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Just offshore from some of Oʻahu’s most iconic south shore beaches, up to 90 million of gallons of treated wastewater are discharged into the ocean every single day.
The Sand Island Wastewater Treatment Plant is coming into focus right now, as the Hawaiʻi Department of Health considers renewing its pollution discharge permit. While the term “treated wastewater” sounds reassuring, the reality is more complicated and more concerning.
Take action with Surfrider and urge DOH to protect our communities and reefs with clean water now. Read more for key issues and comment talking points.
Link to notice of permit renewal
Comment Deadline: April 15
Treated but not clean
The Sand Island facility processes wastewater from most of urban Honolulu and discharges it through an ocean outfall about 2 miles offshore in Mamala Bay. But how that water is treated matters, and right now, it is not being treated to the highest standard.
There are different levels of wastewater treatment. Primary treatment removes solids but does not fully remove bacteria or many contaminants. Secondary treatment goes further, significantly reducing pollution before discharge.
The Sand Island plant is currently operating with primary treatment (with some enhancements) and is not yet at full secondary treatment, which is not expected to be upgraded until 2038 or later.
In the meantime, the system relies on a mixing zone- a regulatory allowance that permits pollution to exceed water quality standards within a defined area, based on the assumption that it will be diluted by the surrounding ocean. But dilution does not remove pollution. Ocean currents can carry contaminants beyond the expected zone, and people and marine life within it are still exposed.
The current permit allows for extremely high levels of bacteria, including enterococcus, a fecal indicator of potential pathogens that can make people sick. The proposed daily maximum is 28,730 MPN/100 mL, compared to a state water quality standard of just 130 MPN/100 mL— far above what is considered safe in waters where people recreate.
Recent monitoring shows this isn’t just theoretical. In July 2025, a recorded sample reached 78,622 MPN/100 mL (EPA data). There have also been numerous effluent violations, underscoring ongoing challenges with maintaining water quality standards.
The facility does use ultraviolet (UV) disinfection, which is intended to reduce bacteria in treated wastewater. But these numbers raise serious questions: if UV treatment is in place, why are bacteria levels still so high? Is the system not fully implemented, or is it being overwhelmed by operational challenges?
Close to Home: Waikīkī, Ala Moana, and the South Shore
This isn’t a problem happening somewhere far away. The discharge point sits just offshore from the South Shore, in the same ocean waters that connect to Sand Island, Keʻehi Lagoon, Ala Moana Beach Park, Kewalo Basin, and Waikīkī beaches.
Research in Mamala Bay shows that wastewater discharged from the Sand Island outfall can move back towards the shore, including to areas like Ala Moana, Waikīkī, and Queen’s Surf. In some cases, the outfall has been identified as a dominant source of pathogens at these beaches.
These are places where residents swim, surf, paddle, and keiki play. High bacteria levels can make people sick, causing gastrointestinal illness, skin infections, ear infections, and more.
For decades, the assumption has been that discharging wastewater far offshore keeps it away from people. But what goes out to sea does not always stay there — and what happens offshore matters here.
A Long-Standing Issue
For decades, the City and County of Honolulu has faced legal challenges for failing to meet Clean Water Act requirements for its wastewater system. Environmental groups, including Sierra Club, Hawaiʻi Thousand Friends, and Our Children’s Earth Foundation, brought litigation over ongoing violations, ultimately prompting EPA involvement and a federal settlement in 2010 through a consent decree.
That agreement established a long-term plan to bring the system into compliance, including interim measures like polymer addition and ultraviolet (UV) disinfection, as well as major infrastructure upgrades and full secondary treatment over time.
But the timeline extends decades into the future, with full compliance not required until 2038. In the meantime, this permit allows continued pollution that puts our health at risk. We cannot wait until 2038 for clean water.
Take Action Now: Submit a Comment
Email: cleanwaterbranch@doh.hawaii.gov or by mail at P.O> Box 3378 before April 16, 2026
There are clear, achievable solutions — and this is where public comments matter.
When submitting comments on the permit, you can highlight:
- Make it personal
Make it personal. Share how you recreate in Mamala Bay, and whether you or your loved ones have ever gotten sick after being in the ocean. No one should have to worry about getting sick when they go to the beach. - Lower bacteria limits
The permit should require limits that reflect what is safe for people, not what can be diluted offshore. Current limits (28,730) are far above the water quality standard (130). - Mixing zone is not protective
Pollution should not be allowed simply because it is diluted offshore. Dilution does not remove contamination, and pollutants can move beyond the expected zone. - Public health risks are real
High bacteria levels can make people sick. These waters are used every day by swimmers, surfers, paddlers, and keiki along the South Shore. - We can’t wait until 2038
Full secondary treatment is still years away, but water quality impacts are happening now. - Require effective use of existing technology
The facility already uses UV disinfection. It should be required to consistently meet protective water quality standards. - Address pollution at the source
Strengthen oversight of industrial discharges and pretreatment programs to prevent harmful contaminants from entering the system in the first place. - System-wide accountability
This is not just a treatment issue — it includes aging infrastructure, infiltration, and upstream pollutant sources.