King County is investigating an equipment malfunction that led to a wastewater spill in Lake Sammamish on March 24.

The Heathfield pump station, located at 3801 W. Lake Sammamish Parkway SE, had an equipment malfunction at about 4 a.m. on Sunday. A King County wastewater operator responded to the malfunctioning satation and stopped the overflow at 4:23 a.m. by keeping the watsewtaer in the sewer system and stopping the flow compeltely.

Contractors have cleaned up the site, and the county is now taking water samples every day to monitor water quality in Lake Sammamish.

The unstaffed Heathfield pump station moves wastewater to the South Treatment Plant in Renton.

After reporting the wastewater overflow to the regulatory authorities, King County posted signs to warn citizens not to use the water over the next several days to protect public health.

It is the second wastewater pump overflow in Bellevue this year. The first spill was on Feb. 12 due to a power outage causing a malfunction at the Sweyolocken pump station.