Before the Clean Water Act of 1972 became law, most of the agricultural wastewater and sewage from the Kaʻanapali coast on Maui, Hawai‘i was treated to remove only solids before being piped out into the ocean. After the wastewater started being injected into wells to comply with the new law, nearby residents started noticing algal blooms and destruction of the coral reefs in the waters along the once-healthy shoreline. That was the beginning of what would become decades of research by coral biologists, limu (seaweed) experts, and scientists who studied the exchange of groundwater between land and sea. They needed to definitively identify the source of the pollution so that it would withstand the scrutiny of the U.S. Supreme Court almost 50 years later.
When Maui’s sugar and pineapple industries started to decline in the mid-1950s, tourism emerged as a possible new economic base, and developers identified the Kaʻanapali coast as a potential resort destination area. Hotels popped up along the coast and the tourist population grew just as quickly, creating a significant amount of new sewage in addition to the ongoing agricultural wastewater. The Clean Water Act of 1972 was enacted for the primary purpose of controlling discharges of pollutants into surface waters, specifically prohibiting point source pollutants (any contaminant that enters the water from an easily identified place) from being discharged into the nearshore waters without a permit. With this new law came federal funding to local municipalities to help pay for the costs of cleaning their wastewater.
“Maui decided to upgrade their systems and use the water for reuse,” says Russell Sparks, an aquatic biologist in the Maui office of the State of Hawaiʻi Department of Land and Natural Resources, Division of Aquatic Resources (DAR). “That’s why they call themselves the Wastewater Reclamation Division. But they never really followed through with infrastructure to distribute the [reclaimed] water.”
The county constructed the Lahaina Wastewater Reclamation Facility in 1975 approximately three miles north of Lahaina in West Maui to provide municipal wastewater services to the Lahaina community and the resorts along the coast. The treated wastewater is partly reused for landscaping and golf course irrigation, and the rest is disinfected and discharged into one of four injection wells. Wastewater is injected into vertical pipes that reach 180 to 385 feet into the earth where it mixes with groundwater before flowing into the ocean. Although the wastewater is treated for viral and bacterial pathogens that are harmful to human health, it is not treated for other nutrients or contaminants.
George Brown was a civil engineer at Pioneer Mill during the 1970s and 80s. “Maui County’s sewage effluent plan was to have the water piped up to the Honokohau Ditch, which served the sugar that came from Honokohau valley,” says Brown, who was involved with planning the pipeline. “The injection wells were to be used for a temporary fix only if the pump broke or they had a problem. Sometime after that, the county decided they were not going to have the pipeline.” Instead, the injection wells became the county’s solution for disposing of wastewater, and since 1982, three to five million gallons per day of wastewater has been pumped into the wells.
The ocean directly offshore from the wells didn’t show any signs of effluent, but about half-a-mile to the south, the water started showing signs of deterioration. “There must be a submerged stream bed or some kind of geological feature that deflects the injected waste, which then emerges in the ocean at Kahekili Beach Park on North Kaʻanapali Beach” says Sparks. “It comes up in three feet of water, approximately fifteen feet from the shore outside a long stretch of white sand beach along the coast that fronts expensive hotels and condominiums.” The coastline’s clear water and accessible reef make it a popular swimming and snorkeling area for tourists and locals alike.
Many studies have been done since the 1990s that show the nutrient flow into these West Maui waters is from the Lahaina Wastewater Reclamation Facility wells, contributing three times more nitrogen than any other source into the ocean. “The wastewater percolates up from the bottom, through the reef, which is incredibly sensitive to those nutrients,” says Sparks. “Back in 1994, we were measuring about 55 percent of the bottom with living coral. Now it’s around 32 percent or somewhere in that area, which is about a 50 percent decline in coral. Injection wells are probably one of the worst ways we can dispose of our wastewater.”
Dr. Celia Smith, a professor at the University of Hawaiʻi at Mānoa, has conducted extensive research on the physiological ecology of reef algae and corals. “The limu would have been evolving on a long evolutionary time frame under natural conditions, which would have been lower levels of naturally occurring fertilizers that would come through the submarine groundwater discharges,” says Smith. The ecosystems started changing when land-based sources of pollution, primarily fertilizer, were put into the soil. By the time the injection wells started discharging effluent into the ocean, an inordinate amount of excess nitrogen was being introduced into the reef ecosystem. These conditions have favored invasive seaweed species, causing them to grow exponentially, sometimes doubling in two days. “Most of the native plants are not going to be able to thrive under those altered conditions. It’s no longer the Hawaiian ecosystem when we have polluted it at that level.”
