Maui Coastal Water Quality Monitoring

Maui Coastal Water Quality Monitoring

Voyager’s “water quality” category now includes an overlay of coastal water quality measurements sampled by a network of citizen science volunteers on the island of Maui in the State of Hawaiʻi. Measurements of bacteria levels (Enterococcus) are used to assess water quality. These and other water measurements (water temperature, salinity, turbidity (water clarity), and pH) are collected periodically at several coastal locations across the island. With data spanning from 2010 to the present, sample sites include 10 locations along the west and south coasts of Maui: D.T. Fleming Beach Park, Haycraft Park, Kīhei Pier, Kōʻieʻie Fishpond, Kalama Beach Park, four sites at Lāʻie Wetlands, and Waiala Cove of ʻĀhihi-Kīnaʻu Natural Area Reserve. Additional sites may be added over time.

This community-based monitoring effort provides valuable data for resource management purposes, supplementing the State of Hawaiʻi’s existing monitoring efforts on Maui. Informed volunteer networks can serve as a community’s “eyes and ears” and will often provide the first indications of changes to a system. In addition to the value of early detection, it is important to maintain ongoing monitoring efforts to compile data and document resource conditions.

Voyager screenshot of Enterococcus concentrations across the island of Maui in the past 3 months (click here for larger image):

Voyager Screenshot

Enterococcus is an indicator bacteria that has been correlated with the presence of human pathogens (disease-causing organisms) and therefore with human illnesses such as gastroenteritis, diarrhea, and various infections in epidemiological studies. As such, it is commonly measured in coastal water quality monitoring programs. For reference, the U.S. Environmental Protection Agency (EPA) 1986 Ambient Water Quality Criteria for Bacteria (which the State’s Clean Water Branch uses) recommends that a water quality alert is posted if either: (a.) the latest water sample exceeds 104 CFU/100 mL of Enterococcus, or (b.) the geometric mean of the past 30 days of water samples exceeds 35 CFU/100 mL. One of the limitations of all available and EPA-approved test methods is that the sample must be incubated for about 24 hours.

Enterococcus at Haycraft Beach Park: (a.) time series plot since 2012; (b.) “more info” screen provides various plotting and download options:

a.)Voyager Screenshot   b.)Voyager Screenshot

Data are managed through an online repository, the Coral Reef Monitoring Data Portal (, developed and coordinated by the Coral Reef Alliance (CORAL) and its partners with funding provided by the Hawaiʻi Tourism Authority (HTA) and the National Oceanic and Atmospheric Administration (NOAA). Data collection is coordinated by the Hawaiʻi Division of Aquatic Resources (DAR), the Hawaiian Islands Humpback Whale National Marine Sanctuary (HIHWNMS), Aquanimity Now, the Digital Bus, Save Honolua Coalition, Project S.E.A.-Link, and other local organizations and agencies.

Data are publicly distributed by the Pacific Islands Ocean Observing System (PacIOOS). In addition to PacIOOS Voyager, data access is also enabled through our ERDDAP data server, which provides flexible data queries and a large variety of download formats. Formal metadata are available here.

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PacIOOS is the first regional association that was certified as a Regional Information Coordination Entity (RICE) by the U.S. Integrated Ocean Observing System (IOOS). Certification provides NOAA and its interagency partners a means to verify that a regional association’s organizational and operational practices, including data management, meet recognized and established standards set by NOAA.