Maui water quality

We watch happily as our babies and toddlers splash, and our older kids swim, surf and paddle, in the ocean. 

But how clean is the ocean water along Maui’s coasts? It’s an important consideration for anyone who loves ocean recreation. Clean ocean water is also necessary for the survival of Maui’s coral reefs; a fragile ecosystem susceptible to even slight changes in ocean chemistry. Corals and their larvae can be damaged when sediment is in the water column or ocean temperatures rise and become too warm. 

Hui O Ka Wai Ola (Association Of The Living Waters) has been collecting important water quality data along Maui’s leeward coasts since 2016. This community-based program, co-managed by The Nature Conservancy, Maui Nui Marine Resource Council and West Maui Ridge to Reef Initiative, works with nearly 40 volunteers to regularly gather and generate quality-assured coastal water-quality data at 41 South and West Maui locations. They then provide this data to Hawaii’s Department of Health, resource agencies, non-governmental organizations and researchers. Importantly, the Hui’s open data is available to the public at their website

The Hui team regularly gathers data on turbidity, temperature, salinity, dissolved oxygen (DO), pH and dissolved nutrients (including nitrogen and phosphorus) at each site. The monitoring has revealed that elevated nutrients are common at South Maui sites (see graph above) especially at Cove Park and a few northwest Maui sites, indicating wastewater or fertilizer contamination. Water that looks murky (due to increased sediment) is more common in places like Ukumehame, Kahana, Kalepolepo and Kalama Park, among others. 

Recently, the Hui started sampling at their South Maui sites for Enterococcus, an indicator bacteria used by Hawaii’s Department of Health to determine areas possibly harmful to human and ecosystem health. The Hui is using this data to look for long term trends in areas with high bacteria levels, and to see what other parameters (such as turbidity) might correlate. Thankfully, many bacteria harmful to humans are intolerant to salt water. Researchers are working to better understand when a beach may not be healthy for people, so a warning can be given like the public advisory sent out on November 8 regarding Kanaha Beach. In the meantime, a good rule of thumb is to avoid entering the ocean when the water is brown since pathogens can be attached to the sediment.

To learn more, or to join as a volunteer, go to

Hui O Ka Wai Ola is supported by Maui County’s Mayor’s Office of Economic Development, Hawaii Tourism, Makana Aloha Foundation, Napili Bay and Beach Foundation, Honua Kai West Maui Community Fund, North-Beach West Maui Benefit Fund and others.

Image Credit: Hui O Ka Wai Ola

Issue 60 NavigationMaui Teachers Need To Be Paid More! >>Giving the Gift of Life to Another Family >>


Please enter your comment!
Please enter your name here