Places We Protect


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.

Hawai'i’s reefs are a cultural treasure and part of our most ancient history. The Kumulipo is the Hawaiian creation chant that explains how life began in the islands. It tells us that the Ko’a, or coral polyp, was the first organism created, followed by seastars, cucumbers and urchins. The Kumulipo also teaches us that life in the sea and life on land are inexorably linked, that what we do on land impacts our ancient sea-dwelling ancestors. One place where that connection is clearly visible is at Olowalu on West Maui’s leeward coast.

In 2017, the 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

The Olowalu reef is also immensely important to West Maui’s community and economy. This valuable and expansive reef reduces wave energy reaching the shoreline, moderating flooding along the coast and protecting the Olowalu community and the only major road connecting West Maui with the rest of the island. The reef also protects two beach parks used by tens of thousands of residents and tourists each year and is an important area for nature-based recreational activities, including snorkeling, diving, surfing and paddling.

But the Olowalu reef is threatened by global and local stressors. Surveys following the 2015 statewide bleaching event documented up to a 45% coral loss on the reef, and it is under constant pressure from sediments that are carried to the ocean from nearby streams and culverts and churned up during wave events. These sediments settle on the reef, where they smother live corals and prevent new corals from growing. Herbivorous fish are critical to maintaining reef health but are in decline at Olowalu, leading to a proliferation of algae that overgrow and smother the reef.

Reducing Sediments from Upland Areas to Increase 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 sediments on the reef. These efforts—informed by our ongoing scientific research in the watershed and coastal waters—are focused on reducing sediment flows through effective watershed management, including improved fire and ungulate control and the installation and maintenance of detention basins in Olowalu and Manawaipueo gulches. Minimizing sediments in coastal waters is a vital step toward building reef resilience.

Aerial view of heavy sediment in ocean waters along the coast of Hawaii.
FROM MAUKA TO MAKAI Sediment-laden waters flowing from degraded upland areas after heavy storms inundate the reef. © Courtesy TNC Hawaii

Introducing Nature-Based Solutions to Increase 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 Honoapiʻilani Highway experiencing regular flooding. Though seawalls were installed to mitigate the flooding, this type of shoreline hardening can also impede natural ecological processes and exacerbate erosion and beach loss.

Learn more about this and other ways you can help.

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

Fortunately, the Hawai’i Department of Transportation is preparing to move six miles of road inshore to reduce chronic flooding and erosion. This effort provides a unique opportunity to incorporate nature-based solutions—specifically, restoration of the area’s natural features, including reefs, beaches, dunes and wetlands—to mitigate the impacts of sea-level rise. This “natural infrastructure" can be a more cost-effective alternative to gray infrastructure, building coastal resilience by maintaining and expanding natural, ecological systems and processes such as seasonal beach migration. TNC is currently working with local partners to engage the community in a planning process to identify effective nature-based solutions in concert with the road realignment and other coastal planning processes in the region. Together, our goal is to reduce coastal erosion and flooding while demonstrating the power and value of nature-based solutions with and for the Maui community.

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 Maui Nui’s Mother Reef

Because Olowalu is a primary source of coral larvae for other reefs in the area, it is especially vital to build its long-term resilience to climate change. While reducing pressures on the reef is an essential first step, TNC also supports active coral restoration of the reef at Olowalu, which was identified as a priority restoration area by the State. Coral restoration has been helping to regenerate damaged reefs in other parts of the world for more than two decades. TNC is working with partners to accelerate its use in Hawai’i by building the skills, knowledge and expertise necessary to collect and propagate coral fragments and outplant them on reefs after a damaging event, such as a marine heatwave, hurricane or ship grounding.

This comprehensive suite of activities—reducing local pressures, implementing nature-based solutions, actively restoring coral reefs and securing new sources of revenue to fund this work—arms us with the tools and strategies to give this Hope Spot the protection it warrants so it can continue to seed other reefs and protect and provide for the community.

Learn more about our science and restoration and how we help strengthen conservation management and leadership so Hawaiʻi’s reefs can support healthy fisheries and prosperous communities long into the future.