Pink water at Keālia Pond on Maui likely due to halobacteria growth from high salinity

For the past nine days, staff at the Keālia Pond National Wildlife Refuge have been monitoring the color of the water at the pond, which has appeared bright pink in some photographs.

Preliminary analysis suggests that the color change appears to be the result of a single-celled organism called halobacteria. Officials with the US Fish and Wildlife Service say halobacteria are “salt-loving organisms” found in high salinity water bodies.

According to refuge staff, the salinity of water in the Keālia Pond outlet is currently greater than 70 parts per thousand, or twice the salinity of seawater.

Staff tell Maui Now that this high salinity is providing favorable conditions for the halobacteria, and is producing the pink color.

Water samples were sent to the University of Hawaiʻi for analysis, according to the US Fish and Wildlife Service. The preliminary analysis suggests that “it is not likely a toxic algae, for example the type that produces red tides.”

Refuge staff have been working with the Hawaiʻi State Department of Aquatic Resources and Department of Health to identify what is causing it and to determine a course of action.    

Additional analyses are being done by UH to determine the exact strain of the halobacteria.

As a precautionary measure, recommendations to the public include:

• Keep a safe distance and do not enter the water.
• Don’t consume any fish from the water.
• Ensure that pets don’t drink the water. 

The US Fish and Wildlife Service reports that they will continue to gather information and keep the public informed.