Clean ocean water is essential for healthy coral reefs. It’s also important to visitors and residents who enjoy swimming, snorkeling, diving, paddling, fishing and surfing along Maui’s coasts.
Maui Nui Marine Resource Council is proud to be a major partner in an innovative community-based water quality monitoring program called Hui O Ka Wai Ola (Association of Living Waters).
Filling an important need
Hawaiiʻs Department of Health (DOH) has a dedicated employee who routinely tests ocean water quality at 81 sites on Maui. Since 2015, this testing has only been for enterococcus bacteria, the EPA-approved indicator of bacteria that can cause human illness.
We add to the data collected by the Department of Health with our testing that keeps a close eye on changing water quality conditions that can harm our coral reefs.
Hui O Ka Wai Ola is a community-based program that works with more than 50 volunteers, to regularly gather additional data about sediment, nutrients in the water, temperature, pH and more at 48 locations along Mauiʻs south and west shores. We believe this data will allow for more effective management of our nearshore waters and ultimately, healthier coral reefs.
What We Test For
How it is measured: We gather samples at knee depth, then use a turbidity meter onsite to measure the amount of sediment (turbidity) in the water.
How changes are caused: Sediment carried from the land to the ocean (by streams, flooding, storm runoff) can cause ocean water to become brown or murky.
Why it is a concern: Sediment blocks sunlight from reaching reefs and can smother corals.
What we can do: When we find areas with high levels of turbidity, we can address upslope issues such as grading or clearing of land that caused sediment to flow into the ocean.
How it is measured: We measure pH, salinity and water temperature onsite using portable, handheld equipment.
How changes are caused: Changes in ocean chemistry can be caused by climate change and other local factors. Salinity can be changed by freshwater flowing into the ocean. Water temperature can fluctuate by season and can also be caused by climate change. Ocean acidity can be increased warming ocean temperatures. Warmer water also holds less dissolved oxygen (needed for aquatic plants and animals to survive).
Why it is a concern: Corals are very sensitive to changes in ocean chemistry, including increased ocean water acidity. Corals bleach when water temperature increases; collecting water temperature can help track localized variations between sites.
What we can do: We can monitor changes in reef health against changes in ocean water quality and continue to advocate for ways to reduce greenhouse gases and reverse climate change.
Nutrients (nitrogen and phosphorous)
How they are measured: Water samples are gathered, refrigerated and shipped on ice to the SOEST Analytical Laboratory on Oahu for analysis of nitrogen and phosphorous.
How changes are caused: High levels of nitrogen and phosphorous can indicate pollution from wastewater, run-off from agriculture, landscaping and/or golf courses. T
Why itʻs a concern: Too much nitrogen can cause an increase in invasive algae (limu), which is damaging to coral reefs.
What we can do: When we identify ocean areas with high levels of nutrients, we can pinpoint and address up-slope areas that are sources.
How it is measured: Water samples are gathered in sterile bags, which are then sealed and refrigerated. Samples are shipped on ice to regional labs, where they are analyzed for Enterococcus bacteria.
How it is caused: Bacteria may result from wastewater pollution. Enterococcus bacteria also live in soil and can be carried into the ocean via runoff.
Why itʻs a concern: Enterococcus bacteria are generally not harmful by themselves but do indicate the possible presence of pathogenic (disease-causing) bacteria, viruses, and protozoans that also live in human and animal digestive systems.
Where We Test
Mile Marker 14
Peter Martin Hale
Olowalu Shore Front
505 Front Street
DT Beach (Fleming N)
Kapalua Bay (Fleming S)
Kihei Canoe Club
Mai Poina ‘Oe Ia’u
Kihei South (Lipoa)
Poolenalena (Chang’s Beach)
South Maluaka Beach
Oneuli (black sand beach)
Makena Beach Shoreline
Ahihi Kinau North
Ahihi Kinau South
Hui O Ka Wai Ola works closely with the State of Hawaii Department of Health (DOH). The program is managed by these nonprofit partners:
- Maui Nui Marine Resource Council (MNMRC)
- The Nature Conservancy (TNC)
- West Maui Ridge to Reef (R2R) Initiative