An estimated 200,000 gallons of partially treated wastewater overflowed at the Lahaina Wastewater Reclamation Facility during kona storm conditions on Saturday, according to the Maui County Department of Environmental Management.

The overflow occurred when heavy rainfall caused a manhole to become surcharged from excessive stormwater entering the sewer system. The incident began around 2 p.m. and stopped by 11 p.m.

Officials said the discharge — primarily filter backwash water and not fully disinfected treated wastewater — entered a storm drain system already experiencing significant flow and likely reached the ocean.

Warning signs have been posted in the area, and the state Department of Health has been notified.