Approximately 100 gallons of sewage spilled into Stenner Creek in downtown San Luis Obispo early Tuesday morning.
A blocked sewer line near the CHP office at 675 California Boulevard caused sewage to overflow a manhole, according to the San Luis Obispo County Public Health Department.
The sewage then flowed to a storm drain, and eventually reached Stenner Creek, which connects with San Luis Creek and flows to Avila Beach.
Workers were able to place sandbags around the original spill and vacuumed sewage from the storm drains along Highway 101 and Olive Street.
Of the 1,000 gallons that spilled, an estimated 100 gallons of sewage made it into the creek.
Warning signs have been posted at Avila Beach, and samples of ocean water will be analyzed to determine the level of bacteria levels. The warning signs will remain posted until there is no health risk due to elevated bacteria levels.
The downtown portion of San Luis Creek was not affected by the spill, according to officials.