaiʻi’s coral reefs. Learn about this vital work. Our partnerships with scientists at Stanford University and Woods Hole Oceanographic Institution will identify the most thermally tolerant corals and will model future ocean temperatures in the Olowalu area, respectfully, to ensure we restore coral reefs with the potential to withstand warming ocean temperatures in the locations where they are most likely to thrive. By working together to identify and inform solutions that address local and global stressors from mauka to makai, we can restore the health of this Hope Spot to help it withstand the increasing impacts of our changing climate.

Learn more about our tools and science, partnerships to restore makai areas and efforts to strengthen conservation management and leadership, so Hawaiʻi’s reefs can support healthy fisheries and prosperous communities long into the future.