The Navy’s sewage treatment plant at Pearl Harbor released 1.89 million gallons of partially treated wastewater offshore Monday amid heavy rains, according to Joint Base Pearl Harbor-Hickam officials.

The water was only partially treated because the rains damaged a transformer powering the plant’s ultraviolet treatment system, according to a base statement released Tuesday. The transformer was knocked out around 3 p.m. Monday, and the system came back online some five hours later.

The plant does have a backup generator but there was no pathway to connect the plant’s UV system to that power after the transformer was damaged, according to Charles Anthony, the base’s director of public affairs.

The wastewater entered the ocean at the plant’s regular release point about 1.5 miles offshore from Pearl Harbor. The state Department of Health asked the Navy to post warning signs along the shore, according to the base statement. 

The UV system is the fourth and final stage to disinfect the water, the Navy added.

In recent years, the Navy has run into numerous problems with government regulators for violations at the plant that have tainted the nearby coastal waters with sewage. 

In 2022, the health department ordered the Navy to pay nearly $9 million after it found hundreds of clean-water violations at the plant. Among the issues, the state found that six of the eight UV facilities at the plant weren’t operating.

One year earlier, the Navy entered a “facilities compliance agreement” with the Environmental Protection Agency to improve conditions at the treatment plant after it found “excessive toxic pollution” had occurred there. Among the steps to fix things, the Navy had to “develop a plan to prevent and respond to potential infrastructure failures at the plant.“ 

Anthony on Tuesday said that the Navy has since addressed both the state and federal requirements to fix the plant, and that $75 million of “significant upgrades” started construction at the facility in the past year.

Meanwhile, a brown water advisory from the health department remained in effect Tuesday for all of Oahu, meaning the public should stay out of the island’s beaches and streams due to the heavy storm runoff.

Civil Beat’s community health coverage is supported by the Swayne Family Fund of Hawaii Community Foundation, the Cooke Foundation, Atherton Family Foundation and Papa Ola Lokahi.