Hawaii’s Love Affair With Cesspools Is Ruining Its Reefs

Reefs are paying the price for new housing developments — and state marine protection alone can’t stop human waste from speeding up their demise. A coral reef at the base of a Big Island lava field is one of Hawaii’s healthiest — and most at risk.

It’s located off Milolii, considered the state’s last fishing village and home to Native Hawaiians since the first millennium. Their descendants fought to create a state-protected fishing reserve there just two years ago, making it the largest locally managed marine refuge in the main Hawaiian islands.

New threats to the reef’s rich biodiversity loom just uphill from Milolii’s weatherworn houses and streets strewn with boats and fishing gear. There, a growing subdivision of large houses, some featuring cathedral windows and wraparound lanais, brings an unwelcome neighbor: Poop. Lots of poop.

---

As a nonprofit journalism organization, we depend on your support to fund our nationwide Connected Coastlines climate reporting. Donate any amount today to become a Pulitzer Center Champion and receive exclusive benefits!

---

Cesspools and septic tanks, both in the subdivision and the older village, send untreated human waste into the groundwater. From there, the wastewater percolates to the ocean and onto the reef, transporting a range of pathogens, chemicals and other pollutants.

It’s only the beginning, too. About 235 homes dot the steep, volcanic slope today. Dozens more are permitted or under construction and another 700 lots are available for development.

Although new homes are desperately needed on an island with a severe housing crunch, the construction boom bodes poorly for the reef. Its calcium carbonate structure, built from coral polyp skeletons, provides food and shelter for sea life while also protecting the village from storms. It’s a mother reef, which seeds other reefs down the coast by injecting huge sprays of larvae into the water column.

So far, the reef off Milolii, located in Pāpā Bay, is still healthy despite the regular doses of untreated wastewater on top of the persistent reef assaults of climate change, including warming waters and acidification.

But travel 70 miles north up the coast to Puako for a glimpse of a possible future. Reefs there have been decimated not just by ocean heat waves but by wastewater from cesspools and septic tanks alongside sediment washing down from higher elevations.

Native Hawaiians consider Puako a wahi pana, a sacred or legendary place. But the dire situation there has earned it a nickname: “Poop ako.”

“…When we put the dye into the cesspool, in a matter of nine hours that dye was then coming out at the shoreline.”

Steven Colbert, a University of Hawaii Hilo scientist

Constant seepage from wastewater makes Puako one of the worst stretches of coastline in the entire state for sewage impacts, said Steven Colbert, Ph.D., a University of Hawaii Hilo scientist who has done dye tracer tests there.

The tests, in which scientists inject a colored dye into groundwater to track its flow, have shown why Puako typically logs one of the highest bacteria counts on the Big Island.

“At some of the cesspools that we analyzed, and one of them in particular, when we put the dye into the cesspool, in a matter of nine hours that dye was then coming out at the shoreline,” Colbert said.

In other words, if someone flushes their toilet during high tide, he said, the waste would reach the ocean by low tide.

The reef’s coral cover has declined from 53% to less than 5% in recent years, according to University of Hawaii Hilo research. Scientists say it’s on the verge of collapse.

Puako’s low-lying landscape and topography add to the problem. There’s little distance between the ground surface and the water table underneath, making it virtually impossible for soil to filter out pollutants before they reach the groundwater.

Scientists and some policy makers are hoping that the Big Island can learn from Puako’s mistakes so that other reefs don’t fall victim to the same fate.

Reef Threats From Land May Eclipse Climate Change

Coral reefs around the world face threats of mass extinction from climate change. By some estimates, around half of the world’s reefs are already dead and many scientists believe that without drastic action nearly all could die by 2050.

Ocean warming and overharvesting of fish that eat algae on reefs are often cited as the main culprits. Land-based stressors that are equally harmful tend to get less attention.

In places like Milolii — as elsewhere in Hawaii, with its tens of thousands of cesspools and leaky septic tanks — some scientists say that human waste joins sedimentation and polluted runoff from storms and agricultural lands to pose the greatest threat to coral reefs.

When wastewater hits a reef, the household chemicals, detergents, pharmaceuticals and other pollutants it usually contains make corals vulnerable to disease. That’s one threat. Nitrogen and phosphorus in sewage provide the double whammy. These “nutrients,” as scientists like to call them, act like fertilizer, stimulating the growth of algae.

The marine plant life blocks the sunlight that corals need to photosynthesize and create food. If the algae grows enough, it also can smother and kill coral reefs.

