Main Hawaiian Islands

Volunteers plant native plants and test water quality in Hawaii


Hawaiʻi is a critical site for global coral reef conservation with some of the highest marine endemism recorded anywhere on Earth and about 85 percent of the United States’ coral reefs. Hawaiʻi’s reefs are fundamental to Hawaiian culture—ceremonies, food, and traditional gathering of marine resources are all dependent on healthy coral reefs. Hawaiʻi’s reefs also contribute over $800 million to the economy each year through the tourism industry. Coral reefs also serve as a natural barrier that protects people and coastal property from storm surges and floods. The U.S. Geological Survey calculated the economic value of shoreline protection in Hawaiʻi from coral reefs to be worth $900 million.

CORAL has led coral reef conservation efforts in the Main Hawaiian Islands for over fifteen years. Since 2006, we have designed our program in Hawaiʻi to protect and seed the coral reefs of Hawaiʻi’s future. Our values around community, volunteerism, and innovation drive our passion for partnering with local communities to protect local resources. Under CORAL’s Clean Water for Reefs Initiative, we focus on preventing land-based pollution from entering the ocean on both Maui and Hawaiʻi islands. Water pollution from sewage and stormwater runoff causes severe damage to coral reefs, poses risks to human health, and threatens the tourism industry and the Hawaiian economy. These pollutants cause widespread “brown water events” in coastal areas, threatening human health and harming coral reefs. Clean water is critical to coral reef health, and water pollution not only threatens our existing reefs but prevents them from adapting to the effects of climate change.

We work with the State of Hawaiʻi as well as two priority sites in Hawaiʻi – Hawaiʻi Island and West Maui – which form the beginnings of a Hawaiian Adaptive Reefscape — a network of healthy reefs that can adapt to climate change because it is diverse, connected and large.

The Problem

Hawaiʻi’s reefs face significant global and local threats including climate change, overfishing, sediment and nutrient pollution caused by sewage and stormwater runoff. Across the Main Hawaiian Islands, 88,000 cesspools release an estimated 53 million gallons of raw sewage into Hawaiʻi’s waterways every day. Sewage pollution contributes to high nutrient, bacterial, and pathogen levels in the nearshore marine environment—a serious health hazard to people and reefs. In some coastal areas, it is often mere hours before that sewage reaches the ocean and coral reefs. On Hawai`i Island, sewage pollution has been identified as the biggest contributor to declining fish biomass, and has been specifically linked to coral disease and bleaching, as well as alarming human health issues.

In other parts of the island chain, such as West Maui, red-brown hills rise up to the peaks of Mauna Kahalawai. The slopes historically supported pineapple and sugar cane plantations but, since the industry shuttered, they are now degraded and hard-packed soils. When it rains, flash floods carry stormwater downstream to the ocean. Just offshore lie once-thriving coral reefs that are now struggling to survive. Due to historical patterns of ocean currents, West Maui’s corals are critical sources of larvae for reefs on several islands, including Lānai`i, Molokai`i, Kaho`olawe, and Maui. West Maui has been designated a priority conservation site by both the state and federal government in an effort to address land-based pollution and corresponding declines in coral cover.

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Our Solution

In 2017, Hawai‘i passed legislation requiring all cesspools be replaced by 2050. In 2018, Hawai‘i passed a law establishing a Cesspool Transition Working Group that will develop a strategy for replacing cesspools. In collaboration with our nonprofit and government partners, CORAL helps demonstrate how to thoughtfully transition these cesspools with community engagement and support.

On Hawai‘i Island, we work closely with the Puakō community to address wastewater pollution. Because of the high groundwater table and very porous rock found along the coast, inadequately treated wastewater from cesspools and septic tanks does not get filtered by soil. Instead, this wastewater flows directly into the groundwater and then ends up in the ocean – causing serious damage to corals, negatively affecting marine life and posing risks to human health.

In Puakō, CORAL supports a formal Advisory Committee, which includes researchers, industry experts and community representatives to address impacts caused by outdated technologies, such as cesspools and septic systems. Based on a Feasibility Study and Preliminary Engineering Report, the Advisory Committee recommends building an onsite wastewater treatment facility to remove sewage from the shoreline and treat the wastewater to allow for water reuse. We are working with community members to turn this vision into a reality, and have developed a science-based monitoring plan (which includes a citizen science component) to measure the ecological and socioeconomic benefits of improved wastewater management.

To highlight the need for improved wastewater management and to provide quality data to guide management and empower local communities, CORAL and partners launched a citizen science program on Hawai`i Island in 2019. The program, called Hawai‘i Wai Ola, brings together eleven different organizations, volunteer community members, and scientists to champion water quality issues on Hawai‘i Island. Right now, the Hawai‘i Department of Health samples and reports on water quality at sites around the island under the national BEACH Act program. Due to scarce resources, sampling is limited. Water quality monitoring through citizen science provides a powerful and cost-effective solution to the state’s resource limitations, while increasing public awareness about threats to marine water quality.