The U.S. Geological Survey did a multitracer survey of the nearshore marine waters fronting Kahekili Beach Park in 2009 and found multiple contaminants in the wastewater plumes. The combination of excessive amounts of freshwater, nutrient pollution, and acidification was suffocating the reefs and creating algal blooms.
As the years went on, scientific evidence seemed to prove that the effluent from the Lahaina Wastewater Reclamation Facility injection wells was causing the high nitrogen concentrations, algae blooms, and destruction of the coral reefs. In 2011, the Environmental Protection Agency contracted the University of Hawaiʻi (UH) to collect data to definitively prove whether the treated wastewater was coming from the Lahaina Wastewater Reclamation Facility. The project team added tracer dyes to the injection wells to see if and where they might emerge at the coastline. The tests conclusively demonstrated that effluent from the wells started emerging along the North Kaʻanapali Beach 84 days after the dye was added, with peak concentrations occurring 9-10 months later.
“We did a lot of water geochemistry,” says Dr. Craig Glenn, professor at UH’s School of Ocean and Earth Science and Technology and principal investigator of the tracer study. His team took water samples from seeps where there was very strong groundwater flow coming out of the sea floor. They also used infrared cameras to check the surface water temperature. “I had aircraft fly over there in the middle of the night to map out how big the plume expression of the discharge was, and it showed a very large plume.”
Despite these findings, there were years of failed negotiations to find sustainable, long-term solutions to clean up the water. Then in 2012, the Hawaiʻi Wildlife Fund, West Maui Preservation Association, Sierra Club-Maui Group, and Surfrider Foundation joined forces to file suit in district court to challenge Maui County’s Clean Water Act violations. They argued that Maui County was discharging pollutants into the ocean through groundwater without a required permit. Maui County lawyers claimed the Clean Water Act only covers point sources that dump pollutants directly into surface waters, not water that passes through a non-point source, such as groundwater. The district court ruled that a permit was needed, which the county appealed to the Ninth Circuit Court, but the ruling held. Maui County then petitioned the U.S. Supreme Court for review, which it accepted. In April 2020, the U.S. Supreme Court, the highest court in the nation, ruled that the discharge is the functional equivalent of a direct discharge and sent the case back to the district court for further proceedings.
Over the years, the Lahaina Wastewater Reclamation Facility has improved treatment of the effluent before it is injected into the wells; however, both nitrogen and phosphorus remain at high levels. Scott Rollins, division chief of the Wastewater Reclamation Division of Maui County, says the county changed what went down the injection wells to R-1 quality, which is the highest quality of recycled water. “As part of the lawsuit settlement we have had to expand our distribution system, so we’re working on that. It’s very early in the design,” says Rollins. It must be completed by November 2025.
Dr. Andrea Kealoha, who runs the University of Hawaiʻi Maui College Water Quality Lab, conducted a study to find out if there would be a change in the nearshore waters fronting Kahekili Beach Park as a result of 100,000 fewer people on the island due to the COVID-19 pandemic lockdown. The Lahaina Wastewater Reclamation Facility was receiving 40 percent less wastewater per day, and injecting 60 percent less effluent into the well. Her team found a 97 percent decrease in nitrate concentration compared to a study that was done in 2016. “Even though we saw this massive reduction, it wasn’t that there was no nitrate, but the denitrifying bacteria were actually able to consume it before it was being released,” says Kealoha. “Five months after the quarantine was lifted, we saw nutrient concentrations start to come back up again, and within a year, they were back to what they were, and maybe even higher.”
David Henkin, the EarthJustice attorney who successfully argued the case before the U.S. Supreme Court on behalf of the environmental groups, says that EarthJustice is planning to bring additional lawsuits for similar situations around the state. “Now that we have the clear signal from the U.S. Supreme Court that we have these legal tools, we are going to use them.”
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