Hawaii has more than 80,000 cesspools, the most per capita of any state. The majority – some 50,000 of them – are located on the Big Island, according to the Hawaii Department of Health. The County of Hawaii maintains just 120 miles of sewer lines on an island roughly the size of Connecticut, which has thousands of miles of lines.

Until the cesspools, which are basically holes in the ground, and septic tanks are eliminated or modified to recycle the wastewater, the island’s coral reefs will continue to decline. That is an expensive and complicated process.

But Hawaii has its share of reef evangelists who are trying to turn the tide. Greg Asner is one of them.

Downhill From A ‘Potential Timebomb’

A former Navy deep-sea diver who has worked with NASA, the U.S. State Department and the United Nations on science and conservation issues, Asner lives in Milolii and runs an oceanographic and terrestrial research lab there.

As director of Arizona State University’s Center for Global Discovery and Conservation Science, Asner has written hundreds of peer-reviewed scientific papers about coral reefs and marine ecosystems, including a landmark article published in the journal Nature in August 2023.

The paper synthesized 20 years of data to document the ways coral reefs are being fundamentally altered by local human impacts.

That has led the longtime Hawaii resident to push for reform in how wastewater is handled in the state’s coastal areas.

Hawaii County Council member Michelle Galimba calls the reef off Milolii a poster child for other threatened reefs in Hawaii, a state that relies on beaches, coral reefs and colorful marine life to attract millions of visitors annually. Asner describes it as being “downhill from a potential timebomb.”

While the future for coral reefs is grim, Asner thinks it’s not too late, at least for Milolii’s. The first step is improving sewage technology.

Asner works closely with Hawaiians with lineal ties to Milolii. One of them is Kaimi Namaielua Kaupiko, a teacher and president of Kalanihale, a nonprofit that co-manages Milolii’s fishing area with the state Division of Aquatic Resources.

“We’re very passionate about making sure we take care of this area for our future generations of ohana.”

Kaimi Namaielua Kaupiko, a teacher and president of Kalanihale

Kaupiko and his family were instrumental in getting the fishing reserve established in 2022.

The goal was to protect pāku‘iku‘l (Achilles tang), kole (yellow-eyed surgeonfish), uhu (parrotfish), opihi (limpet), ula (spiny lobster) and other reef species and to honor traditional Hawaiian values and fishing practices.

“We’re very passionate about making sure we take care of this area for our future generations of ohana,” Kaupiko said.

Despite that success, he knows that Milolii is quickly changing, and the health of the coral reef and the nearshore waters is in jeopardy. Swimmers exposed to sewage-tainted seawater have reported staph infections and gastrointestinal ailments including vomiting and diarrhea.

“We’ve had families who have gotten sick,” Kaupiko said.

Until two decades ago, Milolii was relatively isolated. Located about 38 miles south of the tourist haven of Kailua-Kona with its waterfront restaurants, cruise ships, jewelry stores and gift shops, sleepy Milolii remains a world apart. It’s not known for being particularly friendly to tourists.

Life started to change dramatically after the local utility brought power lines in around 2005, which kicked off a housing boom. Newcomers bought barren, sunbaked lots and built homes on the lava. That drew more people, houses and cars to Milolii — and sewage.

Today, Asner estimates that tens of thousands of gallons of wastewater is discharged daily from Milolii toilets into the porous rock.

His research and that of others indicates that, as in Puako, waste quickly finds its way through the lava substrate into the groundwater and out onto the reef.

The State of Hawaii’s Cesspools

Cesspools inject about 52 million gallons of untreated wastewater into Hawaii’s nearshore waters daily, according to Stuart Coleman, director of Wastewater Alternatives & Innovations.

Coleman is on a mission to stop it.

At the urging of Coleman and others, a statewide ban on the construction of new cesspools was signed into law in 2017. One year later the state passed another law, Act 125, requiring that all cesspools be converted to septic tanks by 2050.

Weaning Hawaii from cesspools has been extremely slow. For one thing, it’s costly to convert a cesspool into a septic tank. Some estimates put it at around $50,000 per conversion, or more.

For new homes being built in places without access to county sewer lines, souped-up septic tanks that rely on a process called denitrification may be the way to go.

Denitrification has been used successfully to help clean up parts of the Chesapeake Bay in Maryland and on Long Island, New York, places where Coleman said wastewater from cesspools and septic tanks decimated shellfish industries.

“We can learn from them,” he said.

Tanks equipped with denitrification technology convert nitrogen in the effluent to gas, which is then released into the air. That process removes about 90% of nitrogen from the wastewater, Coleman estimated, and adds only about $3,000 to $5,000 to the construction cost of a new home.

