Kalapaki Beach in Lihue will be closed indefinitely until state health officials receive results of water-quality tests following a sewage spill Wednesday, Kauai County said Friday.

Signs notifying people of the closure will remain posted along the beach until the water is deemed safe by health officials. The public is advised to stay out of the water until the signs are removed.

An electrical malfunction in the plant about 5 p.m. Wednesday caused 400,000 to 500,000 gallons of secondary-treated wastewater to spill into a storm drain that leads to Kalapaki Bay, officials said.

Officials will be limiting the production of R-1 quality irrigation water from the sewage plant for the Kauai Lagoons golf courses until a new alarm system that monitors power interruptions is installed.

The water-quality tests are being conducted at a lab on O’ahu and are expected to be completed sometime this weekend.