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Lāhainā Post-Fire Water Quality Monitoring

Since the August 8, 2023 Maui fires, Surfrider Foundation Maui Chapter has been receiving the same, seemingly simple question of ‘is the water safe?’ with increasing concern. There are a handful of groups that have obtained funding to test for fire contaminants in the ocean waters off of Lāhainā over the past few months. However, the focus has largely been on marine ecosystem and reef health, leaving a gap of public information in regards to human health impacts. (cover photo credit: Mark Deakos)

As a result, for the past three months, Surfrider Foundation Maui Chapter has been consulting with water quality experts, chemists, environmental toxicologists, bioremediation scientists, and public health specialists to determine which fire-related contaminants are of the highest concern in the ocean for safe recreation at beaches along the West Maui coastline.

The Lāhainā fire was unique given its proximity to the ocean, the age of the buildings that burned, and the number of structures that were destroyed. What we do know is that a large number of dangerous toxins were released during the fire. In addition to the contaminants that immediately leaked from the sunken boats, significant amounts of ash were deposited in coastal waters and continue to cover the burnt area of Lāhainā Town.

This ash can contain a variety of harmful toxins, including heavy metals, Polynuclear (Polycyclic) Aromatic Hydrocarbons (PAH’s), Volatile and Semivolatile Organic Compounds (VOC & SVOC), Asbestos, Polychlorinated Biphenyls (PCB’s), Dioxins and Furans, and Per- and Polyfluoroalkyl Substances (PFAS), as well as Nitrates and Phosphates. 

Front street sampling

In November DOH released preliminary results from samples they took of the toxic ash in Lāhainā. The County found elevated levels of metals as well as the presence of PAH’s. 

The two main strategies that are being used to contain and minimize the spread of toxic ash are the application of Soiltac® (a soil stabilizer) on the footprint of burned buildings and setting up roughly 4 miles of envirosock stormwater filters, as well as fences and curtains to prevent debris from flowing into the ocean and local waterways. The big concern, though, is that many of the contaminants in the ash are water soluble - meaning that they can flow freely through the socks and current management measures.

As such, our focus has been on identifying the most hazardous water soluble contaminants that would likely make their way to the ocean and put human health at risk. We also had to consider the feasibility of sampling and analysis. All samples had to be shipped off-island, and certain contaminants have very short hold times and specific sampling and holding protocols. 

enviro-sock lining Pāpalaua St.
Enviro-socks lining Front Street are designed to stop the flow of debris into the ocean.
Enviro-socks with perforations lining storm drain on Front St.
Enviro-socks lining stream from Mokuhinia going to 505 Front St.

Storm drain at Shark Pit


What Are We Testing For?

On the early morning of January 10, 2024, Surfrider Foundation staff members Lauren Blickley and Hanna Lilley suited up in waders, N95 masks, gloves and assembled sample bottles at Hanakaʻōʻō beach park. The previous night's heavy rains (nearly 4 inches of precipitation in Lāhainā) left a large plume of brown water stretching the coast of Maui’s West side. This was a day we have all feared, yet knew was coming. 

Surfrider Foundation Maui Fire Response Coordinator, Hanna Lilley, collecting water quality samples from the "Shark Pit" area of Lāhainā. 
Māla Ramp

Processing samples at Māla Ramp

 Lāhainā Harbor
Olowalu surf spot 


We sampled eight sites, one North and one South of the burn area (Hanakaʻōʻō and Olowalu) and six within the burn area. We shipped our samples overnight to Physis Labs to run analysis for Heavy Metals and Polynuclear Aromatic Hydrocarbons. 

Hanakaʻōʻō beach park-1

Heavy Metals

Fires release heavy metals from various sources including building materials, electronics, and vehicles. Older buildings (older than 1978) are often more likely to have heavy metals in their construction materials including lead-based paint. 