Another alternative for Milolii could be a wastewater treatment system for the community, independent of the county sewer system.

Connecting Milolii to the county’s sewer lines and the nearest treatment plant would be incredibly expensive: It costs about $1 million per mile to lay sewer pipe.

A decentralized system would be much cheaper — and more practical. There’s a model called a Pressurized Liquid Only Sewer system, or PreLOS, that Coleman said could work.

Each home in Milolii would have a collection tank attached to underground PVC piping to carry the wastewater to a treatment plant that would convert it into recycled water, suitable for landscaping and other types of irrigation.

A decentralized treatment plant is being pursued at Maalaea, a community of condominium buildings on Maui that once had a thriving coral reef. But much of the reef died over the years because the condos used injection wells, which force effluent into the groundwater, which makes its way to the ocean.

John Starmer, science director of Maui Nui Marine Resource Council, said he’s encouraged by the Maalaea community’s work to take charge of its wastewater and properly deal with it. It could set an example for other parts of Hawaii.

“Progress is actually being made,” Starmer said.

A Legislative Fix Falls Short

Last year, Hawaii County Council members Heather Kimball and Michelle Galimba took steps to address Milolii’s wastewater problems.

They drafted a bill that required homes built close to the shoreline to have individual wastewater systems equipped with denitrification technology.

The two Big Island council members got state Rep. Nicole Lowen to introduce it as House Bill 1691.

The bill received support and some suggestions for amendments from various corners, including the Hawaii Department of Land and Natural Resources, Hawaii Department of Health, Hawaii Sea Grant and the University of Hawaii Water Resources Research Center.

It passed both the House and Senate but died in the Senate Ways and Means Committee.

Kimball said she has no plans to give up.

The bill authors pledged to try again this upcoming session and recently included it in a proposed package of priority bills the Hawaii Association of Counties plans to introduce. That package still needs to be approved by all four counties in Hawaii.

If the Legislature fails to pass it this time, the Big Island council members say they will craft a county ordinance.

Milolii is where Asner not only has his research lab, but also supervises doctoral students and trains high schoolers as marine conservation interns. He is adamant the village’s world-class reef doesn’t have to be the next Puako.

He’s trying to educate Hawaiian decision-makers and residents about the danger of allowing housing development with inadequate wastewater treatment adjacent to a near-pristine reef ecosystem, not to mention a fishing reserve that serves Native Hawaiians with ancestral ties to the area.

But there are limits to what Asner can do.

“I’m the science guy,” he said, not a wastewater engineer or a politician.

No More ‘Free Ride’ For Cesspools

During a 2023 presentation to the Hawaii County Council, Asner said the county’s newly created Office of Sustainability, Climate, Equity & Resilience could help Milolii build a decentralized treatment plant or craft a program to incentivize homeowners to install their own denitrifying septic tanks.

Bethany Morrison, interim director of that office, said she’s exploring funding from the Environmental Protection Agency and other federal sources. One option might be a public-private partnership to create a Milolii improvement district where residents would tax themselves to pay for some of the denitrification costs.

More public awareness about connections between reef health and wastewater would increase buy-in from residents, said Coleman, who believes people with cesspools have gotten a “free ride” for too long.

“We need to normalize sewer fees,” he said. “You pay for your clean drinking water and you pay for your dirty water removal.”

Nicole Crane, a marine biologist who also lives in Milolii, said the Native Hawaiians who fought for the subsistence fishing area should have a “central seat at the table” where decisions are made about regulating wastewater discharges from both the old fishing village and the growing subdivision above it.

In her view, it’s an environmental justice issue.

“The people of Milolii have a lot of agency now, finally, in managing that reef,” said Crane, executive director of One People One Reef, a nonprofit that supports reef conservation in Micronesia. “They’re trying to do the right thing in managing it and the people who are currently providing a lot of the ‘nutrients’ are not Native Hawaiians.”

“We need to normalize sewer fees. You pay for your clean drinking water and you pay for your dirty water removal.”

Stuart Coleman, director of Wastewater Alternatives & Innovations

Kaupiko and his nonprofit are closely monitoring how creation of the 18-mile fishing reserve will affect the area’s fish population. Since reef health and water quality are central to healthy fisheries, Kalani Hale is working with Asner and Crane on initiatives to monitor and protect the reef.

Western science supplies critical information and data points but it also confirms what Milolii’s kupuna have always known about the ocean and the underwater environment, and underscores why they asked the younger generation to take steps to protect it.

“Our elders who are not here with us anymore,” Kaupiko said, “they really, really warned us to step up and do something.”