Thousands of cesspools throughout the islands are threatening drinking water supplies, coral reefs and the health of people who swim and surf in popular places, according to a new analysis by the Hawaii Department of Health.

It’s a serious public safety issue, environmental problem and economic danger that’s exacerbated by the effects of climate change, officials said.

In its 36-page report last week to the Legislature, the Health Department estimates $1.75 billion is needed to replace all 88,000 cesspools around Hawaii, with upgrades required urgently for about half of those. Some 53 million gallons of raw sewage are being discharged each day into cesspools, essentially just holes in the ground for wastewater.

“It’s a good chunk of change to swallow for the Legislature but that’s the magnitude of what we’re dealing with,” said Keith Kawaoka, deputy director of the department’s Environmental Health Administration.

The reality is government will not be able to foot the bill to overhaul everyone’s system, but he said he hopes a combination of tools can be used to turn the tide.

The highest priority areas are upcountry Maui, where 7,400 cesspools have caused nitrate levels in well water to spike dangerously close to safe-drinking limits, and Kahaluu on the east side of Oahu, where there have been “incidents of skin infections consistent with sewage-contaminated surface waters.”

The department plans to hold public meetings next month to gather community input, starting Jan. 9 in Makawao and Jan. 12 in Kahuluu.

While water is still safe to drink throughout the state and it’s OK to swim in almost all areas, health officials said, the risk of disease is expected to increase as cesspools deteriorate and become more prone to flooding as the sea level rises and storms intensify.

“Climate change will impact things,” said Bruce Anderson, who heads the Department of Land and Natural Resources’ Division of Aquatic Resources and formerly led the Health Department.

Hawaii depends on wells for more than 90 percent of its drinking water and the vast majority of homes are near the ocean. As the sea level and water tables rise, there is an increased opportunity for more wastewater to contaminate healthy sources.

“This is going to go from bad to worse unless someone figures out how to deal with it,” Anderson said.

But solutions to this decades-old problem are elusive. 

Lawmakers have tried encouraging community members to replace their cesspools by offering a $10,000 tax credit but only 47 people have taken advantage of it since it was enacted in 2015.

The Health Department had proposed a rule to phase out old cesspools by requiring an upgrade to a septic or other wastewater system upon the sale of the property but it was never signed. That effort  languished on former Gov. Neil Abercrombie’s desk before Gov. David Ige took office in December 2015.

Kawaoka said that plan did not go over well with the public and likely won’t be attempted again anytime soon.

Gladys Baisa, who was Maui County Council chair when those rules were being put forward, said at the time that it would have been a financial hardship for many Valley Isle residents.

More than 3,000 large-capacity cesspools have been closed since a 2005 law banned them.  But the Environmental Protection Agency has had to fine businesses and restaurants thousands of dollars to force compliance in some cases, such as with Travassa Hotel Hana Resort on Maui, Vacation Inns International on Oahu and Shaka’s in Pahoa on the Big Island.

The state prohibited new cesspools in certain areas in 1992 and extended the ban to apply to all of Hawaii in 2016. Kawaoka said the department had been receiving requests for several hundred new cesspools each year.

And lawmakers passed a bill last year to eliminate all cesspools by 2050, with some exceptions. The law calls for exploring a grant program to help low-income property owners.

But grant programs have also struggled. Last week, the Health Department canceled a nearly $500,000 contract it had with the Hanalei Watershed Hui, headed by Makaala Kaaumoana, that was set up to help north shore Kauai residents upgrade their systems.

“Apparently, from our Hanalei experience, people don’t do it unless they are forced,” Kaaumoana said, noting that the Health Department was very patient as her nonprofit tried for over a year to secure applicants. “It’s clear to us that people think the government should do it.”

The Health Department report notes that 270 cesspools in Hanalei pose a “high probability of contamination.”

But government officials and community leaders cautioned that even if they could somehow convince people to replace their free cesspools, the next best option is converting to a septic system, which still presents problems.

Septic systems are undoubtedly better environmentally, as solids drop to the bottom of the tank and liquids are then filtered through a leach field. But it still means dumping millions of gallons of raw sewage into the ground each day.

“Both cesspools and septic tanks result in allowing effluent to get into the ground and into the groundwater, which can get it to the ocean,” Anderson said. “That’s the risk.”

Connecting to a local wastewater system is best, officials said, but that is not feasible in many rural areas.

There are almost 50,000 cesspools on the Big Island alone, accounting for 27.3 million gallons of cesspool effluent daily — more than half of the state’s load, according to the department’s report.

And yet the island has just 187,000 of the state’s 1.4 million residents, not to mention a smaller share of the 8 million annual visitors to Hawaii.

The Health Department found 25 percent of domestic wells sampled in the Keaau area of Big Island, for instance, tested positive for wastewater indicator bacteria, “demonstrating the potential for disease transmission.”

Many residents rely on domestic wells in the area, and there is “little soil to mitigate the impact of 9,300 cesspools,” the report said.

But the threat is widespread on the Big Island, as it is on the other islands. It’s also indiscriminate, hitting wealthier neighborhoods like Kahala on Oahu and Kona on the Big Island, which is one of the fastest growing areas in Hawaii and home to some of the best snorkeling in the state.

The Health Department report notes 6,500 cesspools are discharging into the nearshore waters of west Hawaii Island and “may contribute to degradation of coral reefs.”

“The impacts to coral reefs affects the state’s economy, shoreline protection, recreation and habitat for important marine life,” the report says.

Coral reefs there and around the state, including Kahaluu Lagoon and Diamond Head on Oahu, are threatened as the cesspools overload nearby waters with nutrients — nitrogen and phosphorous — that cause algae to take over and smother new growth.

“Anyone who enjoys our nearshore resources is impacted,” Anderson said. “There’s no question. People fishing, enjoying the beach… it’s not a small issue.”

But as Kawaoka said, it’s an economic issue as much as an environmental one.

Hawaii Island Mayor Harry Kim has testified before the Legislature in opposition to a ban on cesspools.

“Yes, I realize that Hawaii has changed and we are now in the 21st century, but those of us who grew up in ancient times know that some of the old practices, while not entirely compatible with modern thought, are nevertheless environmentally sound and do not need to be discarded,” he said in his testimony last year on the bill to ban cesspools by 2050.

“As a prime example, in Hawaii County we have literally thousands of lots on which cesspools pose absolutely no hazard to groundwater nor any risk of pollution,” Kim said. “Many of these lots may represent the best hope for current and future Hawaii residents to live in a dwelling rather than on the street.”

Officials said the problem stems from the way in which Hawaii grew. It would not have made sense to install a municipal or private sewage system 50 years ago in Haleiwa, for instance, as there were hardly any homes on the north shore of Oahu.

But now there is more density in the area, much like what happened in other communities around the state.

“The cesspool issue didn’t happen overnight,” Kawaoka said, “and it’s not going to be overnight to solve it either.”

Sen. Donovan Dela Cruz, who chairs the Ways and Means Committee, said the the government and the public need to share responsibility in addressing the problem.

“It’s not a good situation,” he said. “But we can’t just keep kicking the can down the road.”

Dela Cruz said there probably needs to be a “carrot and a stick” approach. Perhaps, he said, there could be stronger incentives for a certain number of years followed by enforcement of a law requiring upgrades.

“As long as everyone is treated fair and it’s transparent and it’s reasonable,” he said.

Short of the state spending massive sums of money on infrastructure, Anderson said he envisions a slow process. The good news, he said, is new homes are on sewage systems and rebuilding an old home would require an upgraded system.

“I’m not sure there’s anything the Legislature can do,” he said. “I think they’ve used the tools that are readily available.”