Hui O Ka Wai Ola Reports on Six Years of Monitoring Maui’s Coastal Water Quality 2016-2022

KIHEI, HI – How do you know the water off your favorite beach is clean enough to swim in? You have a group of volunteers to thank for that.  Prompted by caring for the health of our residents, visitors, and the culturally important and ecologically sensitive coral reefs off our shores,  Hui O Ka Wai Ola (the Hui) has been keeping track of changes in water quality on Maui since 2016. (

Their data supports the efforts of the Department of Health to maintain a long-term record of nearshore water quality to inform efforts by state agencies and local nonprofit groups, like MNMRC, to reduce pollution impacts around the island. 


Water testing by HOKWO

The program, which follows strict quality control standards, measures physical qualities like water clarity, salinity, and temperature, as well as nutrient levels (which harm coral reefs if out of balance). A new collaborative project with the National Oceanographic and Atmospheric Administration (NOAA) is addressing a long-standing to-do from the Hawaii Coral Reef Initiative – evaluating pesticide contamination in the waters along our coast.

In he January 2023 MNMRC Know Your Ocean Speaker Series talk, Liz Yannell, the Hui’s Senior Team Lead, spoke about water quality observations taken over the last year and presented long-term trends from the past six years.  She also spoke about an ongoing collaborative project with the National Oceanographic and Atmospheric Administration (NOAA) to evaluate pesticide contamination in waters along our coast. View the talk here:

The Hui O Ka Wai Ola is a volunteer-based water quality monitoring organization that is a partnership between MNMRC, The Nature Conservancy, and the West Maui Ridge to Reef Initiative. The Hui’s members include volunteers from diverse backgrounds like scientists and community organizations. The Hawaii Department of Health is mandated to monitor coastal water quality around the islands and encourages partnerships with groups such as the Hui to improve data about pollutants threatening coral reefs and human health.

The Hui’s culture of collaboration and a deep interest in ocean health made for a natural partnership with  NOAA’s NCCOS (National Centers for Coastal Ocean Science) carrying out the fieldwork needed for a research study to address a long-standing gap in our understanding of Maui’s water quality, “current use” pesticides. Current use pesticides are still legally in use for pest control vs those, like DDT, that are no longer on the market in the US. Current use pesticides are one class of chemicals that has long been overlooked here in Maui.  Pollutants in the water are typically measured by collecting a one-time “grab sample” (i.e. a bottle of water). While these can provide good information, especially when repeated over time, the drawback to using grab samples is that low-level pollutants can be missed.  Passive samplers that absorb chemicals in the environment over time can be used to sample for a longer period of time. This minimizes the likelihood of missing the presence of a pollutant.  In the current project, silicone bands will be used to soak up any pesticides in the water at eighteen nearshore reefs along Leeward Maui. This work will provide a more comprehensive assessment of pesticide pollution in our coastal waters, and help guide pollution reduction actions if needed.

To view this talk, please visit

About Liz Yannell, Hui O Ka Wai Ola Senior Team Lead: 

Liz joined the Hui as Senior Team Leader in May 2022. She has a bachelor’s degree in environmental studies from Florida Gulf Coast University. In 2022, Liz graduated from the Marine Options Program at UH Maui and worked as an assistant in the marine lab on campus. She also often volunteered in the lab with Surfrider’s Blue Water Task Force.

Water quality monitoring with the HOKWO mobile water quality lab.

Hui O Ka Wai Ola volunteers and staff (left to right: Ylenia St. Louis, Kristina McHugh, Dan Crevier, and Liz Yannell) go beyond their regular ocean water testing duties in support of NOAA’s current-use pesticide study. Their data will help the science team understand ocean conditions where the pesticide sampling bands are deployed. Photo Credit: Tova Callender Location: North Kihei


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