In West Maui, our work focuses on restoring natural filtration processes within watersheds to prevent land-based water pollution from degrading reefs. High levels of sediment runoff can reduce corals’ access to sunlight by smothering them, negatively impacting reef health. High nutrients cause algal blooms which can overtake coral and promote coral disease. We take a “ridge to reef” approach to restore the natural function of an ahupua‘a (watershed) to filter stormwater and absorb nutrients, sediments and other chemicals. At the shoreline, we provide guidance to shoreline property owners, the tourism industry and Maui County on how to implement reef-friendly landscaping design which naturally filter stormwater before it reaches the ocean. Further inland (midslope), our work focuses on stream restoration to reduce the amount of sediment and nutrients flowing into the ocean. CORAL is working with farmers, Hawaiian communities, local nonprofits, private businesses and the government to pilot stream restoration techniques that combine modern technology with native vegetation and traditional agricultural practices. To increase filtration processes in and around stream beds, we are re-establishing native vegetation and taking lessons from Hawaiʻi’s long history of traditional agricultural practices. Traditional wetland taro patches (loʻi kalo) absorb nutrients and trap sediment and are deeply embedded in Hawaiian culture. We are also planting deep-rooted vetiver grasses, which trap and stabilize sediments and enable native vegetation to thrive.

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  • 2006: CORAL begins working in Hawai‘i with an initial focus on sustainable marine recreation
  • 2009: CORAL and partners train over 350 tourism professionals in sustainable marine recreation and install reef etiquette signs in more than 50 highly visible locations across Hawaiʻi
  • 2009: CORAL helps establish the Kahekili Herbivore Fisheries Management Area (KHFMA) in Kaʻanapali, West Maui; herbivorous fish are vital to coral reef ecosystems as they feed on algae and prevent it from overtaking coral reefs
  • 2010: CORAL expands its work to address water pollution because of the significant threat it poses to coral reefs and the lack of attention surrounding the issue
  • 2014: CORAL launches the Clean Water for Reefs Puakō project to develop a solution to replace cesspools in Puakō with improved wastewater treatment infrastructure
  • 2015: CORAL begins working with the Maui County Department of Public Works to integrate reef-friendly landscaping design into county ordinances and permitting processes
  • 2015: Puakō Feasibility Study and Preliminary Engineering Report is released, and the AQUA Engineering recommends an onsite treatment facility
  • 2016: CORAL motivates 17 shoreline property owners on Maui Island to invest over $19 million in reef-friendly landscaping, resulting in 277 acres of land under improved management filtering over 35 million gallons of stormwater per year
  • 2016: CORAL forms an expert knowledge sharing group in West Maui to design and implement a stream restoration plan to reduce the amount of sediment and nutrient pollution reaching coral reefs
  • 2017: The Coral Reef Alliance and its partners presented the costs to determine the financial feasibility of the recommended solution at the Puakō Wastewater Forum on January 14
  • 2018: CORAL presents fundraising goal of $11 million dollars (to reduce costs for homeowners) at the annual Wastewater Forum on January 5. Dr. Steven Colbert of University of Hawaiʻi Hilo presents latest research in Puakō, and state and county officials participate in a panel discussion about wastewater issues in the state and county
  • 2018: Hawaiʻi Department of Health passes Act 132 establishing a Cesspool Conversion Working group to develop a long-range, comprehensive plan for statewide cesspool conversion by 2050. CORAL is one of two NGO’s participating in this effort.
  • 2019: CORAL works with partners to launch Hawaiʻi Wai Ola, a collaboration of eleven different organizations, community members and scientists to champion water quality issues on Hawaiʻi Island.
  • 2019: The state appropriates $1.5 million in Capital Improvement Project (CIP) funds for Hawaiʻi County to conduct a planning and design study for Puakō’s sewer system. In this same year, Senator Inouye and Representative Tarnas both prioritized $15M in construction funds in the 2020 Legislative Session. COVID-19 paused the momentum of this project, and these bills will be resubmitted.
  • 2020: With the onset of the pandemic, CORAL shifts and adapts the volunteer program in West Maui to provide volunteers with the seeds to grow native plants at home. It is estimated that approximately 10,000 plants will ultimately be transplanted to ur watershed restoration site as a result of this initiative.
  • 2020: Hawaiʻi Wai Ola collects baseline data of shoreline healthy during COVID-19, offering a unique dataset of minimal human use during the pandemic shutdown.

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erica_perez-closecrop Headshot_JenVanderVeur_Web_020918
Erica Perez
Senior Program Manager
Hawaiʻi Island
Jennifer Vander Veur
Senior Program Manager
Maui, Hawaiʻi
Larissa Treese
Program Coordinator
Maui, Hawaiʻi
Chelsea Eareckson
Research Officer
Maui, Hawaiʻi

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Map of CORAL's Field Sites in the Main Hawaiian Islands

CORAL’s Field Sites in the Main Hawaiian Islands

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Additional Resources

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