A wastewater overflow of about 2,500 gallons yesterday on Lana'i was caused by grease accumulation in the mainline on Fraser Avenue, according to Maui County Department of Environmental Management officials.

The wastewater flowed from a sewer manhole on Fraser Avenue, down the street, into neighborhood yards and a storm drain that does not connect to the ocean. The incident was reported at 3:20 p.m.

The line was unblocked, the spill sites disinfected and state Department of Health notified, officials said.