Given the old age of the buildings in Lāhainā, as well as preliminary DOH data, we have a pretty good idea that there are significant levels of heavy metals already deposited in the ocean. Ingestion and inhalation of these metals pose significant human health risks ranging from nausea and vomiting, ulcers, developmental problems, to circulatory, respiratory, and neurological issues, as well as cancer. 

Another issue with heavy metals is that they are in their base elemental form, meaning they cannot be broken down to non-toxic forms, only sequestered. With all of the other contaminants, there is an ability to use bioremediation measures to break down the contaminants to less harmful compounds. This means heavy metal pollution will be a persistent issue in the coming years. 

Surfrider Foundation is sampling the water off Lāhainā for the following metals: 

Aluminum (Al) Mercury (Hg)
Antimony (Sb) Molybdenum (Mo)
Arsenic (As) Nickel (Ni)
Beryllium (Be) Selenium (Se)
Cadmium (Cd) Silver (Ag)
Chromium (Cr) Thallium (Tl)
Cobalt (Co) Tin (Sn)
Copper (Cu) Titanium (Ti)
Iron (Fe) Vanadium (V)
Lead (Pb) Zinc (Zn)
Manganese (Mn)  


Polynuclear Aromatic Hydrocarbons (PAHʻs)

PAH’s are well known carcinogens and chemically stable compounds that come from the incomplete burning of organic materials such as wood, plastics, tires, building materials. PAH’s are important to look at in ocean water as they are very mobile, even more so than metals, and don’t require high concentrations or long duration of exposure to become toxic to humans. 

PAH's that we are sampling for include the following:

1-Methylnaphthalene Benzo[b]fluoranthene
1-Methylphenanthrene Benzo[e]pyrene
2,3,5-Trimethylnaphthalene Benzo[g,h,i]perylene
2,6-Dimethylnaphthalene Benzo[k]fluoranthene
2-Methylnaphthalene Biphenyl
Acenaphthene Chrysene
Acenaphthylene Dibenz[a,h]anthracene
Anthracene Dibenzothiophene
Benz[a]anthracene Fluoranthene
Benzo[a]pyrene Fluorene


Why is Nearshore Water Sampling Important?

While it can be easy to place hope in the sheer volume of the ocean to dilute the toxic contaminants in ash below a level that would pose a health risk to ocean users, Surfrider would like to have scientific data to better inform how safe the water along the West Maui coastline is, or is not. People and recreation-based businesses have really been looking forward to getting back into the water, but there has been a real vacuum of water quality information and we are looking forward to helping to meet that need.

People often assume that if the water is clear then it must be safe.  While it is certainly true that runoff during Brown Water events brings pollution down to the beach, water clarity can not be relied on to determine if it is safe for human contact.  Many of the ash related contaminants will clump together with sediment and other organic material in the water and sink to the ocean floor.  Storms, wave action and other physical disturbances, however, can resuspend this material into both the water and air causing people to be exposed to illness-causing toxins through dermal exposure, ingestion and inhalation.


Water Quality Results

Water samples from the Lāhainā area were collected and shipped on Thursday, January 10, 2024. We expect to receive the results from the heavy metals and PAH sampling within the next 2-3 weeks. 

In addition to the heavy metals and PAH sampling, we sampled for enterococcus bacteria levels. Our results showed very high bacteria levels in the burn area at Māla Tavern, Māla Ramp, and Pāpalaua St. At each of these locations there was stream water flowing directly into the water, even carrying visible ash. We also had high enterococcus bacteria counts at Honolua bay and Guard Rails as well as on the South Side at Kihei Canoe club and the Cove.

At this time, we continue to suggest that the community avoid entering the ocean in and around the Lāhainā area - particularly when the water is brown or immediately after heavy rains. Additional water quality results will help better inform our ocean going community as to the human health impacts in this area.

To support the Surfrider Maui Chapterʻs ongoing water quality monitoring and other fire response efforts, please consider making a donation